Channel state information and adaptive modulation and coding design for long-term evolution machine type communications

CROSS-REFERENCE TO RELATED APPLICATION(S)

0001This application claims the benefit of U.S. Provisional Application Ser. No. 61/753,395, entitled “CHANNEL STATE INFORMATION AND ADAPTIVE MODULATION AND CODING DESIGN FOR LONG-TERM EVOLUTION MACHINE TYPE COMMUNICATIONS” and filed on Jan. 16, 2013, which is expressly incorporated by reference herein in its entirety.

BACKGROUND

Field

0002The present disclosure relates generally to communication systems, and more particularly, to channel state information (CSI) and adaptive modulation and coding (AMC) design for long-term evolution (LTE) machine type communications (MTC).

Background

0003Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

0004These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long LTE. LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

0005In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus is an MTC UE. The UE determines a first modulation and coding scheme (MCS) that corresponds to an estimated channel between a base station and the UE. The UE receives data modulated and coded with a second MCS from the base station. The UE determines whether the second MCS differs from the first MCS by more than a threshold. The UE sends CSI after determining that the second MCS differs from the first MCS by more than the threshold.

0006In another aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus is an MTC UE. The UE receives a transmission time interval (TTI) bundling transmission from a base station. The UE decodes a subset of the TTI bundling transmission. The UE sends an acknowledgment to the base station to terminate the TTI bundling transmission early upon decoding the subset of the TTI bundling transmission. CSI is indicated to the base station through a percentage of the TTI bundling transmission received by the UE.

0007In another aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus sends an uplink transmission to a base station. The apparatus receives a data transmission from the base station, the data transmission having at least one of a MCS determined based on the uplink transmission or a TTI bundling size determined based on the uplink transmission.

0008In another aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus is an MTC UE. The UE determines CSI. The UE determines whether to send the CSI based on at least one of a timer or a threshold. The UE sends the CSI upon determining to send the CSI.

BRIEF DESCRIPTION OF THE DRAWINGS

0009<figref idref="DRAWINGS">FIG. 1</figref> is a diagram illustrating an example of a network architecture.

0010<figref idref="DRAWINGS">FIG. 2</figref> is a diagram illustrating an example of an access network.

0011<figref idref="DRAWINGS">FIG. 3</figref> is a diagram illustrating an example of a DL frame structure in LTE.

0012<figref idref="DRAWINGS">FIG. 4</figref> is a diagram illustrating an example of an UL frame structure in LTE.

0013<figref idref="DRAWINGS">FIG. 5</figref> is a diagram illustrating an example of a radio protocol architecture for the user and control planes.

0014<figref idref="DRAWINGS">FIG. 6</figref> is a diagram illustrating an example of an evolved Node B and user equipment in an access network.

0015<figref idref="DRAWINGS">FIG. 7A</figref> is a diagram illustrating an example of an evolved Multimedia Broadcast Multicast Service channel configuration in a Multicast Broadcast Single Frequency Network.

0016<figref idref="DRAWINGS">FIG. 7B</figref> is a diagram illustrating a format of a Multicast Channel Scheduling Information Media Access Control control element.

0017<figref idref="DRAWINGS">FIG. 8A</figref> is a diagram for illustrating a first exemplary method.

0018<figref idref="DRAWINGS">FIG. 8B</figref> is a diagram for illustrating a second exemplary method.

0019<figref idref="DRAWINGS">FIG. 8C</figref> is a diagram for illustrating a third exemplary method.

0020<figref idref="DRAWINGS">FIG. 8D</figref> is a diagram for illustrating a fourth exemplary method.

0021<figref idref="DRAWINGS">FIG. 9</figref> is a flow chart of a first method of wireless communication.

0022<figref idref="DRAWINGS">FIG. 10</figref> is a flow chart of a second method of wireless communication.

0023<figref idref="DRAWINGS">FIG. 11</figref> is a flow chart of a third method of wireless communication.

0024<figref idref="DRAWINGS">FIG. 12</figref> is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

0025<figref idref="DRAWINGS">FIG. 13</figref> is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

0026<figref idref="DRAWINGS">FIG. 14</figref> is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

0027<figref idref="DRAWINGS">FIG. 15</figref> is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

0028<figref idref="DRAWINGS">FIG. 16</figref> is a flow chart of a fourth method of wireless communication.

0029<figref idref="DRAWINGS">FIG. 17</figref> is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

0030<figref idref="DRAWINGS">FIG. 18</figref> is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

0031The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

0032Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

0033By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

0034Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and floppy disk where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

0035<figref idref="DRAWINGS">FIG. 1</figref> is a diagram illustrating an LTE network architecture. The LTE network architecture may be referred to as an Evolved Packet System (EPS) <b>100</b>. The EPS <b>100</b> may include one or more user equipment (UE) <b>102</b>, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) <b>104</b>, an Evolved Packet Core (EPC) <b>110</b>, a Home Subscriber Server (HSS) <b>120</b>, and an Operator's Internet Protocol (IP) Services <b>122</b>. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit-switched services.

0036The E-UTRAN includes the evolved Node B (eNB) <b>106</b> and other eNBs <b>108</b>. The eNB <b>106</b> provides user and control planes protocol terminations toward the UE <b>102</b>. The eNB <b>106</b> may be connected to the other eNBs <b>108</b> via a backhaul (e.g., an X2 interface). The eNB <b>106</b> may also be referred to as a base station, a Node B, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The eNB <b>106</b> provides an access point to the EPC <b>110</b> for a UE <b>102</b>. Examples of UEs <b>102</b> include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, or any other similar functioning device. The UE <b>102</b> may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

0037The eNB <b>106</b> is connected to the EPC <b>110</b>. The EPC <b>110</b> includes a Mobility Management Entity (MME) <b>112</b>, other MMEs <b>114</b>, a Serving Gateway <b>116</b>, a Multimedia Broadcast Multicast Service (MBMS) Gateway <b>124</b>, a Broadcast Multicast Service Center (BM-SC) <b>126</b>, and a Packet Data Network (PDN) Gateway <b>118</b>. The MME <b>112</b> is the control node that processes the signaling between the UE <b>102</b> and the EPC <b>110</b>. Generally, the MME <b>112</b> provides bearer and connection management. All user IP packets are transferred through the Serving Gateway <b>116</b>, which itself is connected to the PDN Gateway <b>118</b>. The PDN Gateway <b>118</b> provides UE IP address allocation as well as other functions. The PDN Gateway <b>118</b> is connected to the Operator's IP Services <b>122</b>. The Operator's IP Services <b>122</b> may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), and a PS Streaming Service (PSS). The BM-SC <b>126</b> may provide functions for MBMS user service provisioning and delivery. The BM-SC <b>126</b> may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a PLMN, and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway <b>124</b> may be used to distribute MBMS traffic to the eNBs (e.g., <b>106</b>, <b>108</b>) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

0038<figref idref="DRAWINGS">FIG. 2</figref> is a diagram illustrating an example of an access network <b>200</b> in an LTE network architecture. In this example, the access network <b>200</b> is divided into a number of cellular regions (cells) <b>202</b>. One or more lower power class eNBs <b>208</b> may have cellular regions <b>210</b> that overlap with one or more of the cells <b>202</b>. The lower power class eNB <b>208</b> may be a femto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The macro eNBs <b>204</b> are each assigned to a respective cell <b>202</b> and are configured to provide an access point to the EPC <b>110</b> for all the UEs <b>206</b> in the cells <b>202</b>. There is no centralized controller in this example of an access network <b>200</b>, but a centralized controller may be used in alternative configurations. The eNBs <b>204</b> are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway <b>116</b>.

0039The modulation and multiple access scheme employed by the access network <b>200</b> may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplex (FDD) and time division duplex (TDD). As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

0040The eNBs <b>204</b> may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the eNBs <b>204</b> to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data steams may be transmitted to a single UE <b>206</b> to increase the data rate or to multiple UEs <b>206</b> to increase the overall system capacity. This is achieved by spatially precoding each data stream (i.e., applying a scaling of an amplitude and a phase) and then transmitting each spatially precoded stream through multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UE(s) <b>206</b> with different spatial signatures, which enables each of the UE(s) <b>206</b> to recover the one or more data streams destined for that UE <b>206</b>. On the UL, each UE <b>206</b> transmits a spatially precoded data stream, which enables the eNB <b>204</b> to identify the source of each spatially precoded data stream.

0041Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

0042In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread-spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides “orthogonality” that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak-to-average power ratio (PAPR).

0043<figref idref="DRAWINGS">FIG. 3</figref> is a diagram <b>300</b> illustrating an example of a DL frame structure in LTE. A frame (10 ms) may be divided into 10 equally sized sub-frames. Each sub-frame may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block. The resource grid is divided into multiple resource elements. In LTE, a resource block contains 12 consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, 7 consecutive OFDM symbols in the time domain, or <b>84</b> resource elements. For an extended cyclic prefix, a resource block contains 6 consecutive OFDM symbols in the time domain and has 72 resource elements. Some of the resource elements, indicated as R <b>302</b>, <b>304</b>, include DL reference signals (DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) <b>302</b> and UE-specific RS (UE-RS) <b>304</b>. UE-RS <b>304</b> are transmitted only on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

0044<figref idref="DRAWINGS">FIG. 4</figref> is a diagram <b>400</b> illustrating an example of an UL frame structure in LTE. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

0045A UE may be assigned resource blocks <b>410</b><i>a</i>, <b>410</b><i>b </i>in the control section to transmit control information to an eNB. The UE may also be assigned resource blocks <b>420</b><i>a</i>, <b>420</b><i>b </i>in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

0046A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (RACH) (PRACH) <b>430</b>. The PRACH <b>430</b> carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (10 ms).

0047<figref idref="DRAWINGS">FIG. 5</figref> is a diagram <b>500</b> illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer <b>506</b>. Layer 2 (L2 layer) <b>508</b> is above the physical layer <b>506</b> and is responsible for the link between the UE and eNB over the physical layer <b>506</b>.

0048In the user plane, the L2 layer <b>508</b> includes a MAC sublayer <b>510</b>, a radio link control (RLC) sublayer <b>512</b>, and a packet data convergence protocol (PDCP) <b>514</b> sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer <b>508</b> including a network layer (e.g., IP layer) that is terminated at the PDN gateway <b>118</b> on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

0049The PDCP sublayer <b>514</b> provides multiplexing between different radio bearers and logical channels. The PDCP sublayer <b>514</b> also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer <b>512</b> provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARM). The MAC sublayer <b>510</b> provides multiplexing between logical and transport channels. The MAC sublayer <b>510</b> is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer <b>510</b> is also responsible for HARQ operations.

0050In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer <b>506</b> and the L2 layer <b>508</b> with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer <b>516</b> in Layer 3 (L3 layer). The RRC sublayer <b>516</b> is responsible for obtaining radio resources (e.g., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

0051<figref idref="DRAWINGS">FIG. 6</figref> is a block diagram of an eNB <b>610</b> in communication with a UE <b>650</b> in an access network. In the DL, upper layer packets from the core network are provided to a controller/processor <b>675</b>. The controller/processor <b>675</b> implements the functionality of the L2 layer. In the DL, the controller/processor <b>675</b> provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE <b>650</b> based on various priority metrics. The controller/processor <b>675</b> is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE <b>650</b>.

0052The transmit (TX) processor <b>616</b> implements various signal processing functions for the L1 layer (i.e., physical layer). The signal processing functions include coding and interleaving to facilitate forward error correction (FEC) at the UE <b>650</b> and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator <b>674</b> may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE <b>650</b>. Each spatial stream is then provided to a different antenna <b>620</b> via a separate transmitter <b>618</b>TX. Each transmitter <b>618</b>TX modulates an RF carrier with a respective spatial stream for transmission.

0053At the UE <b>650</b>, each receiver <b>654</b>RX receives a signal through its respective antenna <b>652</b>. Each receiver <b>654</b>RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor <b>656</b>. The RX processor <b>656</b> implements various signal processing functions of the L1 layer. The RX processor <b>656</b> performs spatial processing on the information to recover any spatial streams destined for the UE <b>650</b>. If multiple spatial streams are destined for the UE <b>650</b>, they may be combined by the RX processor <b>656</b> into a single OFDM symbol stream. The RX processor <b>656</b> then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB <b>610</b>. These soft decisions may be based on channel estimates computed by the channel estimator <b>658</b>. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB <b>610</b> on the physical channel. The data and control signals are then provided to the controller/processor <b>659</b>.

0054The controller/processor <b>659</b> implements the L2 layer. The controller/processor can be associated with a memory <b>660</b> that stores program codes and data. The memory <b>660</b> may be referred to as a computer-readable medium. In the UL, the controller/processor <b>659</b> provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink <b>662</b>, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink <b>662</b> for L3 processing. The controller/processor <b>659</b> is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

0055In the UL, a data source <b>667</b> is used to provide upper layer packets to the controller/processor <b>659</b>. The data source <b>667</b> represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the eNB <b>610</b>, the controller/processor <b>659</b> implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the eNB <b>610</b>. The controller/processor <b>659</b> is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB <b>610</b>.

0056Channel estimates derived by a channel estimator <b>658</b> from a reference signal or feedback transmitted by the eNB <b>610</b> may be used by the TX processor <b>668</b> to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor <b>668</b> are provided to different antenna <b>652</b> via separate transmitters <b>654</b>TX. Each transmitter <b>654</b>TX modulates an RF carrier with a respective spatial stream for transmission.

0057The UL transmission is processed at the eNB <b>610</b> in a manner similar to that described in connection with the receiver function at the UE <b>650</b>. Each receiver <b>618</b>RX receives a signal through its respective antenna <b>620</b>. Each receiver <b>618</b>RX recovers information modulated onto an RF carrier and provides the information to a RX processor <b>670</b>. The RX processor <b>670</b> may implement the L1 layer.

0058The controller/processor <b>675</b> implements the L2 layer. The controller/processor <b>675</b> can be associated with a memory <b>676</b> that stores program codes and data. The memory <b>676</b> may be referred to as a computer-readable medium. In the UL, the control/processor <b>675</b> provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE <b>650</b>. Upper layer packets from the controller/processor <b>675</b> may be provided to the core network. The controller/processor <b>675</b> is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

0059<figref idref="DRAWINGS">FIG. 7A</figref> is a diagram <b>750</b> illustrating an example of an evolved MBMS (eMBMS) channel configuration in an MBSFN. The eNBs <b>752</b> in cells <b>752</b>′ may form a first MBSFN area and the eNBs <b>754</b> in cells <b>754</b>′ may form a second MBSFN area. The eNBs <b>752</b>, <b>754</b> may each be associated with other MBSFN areas, for example, up to a total of eight MBSFN areas. A cell within an MBSFN area may be designated a reserved cell. Reserved cells do not provide multicast/broadcast content, but are time-synchronized to the cells <b>752</b>′, <b>754</b>′ and have restricted power on MBSFN resources in order to limit interference to the MBSFN areas. Each eNB in an MBSFN area synchronously transmits the same eMBMS control information and data. Each area may support broadcast, multicast, and unicast services. A unicast service is a service intended for a specific user, e.g., a voice call. A multicast service is a service that may be received by a group of users, e.g., a subscription video service. A broadcast service is a service that may be received by all users, e.g., a news broadcast. Referring to <figref idref="DRAWINGS">FIG. 7A</figref>, the first MBSFN area may support a first eMBMS broadcast service, such as by providing a particular news broadcast to UE <b>770</b>. The second MBSFN area may support a second eMBMS broadcast service, such as by providing a different news broadcast to UE <b>760</b>. Each MBSFN area supports a plurality of physical multicast channels (PMCH) (e.g., 15 PMCHs). Each PMCH corresponds to a multicast channel (MCH). Each MCH can multiplex a plurality (e.g., 29) of multicast logical channels. Each MBSFN area may have one multicast control channel (MCCH). As such, one MCH may multiplex one MCCH and a plurality of multicast traffic channels (MTCHs) and the remaining MCHs may multiplex a plurality of MTCHs.

0060A UE can camp on an LTE cell to discover the availability of eMBMS service access and a corresponding access stratum configuration. In a first step, the UE acquires a system information block (SIB) 13 (SIB13). In a second step, based on the SIB13, the UE acquires an MBSFN Area Configuration message on an MCCH. In a third step, based on the MBSFN Area Configuration message, the UE acquires an MCH scheduling information (MSI) MAC control element. The SIB <b>13</b> indicates (1) an MBSFN area identifier of each MBSFN area supported by the cell; (2) information for acquiring the MCCH such as an MCCH repetition period (e.g., 32, 64, . . . , 256 frames), an MCCH offset (e.g., 0, 1, . . . , 10 frames), an MCCH modification period (e.g., 512, 1024 frames), a signaling modulation and coding scheme (MCS), subframe allocation information indicating which subframes of the radio frame as indicated by repetition period and offset can transmit MCCH; and (3) an MCCH change notification configuration. There is one MBSFN Area Configuration message for each MBSFN area. The MBSFN Area Configuration message indicates (1) a temporary mobile group identity (TMGI) and an optional session identifier of each MTCH identified by a logical channel identifier within the PMCH, (2) allocated resources (i.e., radio frames and subframes) for transmitting each PMCH of the MBSFN area and the allocation period (e.g., 4, 8, . . . , 256 frames) of the allocated resources for all the PMCHs in the area, and (3) an MCH scheduling period (MSP) (e.g., 8, 16, 32, . . . , or 1024 radio frames) over which the MSI MAC control element is transmitted.

0061<figref idref="DRAWINGS">FIG. 7B</figref> is a diagram <b>790</b> illustrating the format of an MSI MAC control element. The MSI MAC control element may be sent once each MSP. The MSI MAC control element may be sent in the first subframe of each scheduling period of the PMCH. The MSI MAC control element can indicate the stop frame and subframe of each MTCH within the PMCH. There is one MSI per PMCH per MBSFN area.

0062In LTE, there has been interest in improvement of spectral efficiency, ubiquitous coverage, enhanced quality of service (QoS) support, etc., especially in high end devices such as smart phones, tablets, etc. There also has been interest in low-cost MTC UEs based on LTE, while considering factors such as reduction of maximum bandwidth, a single receive RF chain, reduction of peak rate, reduction of transmit power, and a half duplex operation. In LTE, an eNB performs AMC based on received CSI feedback. CSI feedback includes a channel quality indication (CQI), a rank indication (RI), and/or a precoding matrix index (PMI). The CSI feedback provides accurate information for a scheduler of the eNB for the purpose of the AMC. Having the CSI feedback is desirable because inefficiency in throughput and power consumption may result if there is no CSI feedback. For example, without the CSI feedback at a low SNR, using a high MCS will result in a high residual block error rate (BLER) even after a long TTI bundling. The high residual BLER can trigger higher layer retransmission. On the other hand, without the CSI feedback at a high SNR, using a low MCS will result in a much longer transmission. However, the conventional CSI feedback feature usually involves frequent CSI feedback, which can consume a large amount of power and UL resources. Moreover, the CSI feedback calculation involves extensive computation, which may increase a computational cost of MTC UEs. Therefore, there is a need for an efficient approach for providing CSI feedback. Methods for efficiently providing CSI feedback are provided infra with respect to <figref idref="DRAWINGS">FIGS. 8A</figref>, <b>8</b>B, <b>8</b>C, and <b>8</b>D. Each of the methods provided with respect to <figref idref="DRAWINGS">FIGS. 8A</figref>, <b>8</b>B, <b>8</b>C, and <b>8</b>D may be performed individually or together with one or more of the other methods.

0063<figref idref="DRAWINGS">FIG. 8A</figref> is a diagram <b>810</b> for illustrating a first exemplary method. During an initial connection set up (e.g., in a RACH procedure), an MTC UE <b>803</b>A may convey CSI to the eNB <b>805</b>A. The MTC UE <b>803</b>A receives reference (pilot) signals <b>811</b> from an eNB <b>805</b>A. Based on the reference signals, the MTC UE <b>803</b>A estimates a channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A. The MTC UE <b>803</b>A then determines <b>813</b> a first (expected) MCS that corresponds to the estimated channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A. The MTC UE <b>803</b>A may estimate the channel in each of multiple subframes. The MTC UE <b>803</b>A may average the channel estimate over the multiple subframes. After determining the first MCS, the MTC UE <b>803</b>A receives data <b>815</b> modulated and coded with a second (current) MCS from the eNB <b>805</b>A, and determines <b>817</b> whether the second MCS differs from the first MCS by more than a threshold. If the second (current) MCS differs from the first (expected) MCS by more than a threshold T, then the second MCS significantly deviates from the true channel statistics. If the MTC UE <b>803</b>A determines that the second MCS significantly deviates from the true channel statistics, the MTC UE <b>803</b>A sends CSI <b>819</b> to the eNB <b>805</b>A. According to the first exemplary method, the MTC UE <b>803</b>A provides CSI feedback only when the CSI feedback is needed (e.g., after the second MCS differs from the first MCS by more than the threshold). Providing CSI feedback only when needed saves power and UL resources.

0064The threshold T may be an integer greater than or equal to zero that corresponds to a number of bits per symbol that the MCS provides. For example, assume the current MCS is 16-QAM and the expected MCS is QPSK. 16-QAM provides 4 bits/symbol, whereas QPSK provides 2 bits/symbol. The difference between 16-QAM and QPSK may be equal to 2. If the threshold Tis set to 0 or 1, then the MTC UE <b>803</b>A will determine that the current MCS significantly deviates from the expected MCS. However, if the threshold T is set to 2, then because the difference between 16-QAM and QPSK is not greater than T, the MTC UE <b>803</b>A will determine that the current MCS does not significantly deviate from the expected MCS. If the threshold T is set to 2 and the expected MCS is QPSK, the MTC UE <b>803</b>A will only determine that the current MCS significantly deviates from the true channel statistics when the current MCS is 64-QAM or higher, corresponding to 5 or more bits/symbol. The threshold T may be determined in other ways, such as for example, corresponding to an MCS index. For example, assume the current MCS is MCS 4 (the MCS index is 4) and the expected MCS is MCS 2 (the MCS index is 2). The difference between MCS 2 and MCS 4 may be equal to 2. If the threshold T is set to 0 or 1, then the MTC UE <b>803</b>A will determine that the current MCS significantly deviates from the expected MCS. However, if the threshold T is set to 2, then because the difference between MCS 2 and MCS 4 is not greater than T, the MTC UE <b>803</b>A will determine that the current MCS does not significantly deviate from the expected MCS. If the threshold Tis set to 2 and the expected MCS is MCS 2, the MTC UE <b>803</b>A will only determine that the current MCS significantly deviates from the true channel statistics when the current MCS is MCS 5 or higher.

0065The eNB <b>805</b>A may determine an initial AMC based on a lowest MCS (e.g., BPSK) or based on CSI feedback from the MTC UE <b>803</b>A (e.g., CSI feedback provided during an initial connection setup, such as during a RACH procedure). The eNB <b>805</b>A may continue to use the same MCS for DL transmissions unless the MTC UE <b>803</b>A provides updated CSI feedback. If the MTC UE <b>803</b>A provides updated CSI feedback, the eNB <b>805</b>A may determine the AMC based on the received CSI feedback and continue to use the determined AMC until additional CSI feedback is received.

0066As discussed supra, the MTC UE <b>803</b>A may perform long-term averaging of the channel, but send the CSI to the eNB <b>805</b>A only if the current MCS significantly deviates (better or worse) from its true channel statistics. Accordingly, the MTC UE <b>803</b>A may average the channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A over multiple subframes, and send CSI feedback only if the expected MCS corresponding to the estimated channel and the current MCS differ by a threshold. Thus, the CSI feedback is event driven. For example, if the MTC UE <b>803</b>A determines an expected MCS of QPSK, but receives a data transmission with 64-QAM (which is significantly better than QPSK), the MTC UE <b>803</b>A may determine to send updated CSI feedback to the eNB <b>805</b>A. For another example, if the MTC UE <b>803</b>A determines that an expected MCS is 64-QAM, but receives a data transmission with QPSK (which is significantly worse than 64-QAM), the MTC UE <b>803</b>A may determine to send updated CSI feedback to the eNB <b>805</b>A.

0067Once the MTC UE <b>803</b>A determines to send CSI feedback to the eNB <b>805</b>A, the MTC UE <b>803</b>A may store the CSI feedback until the next UL transmission. In a first configuration, the MTC UE <b>803</b>A may include the CSI in a MAC header within a scheduled UL data (PUSCH) transmission sent to the eNB <b>805</b>A. In a second configuration, if there is no scheduled PUSCH transmission, but the MTC UE <b>803</b>A has a buffer status report (BSR) to transmit to the eNB <b>805</b>A (i.e., the MTC UE <b>803</b>A has data to transmit), the MTC UE <b>803</b>A may send the CSI in a MAC header with an UL PUSCH transmission including the BSR. The BSR indicates to the eNB <b>805</b>A an amount of data in the buffer of the MTC UE <b>803</b>A. If the MTCH UE <b>803</b>A has a BSR to send to the eNB <b>805</b>A, the MTC UE <b>803</b>A will send a scheduling request (SR) to the eNB <b>805</b>A requesting UL resources for sending the BSR. In the second configuration, the MTC UE <b>803</b>A sends the CSI and BSR in the resources allocated for the BSR.

0068In a third configuration, if the MTC UE <b>803</b>A has no scheduled UL transmission (e.g., PUSCH transmission) and has no BSR to transmit to the eNB <b>805</b>A, the MTC UE <b>803</b>A may send an SR or perform a random access channel (RACH) procedure in order to send updated CSI to the eNB <b>805</b>A. In the third configuration, the MTC UE <b>803</b>A may send a request to the eNB <b>805</b>A for sending the CSI upon determining that the second MCS differs from the first MCS by more than the threshold. The MTC UE <b>803</b>A may receive a response from the eNB <b>805</b>A based on the request and send the CSI based on the received response. In one configuration, the request may be an SR and the received response may be an UL grant. Thus, for example, when the current MCS differs from the expected MCS by more than the threshold, the MTC UE <b>803</b>A has no scheduled PUSCH transmission, and the MTC UE <b>803</b>A has no BSR to transmit to the eNB <b>805</b>A, an SR may be triggered to request the eNB <b>805</b>A to provide UL resources for sending the CSI. In another configuration, the request and response may be associated with a RACH procedure. Accordingly, the request may be a random access preamble and the response may be a random access response. Thus, for example, when the current MCS differs from the expected MCS by more than the threshold, the MTC UE <b>803</b>A has no scheduled PUSCH transmission, and the MTC UE <b>803</b>A has no BSR to transmit to the eNB <b>805</b>A, the MTC UE <b>803</b>A may perform a RACH procedure and send a random access preamble to the eNB <b>805</b>A. The MTC UE <b>803</b>A may then receive a random access response from the eNB <b>805</b>A. Based on the received random access response, the MTC UE <b>803</b>A may send the CSI to the eNB <b>805</b>A. In yet another configuration, the MTC UE <b>803</b>A may select a RACH format for a RACH procedure based on the CSI and indicate the CSI to the eNB <b>805</b>A through the selected RACH format in a RACH procedure. The MTC UE <b>803</b>A may indicate the CSI through a selected RACH format in the random access preamble and/or through a selected RACH format in the response to the random access response.

0069In a fourth configuration, the MTC UE <b>803</b>A may send the CSI to the eNB <b>805</b>A through an aperiodic CQI transmission. In the fourth configuration, the MTC UE <b>803</b>A receives an UL grant from the eNB <b>805</b>A, and the UL grant specifically indicates that CSI is to be sent in the allocated UL resources. The MTC UE <b>803</b>A transmits the CSI feedback in the allocated UL resources.

0070In a fifth configuration, if there is no UL transmission, the eNB <b>805</b>A may occasionally send an UL grant to the MTC UE <b>803</b>A for sending CSI feedback. Thus, when the MTC UE <b>803</b>A has not sent CSI for a time period greater than a threshold time period, the eNB <b>805</b>A may send an UL grant. The MTC UE <b>803</b>A may receive the UL grant from the eNB <b>805</b>A and send CSI to the eNB <b>805</b>A based on the received UL grant from the eNB <b>805</b>A. This procedure may be tied to a supervision procedure.

0071As discussed supra, the CSI reporting may be based on the MCS difference larger than a threshold. In addition, an alternative approach may be implemented to compare a currently measured path loss to a last reported path loss. If a difference between the currently measured path loss and the last reported path loss is significantly large (e.g., larger than a certain threshold), then the UE may send the CSI.

0072There are several approaches for reporting CSI feedback. In a first approach, the MTC UE <b>803</b>A may determine the CSI based on a lowest quality channel estimate over multiple subframes and report the CSI corresponding to the worst MCS (for power optimization). In a second approach, the MTC UE <b>803</b>A may determine the CSI based on an average of the estimated channels over multiple frames and report the average CSI (for spectral efficiency optimization). In a third approach, the MTC UE <b>803</b>A may determine both worst case and average CSI and report both the worse case and average CSI (for eNB scheduling flexibility). In a fourth approach, the MTC UE <b>803</b>A may determine the CSI based on one estimate of the channel among the estimated channels of the multiple subframes. In a fifth approach, the MTC UE <b>803</b>A may receive a configuration indicating how to determine the CSI, and then determine the CSI based on the received configuration. The configuration may indicate to the MTC UE <b>803</b>A to use one of the first through fourth approaches, or may indicate to the MTC UE <b>803</b>A to use a different approach for reporting CSI feedback.

0073If an MBSFN broadcast is used for data transmission, the MTC UE <b>803</b>A may receive information indicating MBSFN subframes, and determine the CSI based on the received information. Thus, the MTC UE <b>803</b>A may be notified of subframes that are transmitted using multicast/broadcast, and the MTC UE <b>803</b>A may treat the CSI feedback differently for those subframes. For example, if the MTC UE <b>803</b>A receives multicast/broadcast data, CSI feedback determined based on the received multicast/broadcast data may better than CSI feedback determined based on a received unicast data. Accordingly, the MTC UE <b>803</b>A may adjust or ignore channel estimates based on multicast/broadcast data.

0074If a decoupled DL and UL operation is used for the MTC UE <b>803</b>A, one cell in the eNB <b>805</b>A may be dedicated for DL while another cell in eNB <b>805</b>A may be dedicated for UL. In this case, the MTC UE <b>803</b>A may receive the data from a first cell of the eNB <b>805</b>A and send CSI to a second cell of the eNB <b>805</b>A, where the second cell is different from the first cell. The first cell of the eNB <b>805</b>A may be a DL serving cell, and the second cell of the eNB <b>805</b>A may be an UL serving cell.

0075As discussed supra, the MTC UE <b>803</b>A may select a RACH format for a RACH procedure based on the CSI. The MTC UE <b>803</b>A sends the CSI through the RACH procedure and indicates the CSI through the selected RACH format. In other words, the MTC UE <b>803</b>A may choose a RACH format (e.g., a different length of a RACH bundle) to indicate to the eNB <b>805</b>A its radio condition, such that the format of RACH indicates the CSI to the eNB <b>805</b>A. For example, if the channel is in a poor condition, the MTC UE <b>803</b>A may select a RACH with a longer transmission time. This RACH format of the longer transmission time indicates to the eNB <b>805</b>A that the channel is in a poor condition. On the other hand, for example, if the channel is in a good condition, the MTC UE <b>803</b>A may select a compact RACH channel, and this RACH format indicates to the eNB <b>805</b>A that the channel is in a good condition. Depending on the RACH format, the eNB <b>805</b>A may select an appropriate MCS and a bundling size for a subsequent DL transmission (e.g., msg2 with bundling). Similarly, the CSI information can be also sent in msg 3 or msg 5 during the RACH and RRC connection setup procedure.

0076For an initial RACH procedure, the MTC UE <b>803</b>A measures the DL path loss, and depending on the path loss, selects one of multiple RACH sequences/signatures (also referred to as format). If the MTC UE <b>803</b>A selects a normal RACH transmission, then subsequent transmissions by the MTC UE <b>803</b>A (msg3 and msg5) and the eNB <b>805</b>A (msg2 and msg4) do not use TTI bundling. If the MTC UE <b>803</b>A selects a bundled RACH transmission with long TTI, then subsequent transmissions by the MTC UE <b>803</b>A (msg3 and msg5) and the eNB <b>805</b>A (msg2 and msg4) use the lowest MCS (e.g., BPSK) with TTI bundling.

0077The CSI feedback may be combined with other reports. In one approach, the MTC UE <b>803</b>A may receive a periodic supervision message from the eNB <b>805</b>A, and send a response to the eNB <b>805</b>A based on the received periodic supervision message, where the CSI is sent with the response. A periodic supervision may be needed to determine whether the MTC UE <b>803</b>A is accessible or whether the MTC UE <b>803</b>A is out of coverage or out of service (e.g., due to a bad battery). Thus, by sending a periodic supervision message to the MTC UE <b>803</b>A and receiving a response from the MTC UE <b>803</b>A, the eNB <b>805</b>A can determine whether the MTC UE <b>803</b>A is alive. For example, eNB <b>805</b>A may send a periodic supervision message, and if the MTC UE <b>803</b>A sends back an acknowledgement in response to the request, the eNB <b>805</b>A may determine that the MTC UE <b>803</b>A is accessible. MTC UE <b>803</b>A may also send CSI feedback with the acknowledgement to the supervision request.

0078In another approach for combining the CSI with other reports, the MTC UE <b>803</b>A may determine a reference signal received quality (RSRQ) and/or a reference signal received power (RSRP), and send the RSRP and/or the RSRQ to the eNB <b>805</b>A, where the CSI is sent with the at least one of the RSRP or the RSRQ. Thus, according to this approach, the MTC UE <b>803</b>A may measure the RSRP and/or the RSRQ and then when the MTC UE <b>803</b>A reports the measured RSRP/RSRQ to the eNB <b>805</b>A, the MTC UE <b>803</b>A may combine the CSI report with RSRP/RSRQ reporting and send the combined report to the eNB <b>805</b>A. The RSRP/RSRQ reporting may be event-driven. Further, the long term CSI reporting may be combined with the RSRP/RSRQ reporting.

0079In one configuration, the MTC UE <b>803</b>A determines a first bundling size that corresponds to an estimated channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A, receives data with a second bundling size from the eNB <b>805</b>A, and determines whether the second bundling size differs from the first bundling size by more than a threshold. The MTC UE <b>803</b>A then sends CSI after determining that the second bundling size differs from the first bundling size by more than the threshold. The threshold T may correspond to a bundling size difference. Accordingly, when a difference between the first bundling size and the second bundling size is greater than the threshold T, the MTC UE <b>803</b>A may determine to send the CSI to the eNB <b>805</b>A.

0080In one configuration, the eNB <b>805</b>A schedules the MTC UE <b>803</b>A for an uplink transmission with a particular MCS. The eNB <b>805</b>A determines the UL channel between the MTC UE <b>803</b>A and the eNB <b>805</b>A. The UL channel may be based on reference signals received from the MTC UE <b>803</b>A and/or whether the eNB can decode a bundled TTI transmission early. The eNB <b>805</b>A may determine an expected MCS and/or TTI bundling size based on the determined uplink channel. If the current MCS and/or TTI bundling size being received from the MTC UE <b>803</b>A is significantly different from the expected values (e.g., based on a threshold T, which may be a function of at least one of a modulation order (e.g., QPSK), an MCS, or a TTI bundling size), the eNB <b>805</b>A may send to the MTC UE <b>803</b>A information in the MAC header of a DL transmission packet requesting the MTC UE <b>803</b>A to adjust the UL transmission MCS and/or TTI bundling size for subsequent transmissions.

0081<figref idref="DRAWINGS">FIG. 8B</figref> is a diagram <b>830</b> for illustrating a second exemplary method. In the second exemplary method, an eNB <b>805</b>B transmits a long TTI bundle and an MTC UE <b>803</b>B sends an acknowledgement to early terminate when the MTC UE <b>804</b> can decode a subset of the TTI bundle. The eNB <b>805</b>B adapts to the channel condition based on the early termination statistics (e.g., the percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B). Accordingly, in the second exemplary method, the MTC UE <b>803</b>B need not determine or send CSI. As shown in <figref idref="DRAWINGS">FIG. 8B</figref>, the MTC UE <b>803</b>B receives a TTI bundling transmission <b>831</b> from the eNB <b>805</b>B, and decodes <b>833</b> a subset of the TTI bundling transmission. When the MTC UE <b>803</b>B decodes the subset of the TTI bundling transmission, the MTC UE <b>803</b>B sends an acknowledgement <b>835</b> to the eNB <b>805</b>B to terminate the TTI bundling transmission early. The CSI is indicated to the eNB <b>805</b>B though a percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B. Thus, the eNB <b>805</b>B can determine the CSI based on the percentage of the TTI bundling transmission received by the UE, and adapt <b>837</b> to the channel condition of this CSI by selecting an MCS appropriate for determined CSI. For example, if the percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B is low, this indicates to the eNB <b>805</b>B that the MTC UE <b>803</b>B was able to decode the subset of the TTI bundling transmission early, and thus the channel is good. The eNB <b>805</b>B may also transmit data <b>839</b> modulated and coded with an MCS to the MTC UE <b>803</b>B, where the MCS is based on the percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B. A TTI bundling size of the data <b>839</b> may also be based on the percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B.

0082In a default behavior, the eNB <b>805</b>B may use a default bundling size and an MCS for DL transmissions and monitor acknowledgements from the MTC UE <b>803</b>B for possible early termination. For example, the eNB <b>805</b>B may initially use a default bundling size of 100 subframes (100 TTIs). If the MTC UE <b>803</b>B early terminates after 10 subframes and informs the eNB <b>805</b>B of the early termination, the eNB <b>805</b>B may determine that the MTC UE <b>803</b>B decoded the transmission after receiving just 10% of the transmission. The eNB <b>805</b>B may then increase the MCS for a subsequent TTI bundled data transmission, and send the TTI bundled data transmission over 10 TTIs.

0083In addition, for half duplex operations or TDD, the bundling operation can overwrite the DL and UL direction change. For example, if there is a DL of 10 milliseconds of the TTI bundle, then all 10 milliseconds of DL transmission may be completed without changing a direction to UL.

0084In one configuration, the eNB <b>805</b>B sends a first TTI bundling transmission to the MTC UE <b>803</b>B. The eNB <b>805</b>B receives an acknowledgment from the UE that the TTI bundling transmission was terminated early, and determines an MCS based on a percentage of the first TTI bundling transmission received by the MTC UE <b>803</b>B. The eNB <b>805</b>B sends a second TTI bundling transmission to the MTC UE <b>803</b>B modulated and coded with the MCS determined based on the percentage of the first TTI bundling transmission

0085<figref idref="DRAWINGS">FIG. 8C</figref> is a diagram <b>850</b> for illustrating a third exemplary method. In the third exemplary method, an MTC UE <b>803</b>C transmits a one-shot signal (e.g., a one-shot sounding reference signal (SRS)) to an eNB <b>805</b>C via an UL channel, and the eNB <b>805</b>C adjusts the MCS/bundling size depending on the UL path loss. Thus, in this embodiment, the MTC UE <b>803</b>C does not need to calculate the CSI and to provide the CSI to the eNB <b>805</b>C. As shown in <figref idref="DRAWINGS">FIG. 8C</figref>, the MTC UE <b>803</b>C sends an UL transmission <b>851</b> to the eNB <b>805</b>C. Based on the UL transmission, the eNB <b>805</b>C determines <b>853</b> an MCS and/or a TTI bundling size. The eNB <b>805</b>C then transmits data <b>855</b> to the MTC UE <b>803</b>C. This data transmission received by the MTC UE <b>803</b>C has an MCS and/or a TTI bundling size determined based on the UL transmission. Because the eNB <b>805</b>C is determining the MCS based on an UL channel estimation rather than a DL channel estimation, the third exemplary method may be used only for TDD (the UL channel estimation is based on the same subcarriers as a DL channel estimation).

0086In one configuration, the eNB <b>805</b>C receives an uplink transmission from the MTC UE <b>803</b>C, and determines an MCS based on the received uplink transmission and/or a TTI bundling size based on the received uplink transmission. The eNB <b>805</b>C sends a data transmission to the MTC UE <b>803</b>C with the determined MCS and/or the determined TTI bundling size.

0087<figref idref="DRAWINGS">FIG. 8D</figref> is a diagram <b>870</b> for illustrating a fourth exemplary method. During an initial connection set up (e.g., in a RACH procedure), an MTC UE <b>803</b>D may convey CSI to the eNB <b>805</b>D. The MTC UE <b>803</b>D receives reference signals <b>871</b> from an eNB <b>805</b>D. Based on the reference signals <b>871</b>, the MTC UE <b>803</b>D estimates a channel between the eNB <b>805</b>D and the MTC UE <b>803</b>D. The MTC UE <b>803</b>D then determines <b>873</b> CSI that corresponds to the estimated channel between the eNB <b>805</b>D and the MTC UE <b>803</b>D. The MTC UE <b>803</b>D may estimate the channel in each of multiple subframes. The MTC UE <b>803</b>D may average the channel estimate over the multiple subframes. After determining the CSI, the MTC UE <b>803</b>D determines <b>875</b> whether to send the CSI to the eNB <b>805</b>D based on a threshold T2 and/or a timer. For example, if the CSI differs from a reference CSI by more than the threshold T2 (D_CSI≧T2, where D_CSIis the difference between the reference CSI and the CSI), the MTC UE <b>803</b> may send the CSI to the eNB <b>805</b>D. In other words, if a difference between the CSI and the reference CSI is greater than the threshold T2, the MTC UE <b>803</b>D may determine to send the CSI to the eNB <b>805</b>D. In another example, the MTC UE <b>803</b>D may set a timer upon sending CSI. When the timer expires, the MTC UE <b>803</b>D may determine to send the CSI to the eNB <b>805</b>D. The MTC UE <b>803</b>D may utilize both the threshold T2 and the timer. In such a configuration, the MTC UE <b>803</b>D determines to send the CSI when the difference between the CSI and the reference CSI is greater than the threshold T2, and upon expiration of the timer, even if the difference between the CSI and the reference CSI is not greater than the threshold T2. If the MTC UE <b>803</b>D determines to send, the MTC UE <b>803</b> sends the CSI <b>877</b> to the eNB <b>805</b>D. The MTC UE <b>803</b>D may send the CSI <b>877</b> in a MAC header. According to the fourth exemplary method, the MTC UE <b>803</b>D may provide CSI feedback only when the CSI feedback is needed and/or upon expiration of a timer (e.g., when the CSI differs from the reference CSI by more than the threshold T2 and/or the timer expires). Providing CSI feedback only when needed or infrequently based on a timer saves power and UL resources.

0088The MTC UE <b>803</b>D's determination to send the CSI to the eNB <b>805</b>D based on the threshold T2 may depend on a difference between the CSI and the reference CSI. The CSI may include a CQI, an RI, a PMI, an MCS, and/or path loss. Thus, the CSI may correspond to a CQI index. For example, assume that the CSI corresponds to a CQI index of 4 and the reference CSI corresponds to a CQI index of 8. Then, the difference between the CSI with the CQI index of 4 and the reference CSI with the CQI index of 8 is 4. In a first scenario, if the threshold T2 is less than or equal to 3, the threshold T2 is less than the difference between the CSI with the CQI index of 4 and the reference CSI with the CQI index of 8. Therefore, the MTC UE <b>803</b>D determines that the difference between the CSI and the reference CSI is greater than the threshold T2, and thus the CSI significantly deviates from the reference CSI. As a result, in the first scenario, the MTC UE <b>803</b>D determines to send the CSI to the eNB <b>805</b>D. On the other hand, in a second scenario, if the threshold T2 is greater than or equal to 5, then the MTC UE <b>803</b>D determines that the CSI does not significantly deviate from the reference CSI because the difference between the CSI with the CQI index of 4 and the reference CSI with the CQI index of 8 is not greater than the threshold T2. Therefore, in the second scenario, the MTC UE <b>803</b>D determines not to send the CSI to the eNB <b>805</b>D.

0089In one example, reference CSI may be CSI that the UE <b>803</b>D has previously reported to the eNB <b>805</b>D prior to determining the CSI at <b>873</b>. For example, prior to determining the CSI at <b>873</b>, the MTC UE <b>803</b>D may determine CSI based on previously received reference signals received from the eNB <b>805</b>D and report the reference CSI to the eNB <b>805</b>D. Thus, when the previously reported CSI is used as the reference CSI, the reference CSI varies depending on the reference signals received from the eNB <b>805</b>D. In another example, the reference CSI may be a fixed CSI that includes a fixed value as the reference CSI. In another example, the reference CSI may be based on path loss (e.g., DL path loss). In an aspect, a difference between a current path loss and a reference path loss (e.g. path loss included in the reference CSI) may be included in the CSI as the path loss information.

0090In another example, the MTC UE <b>803</b>D may determine the reference CSI based on an MCS of a data transmission received from the eNB <b>805</b>D. The reference CSI may be determined based on a mapping between an MCS and a CSI. For example, reference CSI with a CQI index of 4 may correspond to QPSK with a code rate of 0.03, and reference CSI with a CQI index of 8 may correspond to 16QAM with a code rate of 0.48. Thus, if an MCS of a data transmission received from the eNB <b>805</b>D is 16QAM with a code rate of approximately 0.48, then the MTC UE <b>803</b>D determines that the reference CSI corresponds to the CQI index of 8.

0091As discussed supra, the MTC UE <b>803</b>D may perform long-term averaging of the channel, but send the CSI to the eNB <b>805</b>D only if the CSI significantly deviates from the reference CSI. Accordingly, the MTC UE <b>803</b>D may average the channel between the eNB <b>805</b>D and the MTC UE <b>803</b>D over multiple subframes, and send CSI feedback only if the reference CSI and the CSI differ by the threshold T2. Thus, the CSI feedback is event driven. In an example where the threshold T2 is set to 4 and reference CSI corresponds to a CQI index of 8, if the MTC UE <b>803</b>D determines the CSI with a CQI index of 15, the MTC UE <b>803</b>D may determine to send CSI feedback to the eNB <b>805</b>D because the CSI's CQI index is significantly better (i.e., CQI index 15—CQI index 8≧4) than the reference CSI's CQI index of 8. For another example, if the MTC UE <b>803</b>D determines the CSI with a CQI index of 3, the MTC UE <b>803</b>D may determine to send CSI feedback to the eNB <b>805</b>D because the CSI's CQI index is significantly worse (i.e., CQI index 8−CQI index 3≧4) than the reference CSI's CQI index of 8.

0092Once the MTC UE <b>803</b>D determines to send CSI feedback to the eNB <b>805</b>D, the MTC UE <b>803</b>D may store the CSI feedback until the next UL transmission. In a first configuration, the MTC UE <b>803</b>D may include the CSI in a MAC header within a scheduled UL data (PUSCH) transmission sent to the eNB <b>805</b>D. In a second configuration, if there is no scheduled PUSCH transmission, but the MTC UE <b>803</b>D has a BSR to transmit to the eNB <b>805</b>D (i.e., the MTC UE <b>803</b>D has data to transmit), the MTC UE <b>803</b>D may send the CSI in a MAC header with a UL PUSCH transmission including the BSR. The BSR indicates to the eNB <b>805</b>D an amount of data in the buffer of the MTC UE <b>803</b>D. If the MTCH UE <b>803</b>D has a BSR to send to the eNB <b>805</b>D, the MTC UE <b>803</b>D will send a SR to the eNB <b>805</b>D requesting UL resources for sending the BSR. In the second configuration, the MTC UE <b>803</b>D sends the CSI and BSR in the resources allocated for the BSR.

0093In a third configuration, if the MTC UE <b>803</b>D has no scheduled UL transmission (e.g., PUSCH transmission) and has no BSR to transmit to the eNB <b>805</b>D, the MTC UE <b>803</b>D may send an SR or perform a RACH procedure in order to send updated CSI to the eNB <b>805</b>D. In the third configuration, the MTC UE <b>803</b>D may send a request to the eNB <b>805</b>D for sending the CSI upon determining to send the CSI based on the timer and/or the threshold T2. The MTC UE <b>803</b>D may receive a response from the eNB <b>805</b>D based on the request and send the CSI based on the received response. The response may be a UL grant. Subsequently, the MTC UE <b>803</b>D may send the CSI in a scheduled PUSCH of the UL grant. The MTC UE <b>803</b>D may send the CSI in the MAC header of the scheduled PUSCH of the UL grant or in a payload portion of the scheduled PUSCH of the UL grant. In one aspect, the MTC UE <b>803</b>D may send the CSI in message 3 (msg3) or message 5 (msg5) of the RACH procedure. In one configuration, the request may be an SR and the received response may be a UL grant. Thus, for example, when the CSI differs from the reference CSI by more than the threshold T2 and/or the timer expires, the MTC UE <b>803</b>D has no scheduled PUSCH transmission, and the MTC UE <b>803</b>D has no BSR to transmit to the eNB <b>805</b>D, an SR may be triggered to request the eNB <b>805</b>D to provide UL resources for sending the CSI. In another configuration, the request and response may be associated with a RACH procedure. The response received at the MTC UE <b>803</b>D may be a UL grant. Accordingly, the request may be a random access preamble and the response may be a random access response. Thus, for example, when the CSI differs from the reference CSI by more than the threshold T2 and/or the timer expires, the MTC UE <b>803</b>D has no scheduled PUSCH transmission, and the MTC UE <b>803</b>D has no BSR to transmit to the eNB <b>805</b>D, the MTC UE <b>803</b>D may perform a RACH procedure and send a random access preamble to the eNB <b>805</b>D. The MTC UE <b>803</b>D may then receive a random access response from the eNB <b>805</b>D. Based on the received random access response, the MTC UE <b>803</b>D may send the CSI to the eNB <b>805</b>D. In yet another configuration, the MTC UE <b>803</b>D may select a RACH format for a RACH procedure based on the CSI and indicate the CSI to the eNB <b>805</b>D through the selected RACH format in a RACH procedure. The MTC UE <b>803</b>D may indicate the CSI through a selected RACH format in the random access preamble and/or through a selected RACH format in the response to the random access response.

0094In a fourth configuration, the MTC UE <b>803</b>D may send the CSI to the eNB <b>805</b>D through an aperiodic CQI transmission. In the fourth configuration, the MTC UE <b>803</b>D receives a UL grant from the eNB <b>805</b>D, and the UL grant specifically indicates that CSI is to be sent in the allocated UL resources. The MTC UE <b>803</b>D transmits the CSI feedback in the allocated UL resources.

0095In a fifth configuration, if there is no UL transmission, the eNB <b>805</b>D may occasionally send a UL grant to the MTC UE <b>803</b>D for sending CSI feedback. Thus, when the MTC UE <b>803</b>D has not sent CSI for a time period greater than a threshold time period, the eNB <b>805</b>D may send a UL grant. The MTC UE <b>803</b>D may receive the UL grant from the eNB <b>805</b>D and send CSI to the eNB <b>805</b>D based on the received UL grant from the eNB <b>805</b>D. This procedure may be tied to a supervision procedure.

0096There are several approaches for reporting CSI feedback. In a first approach, the MTC UE <b>803</b>D may determine the CSI based on a lowest quality channel estimate over multiple subframes and report the worst CSI (for power optimization). In a second approach, the MTC UE <b>803</b>D may determine the CSI based on an average of the estimated channels over multiple frames and report the average CSI (for spectral efficiency optimization). In a third approach, the MTC UE <b>803</b>D may determine both worst case and average CSI and report both the worse case and average CSI (for eNB scheduling flexibility). In a fourth approach, the MTC UE <b>803</b>D may determine the CSI based on one estimate of the channel among the estimated channels of the multiple subframes. In a fifth approach, the MTC UE <b>803</b>D may receive a configuration indicating how to determine the CSI, and then determine the CSI based on the received configuration. The configuration may indicate to the MTC UE <b>803</b>D to use one of the first through fourth approaches, or may indicate to the MTC UE <b>803</b>D to use a different approach for reporting CSI feedback.

0097If an MBSFN broadcast is used for data transmission, the MTC UE <b>803</b>D may receive information indicating MBSFN subframes, and determine the CSI based on the received information. Thus, the MTC UE <b>803</b>D may be notified of subframes that are transmitted using multicast/broadcast, and the MTC UE <b>803</b>D may treat the CSI feedback differently for those subframes. For example, if the MTC UE <b>803</b>D receives multicast/broadcast data, CSI feedback determined based on the received multicast/broadcast data may better than CSI feedback determined based on a received unicast data. Accordingly, the MTC UE <b>803</b>D may adjust or ignore channel estimates based on multicast/broadcast data.

0098If a decoupled DL and UL operation is used for the MTC UE <b>803</b>D, one cell in the eNB <b>805</b>D may be dedicated for DL while another cell in eNB <b>805</b>D may be dedicated for UL. In this case, the MTC UE <b>803</b>D may receive the data from a first cell of the eNB <b>805</b>D and send CSI to a second cell of the eNB <b>805</b>D, where the second cell is different from the first cell. The first cell of the eNB <b>805</b>D may be a DL serving cell, and the second cell of the eNB <b>805</b>D may be a UL serving cell.

0099As discussed supra, the MTC UE <b>803</b>D may select a RACH format for a RACH procedure based on the CSI. The MTC UE <b>803</b>D sends the CSI through the RACH procedure and indicates the CSI through the selected RACH format. In other words, the MTC UE <b>803</b>D may choose a RACH format (e.g., a different length of a RACH bundle) to indicate to the eNB <b>805</b>D its radio condition, such that the format of RACH indicates the CSI to the eNB <b>805</b>D. For example, if the channel is in a poor condition, the MTC UE <b>803</b>D may select a RACH with a longer transmission time. This RACH format of the longer transmission time indicates to the eNB <b>805</b>D that the channel is in a poor condition. On the other hand, for example, if the channel is in a good condition, the MTC UE <b>803</b>D may select a compact RACH channel, and this RACH format indicates to the eNB <b>805</b>D that the channel is in a good condition. Depending on the RACH format, the eNB <b>805</b>D may select an appropriate MCS and a bundling size for a subsequent DL transmission (e.g., msg2 with bundling).

0100For an initial RACH procedure, the MTC UE <b>803</b>D measures the DL path loss, and depending on the path loss, selects one of multiple RACH sequences/signatures (also referred to as format). If the MTC UE <b>803</b>D selects a normal RACH transmission, then subsequent transmissions by the MTC UE <b>803</b>D (msg3 and msg5) and the eNB <b>805</b>D (msg2 and msg4) do not use TTI bundling. If the MTC UE <b>803</b>D selects a bundled RACH transmission with long TTI, then subsequent transmissions by the MTC UE <b>803</b>D (msg3 and msg5) and the eNB <b>805</b>D (msg2 and msg4) use the lowest MCS (e.g., BPSK) with TTI bundling.

0101The CSI feedback may be combined with other reports. In one approach, the MTC UE <b>803</b>D may receive a periodic supervision message from the eNB <b>805</b>D, and send a response to the eNB <b>805</b>D based on the received periodic supervision message, where the CSI is sent with the response. A periodic supervision may be needed to determine whether the MTC UE <b>803</b>D is accessible or whether the MTC UE <b>803</b>D is out of coverage or out of service (e.g., due to a bad battery). Thus, by sending a periodic supervision message to the MTC UE <b>803</b>D and receiving a response from the MTC UE <b>803</b>D, the eNB <b>805</b>D can determine whether the MTC UE <b>803</b>D is alive. For example, eNB <b>805</b>D may send a periodic supervision message, and if the MTC UE <b>803</b>D sends back an acknowledgement in response to the request, the eNB <b>805</b>D may determine that the MTC UE <b>803</b>D is accessible. MTC UE <b>803</b>D may also send CSI feedback with the acknowledgement to the supervision request.

0102In another approach for combining the CSI with other reports, the MTC UE <b>803</b>D may determine an RSRQ and/or an RSRP, and send the RSRP and/or the RSRQ to the eNB <b>805</b>D, where the CSI is sent with the RSRP and/or the RSRQ. Thus, according to this approach, the MTC UE <b>803</b>D may measure the RSRP and/or the RSRQ and then when the MTC UE <b>803</b>D reports the measured RSRP/RSRQ to the eNB <b>805</b>D, the MTC UE <b>803</b>D may combine the CSI report with RSRP/RSRQ reporting and send the combined report to the eNB <b>805</b>D. The RSRP/RSRQ reporting may be event-driven. Further, the long term CSI reporting may be combined with the RSRP/RSRQ reporting.

0103<figref idref="DRAWINGS">FIG. 9</figref> is a flow chart <b>900</b> of a first method of wireless communication. The method may be performed by a UE. At step <b>902</b>, the UE estimates a channel between a base station and a UE in each of a plurality of subframes. The channel may be averaged over a plurality of subframes. At step <b>904</b>, the UE determines a first MCS that corresponds to the estimated channel between the base station and the UE. At step <b>906</b>, the UE receives data modulated and coded with a second MCS from the base station. At step <b>908</b>, the UE determines whether the second MCS differs from the first MCS by more than a threshold. If the UE determines that the second MCS does not differ from the first MCS by more than a threshold, the UE goes back to step <b>902</b>. If the UE determines that the second MCS differs from the first MCS by more than a threshold, at step <b>912</b>, the UE may determine the CSI. The UE may determine the CSI in step <b>912</b> based on a received configuration in step <b>910</b>. At step <b>914</b>, the UE sends the CSI after determining that the second MCS differs from the first MCS by more than the threshold. At step <b>914</b>, the CSI may be sent in a MAC header within a scheduled UL data transmission. At step <b>914</b>, the CSI may be sent in a MAC header within an UL transmission with a buffer status report.

0104For example, referring to <figref idref="DRAWINGS">FIG. 8A</figref>, the MTC UE <b>803</b>A estimates a channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A in each of a plurality of subframes. The channel may be averaged over a plurality of subframes. The MTC UE <b>803</b>A determines a first MCS that corresponds to the estimated channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A. The MTC UE <b>803</b>A receives data modulated and coded with a second MCS from the eNB <b>805</b>A. The MTC UE <b>803</b>A determines whether the second MCS differs from the first MCS by more than a threshold. If the MTC UE <b>803</b>A determines that the second MCS does not differ from the first MCS by more than a threshold, the MTC UE <b>803</b>A goes back to estimating of a channel between the eNB <b>805</b>A and the MTC UE <b>803</b>A in each of a plurality of subframes. If the MTC UE <b>803</b>A determines that the second MCS differs from the first MCS by more than a threshold, the MTC UE <b>803</b>A determines CSI, and then sends the CSI at the next available opportunity according to the CSI feedback method.

0105In one configuration, the UE sends a request to the base station for sending the CSI upon determining that the second MCS differs from the first MCS by more than the threshold, and receives a response from the base station based on the request. The UE may send the CSI to the base station based on the received response. The request may be a scheduling request and the response may be an UL grant. The scheduling request may request UL resources for sending the CSI. The UE may send the CSI in the requested UL resources. The request may be a random access preamble and the response may be a random access response.

0106In one configuration, the UE receives an UL grant from the base station. The UL grant requests the CSI. The UE sends CSI based on the received UL grant. In one configuration, the UE receives an UL grant from the base station. The UL grant is received when CSI is not sent for a time period greater than a threshold. The UE may send the CSI based on the received UL grant. In one configuration, the estimated channel is averaged over a plurality of subframes. In one configuration, the UE estimates the channel in each of a plurality of subframes, and determines the CSI based on a lowest quality channel estimate over the plurality of subframes. In one configuration, the UE estimates the channel in each of a plurality of subframes, and determines the CSI based on an average of the estimated channels over the plurality of subframes. In one configuration, the CSI includes first CSI corresponding to a lowest quality channel estimate and second CSI corresponding to an average channel estimate. In one configuration, the UE estimates the channel in each of a plurality of subframes, and determines the CSI based on one estimate of the channel. In one configuration, the UE receives a configuration indicating how to determine the CSI, and determines the CSI based on the received configuration. In one configuration, the UE receives information indicating MBSFN subframes, and determines the CSI based on the received information. In one configuration, the data is received from a first cell of the base station and the CSI is sent to a second cell different than the first cell of the base station. In one configuration, the UE selects a RACH format for a RACH procedure based on the CSI. The UE sends the CSI through the RACH procedure and indicates the CSI through the selected RACH format. In one configuration, the UE receives a periodic supervision message from the base station, and sends a response to the base station based on the received periodic supervision message. The UE may send the CSI with the response. In one configuration, the UE determines at least one of an RSRQ or an RSRP, and sends the at least one of the RSRP or the RSRQ to the base station. The UE may send the CSI with the at least one of the RSRP or the RSRQ.

0107<figref idref="DRAWINGS">FIG. 10</figref> is a flow chart <b>1000</b> of a second method of wireless communication. The method may be performed by a UE. At step <b>1002</b>, the UE receives a TTI bundling transmission from a base station. At step <b>1004</b>, the UE decodes a subset of the TTI bundling transmission. At step <b>1006</b>, the UE sends an acknowledgment to the base station to terminate the TTI bundling transmission early upon decoding the subset of the TTI bundling transmission. The CSI is indicated to the base station through a percentage of the TTI bundling transmission received by the UE. At step <b>1008</b>, the UE receives (TTI bundled) data modulated and coded with an MCS from the base station, where the MCS is based on the percentage of the TTI bundling transmission received by the UE. The UE returns to step <b>1004</b> to decode a subset of the TTI bundling transmission received at step <b>1008</b>.

0108For example, referring to <figref idref="DRAWINGS">FIG. 8B</figref>, the MTC UE <b>803</b>B receives a TTI bundling transmission from the eNB <b>805</b>B. The MTC UE <b>803</b>B decodes a subset of the TTI bundling transmission. The MTC UE <b>803</b>B sends an acknowledgment to the eNB <b>805</b>B to terminate the TTI bundling transmission early upon decoding the subset of the TTI bundling transmission. The CSI is indicated to the eNB <b>805</b>B through a percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B. The MTC UE <b>803</b>B receives (TTI bundled) data modulated and coded with an MCS from the eNB <b>805</b>B, where the MCS is based on the percentage of the TTI bundling transmission received by the MTC UE <b>803</b>B.

0109<figref idref="DRAWINGS">FIG. 11</figref> is a flow chart <b>1100</b> of a third method of wireless communication. The method may be performed by a UE. At step <b>1102</b>, the UE sends an UL transmission to a base station. At step <b>1104</b>, the UE receives a data transmission from the base station. The data transmission has at least one of an MCS determined based on the UL transmission or a TTI bundling size determined based on the UL transmission.

0110For example, referring to <figref idref="DRAWINGS">FIG. 8C</figref>, the MTC UE <b>803</b>C sends an UL transmission to the eNB <b>805</b>C. The MTC UE <b>803</b>C receives a data transmission from the eNB <b>805</b>C, the data transmission having at least one of an MCS determined based on the UL transmission or a TTI bundling size determined based on the UL transmission.

0111<figref idref="DRAWINGS">FIG. 12</figref> is a conceptual data flow diagram <b>1200</b> illustrating the data flow between different modules/means/components in an exemplary apparatus <b>1202</b>. The apparatus may be a UE. The apparatus includes a receiving module <b>1204</b> that is configured to receive data from the base station. The apparatus further includes a channel estimation module <b>1206</b> that is configured to estimate a channel between the base station and the UE in each of a plurality of subframes. The estimated channel may be averaged over a plurality of subframes. The apparatus further includes a MCS determination and comparison module <b>1208</b> that is configured to determine a first MCS that corresponds to the estimated channel between the base station and the UE. The MCS determination and comparison module <b>1208</b> is configured to determine a second MCS, and to determine whether the second MCS differs from the first MCS by more than a threshold. The apparatus further includes a CSI determination module <b>1210</b> that is configured to determine the CSI. The CSI determination module <b>1210</b> may receive a configuration indicating how to determine the CSI, and determine the CSI based on the received configuration. In particular, the CSI determination module <b>1210</b> may be configured to determine the CSI based on a lowest quality channel estimate over the plurality of subframes. The CSI determination module <b>1210</b> may also be configured to determine the CSI based on an average of the estimated channels over the plurality of subframes. The CSI determination module <b>1210</b> may also be configured to determine the CSI that includes first CSI corresponding to a lowest quality channel estimate and second CSI corresponding to an average channel estimate. The CSI determination module <b>1210</b> may also be configured to determine the CSI based on one estimate of the channel. The CSI determination module <b>1210</b> may also be configured to receive information indicating MBSFN subframes, and to determine the CSI based on the received information. Further, the data may be received from a first cell of the base station and the CSI may be sent to a second cell different than the first cell of the base station.

0112The apparatus further includes a transmission module <b>1212</b> that is configured to send the CSI after determining that the second MCS differs from the first MCS by more than the threshold. The transmission module <b>1212</b> may also be configured to send the CSI in a MAC header within a scheduled UL data transmission and/or to send the CSI in a MAC header with an UL transmission with a buffer status report. The transmission module <b>1212</b> may also be configured to send a request to the base station for sending the CSI upon determining that the second MCS differs from the first MCS by more than the threshold, and the receiving module <b>1204</b> may also be configured to receive a response from the base station based on the request, where the CSI is sent to the base station based on the received response. The request may be a scheduling request and the response may be an UL grant. The scheduling request may request UL resources for sending the CSI, where the CSI is sent in the requested UL resources via the transmission module <b>1212</b>. The request may also be a random access preamble and the response may be a random access response. The receiving module <b>1204</b> may also configured to receive an UL grant from the base station, the UL grant requesting the CSI, where the CSI is sent based on the received UL grant. The receiving module <b>1204</b> may also configured to receive an UL grant from the base station, the UL grant being received when CSI is not sent for a time period greater than a threshold, where the CSI is sent based on the received UL grant.

0113The transmission module <b>1212</b> may also be configured to select a RACH format for a RACH procedure based on the CSI, where the CSI is sent through the RACH procedure and is indicated through the selected RACH format. The receiving module <b>1204</b> may also be configured to receive a periodic supervision message from the base station, and the transmission module <b>1212</b> may be configured to a response to the base station based on the received periodic supervision message. In an aspect, the CSI may be sent with the response. The apparatus further includes an RSRP/RSRQ module <b>1214</b> that is configured to determining at least one of an RSRQ or an RSRP, and the transmission module <b>1212</b> may be configured to send the at least one of the RSRP or the RSRQ to the base station. In such an aspect, the CSI may be sent with the at least one of the RSRP or the RSRQ.

0114The apparatus may include additional modules that perform each of the steps of the algorithm in the aforementioned flow charts of <figref idref="DRAWINGS">FIGS. 8A and 9</figref>. As such, each step in the aforementioned flow charts of <figref idref="DRAWINGS">FIGS. 8A and 9</figref> may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

0115<figref idref="DRAWINGS">FIG. 13</figref> is a diagram <b>1300</b> illustrating an example of a hardware implementation for an apparatus <b>1202</b>′ employing a processing system <b>1314</b>. The processing system <b>1314</b> may be implemented with a bus architecture, represented generally by the bus <b>1324</b>. The bus <b>1324</b> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <b>1314</b> and the overall design constraints. The bus <b>1324</b> links together various circuits including one or more processors and/or hardware modules, represented by the processor <b>1304</b>, the modules <b>1204</b>, <b>1206</b>, <b>1208</b>, <b>1210</b>, <b>1212</b>, and <b>1214</b> and the computer-readable medium <b>1306</b>. The bus <b>1324</b> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

0116The processing system <b>1314</b> may be coupled to a transceiver <b>1310</b>. The transceiver <b>1310</b> is coupled to one or more antennas <b>1320</b>. The transceiver <b>1310</b> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <b>1310</b> receives a signal from the one or more antennas <b>1320</b>, extracts information from the received signal, and provides the extracted information to the processing system <b>1314</b>, specifically the receiving module <b>1204</b>. In addition, the transceiver <b>1310</b> receives information from the processing system <b>1314</b>, specifically the transmission module <b>1212</b>, and based on the received information, generates a signal to be applied to the one or more antennas <b>1320</b>. The processing system <b>1314</b> includes a processor <b>1304</b> coupled to a computer-readable medium <b>1306</b>. The processor <b>1304</b> is responsible for general processing, including the execution of software stored on the computer-readable medium <b>1306</b>. The software, when executed by the processor <b>1304</b>, causes the processing system <b>1314</b> to perform the various functions described supra for any particular apparatus. The computer-readable medium <b>1306</b> may also be used for storing data that is manipulated by the processor <b>1304</b> when executing software. The processing system further includes at least one of the modules <b>1204</b>, <b>1206</b>, <b>1208</b>, <b>1210</b>, <b>1212</b>, and <b>1214</b>. The modules may be software modules running in the processor <b>1304</b>, resident/stored in the computer readable medium <b>1306</b>, one or more hardware modules coupled to the processor <b>1304</b>, or some combination thereof. The processing system <b>1314</b> may be a component of the UE <b>650</b> and may include the memory <b>660</b> and/or at least one of the TX processor <b>668</b>, the RX processor <b>656</b>, and the controller/processor <b>659</b>.

0117In one configuration, the apparatus <b>1202</b>/<b>1202</b>′ for wireless communication includes means for determining a first MCS that corresponds to an estimated channel between a base station and the UE, means for receiving data modulated and coded with a second MCS from the base station, means for determining whether the second MCS differs from the first MCS by more than a threshold, and means for sending CSI after determining that the second MCS differs from the first MCS by more than the threshold. The apparatus may further include means for sending a request to the base station for sending the CSI upon determining that the second MCS differs from the first MCS by more than the threshold, and means for receiving a response from the base station based on the request. The CSI is sent to the base station based on the received response. The apparatus may further include means for estimating the channel in each of a plurality of subframes, and means for determining the CSI based on a lowest quality channel estimate over the plurality of subframes. The apparatus may further include means for estimating the channel in each of a plurality of subframes, and means for determining the CSI based on an average of the estimated channels over the plurality of subframes. The apparatus may further include means for estimating the channel in each of a plurality of subframes, and means for determining the CSI based on one estimate of the channel. The apparatus may further include means for receiving a configuration indicating how to determine the CSI, and means for determining the CSI based on the received configuration. The apparatus may further include means for receiving information indicating MBSFN subframes, and means for determining the CSI based on the received information. The apparatus may further include means for receiving a periodic supervision message from the base station, and means for sending a response to the base station based on the received periodic supervision message. The CSI is sent with the response. The apparatus may further include means for determining at least one of an RSRQ or an RSRP, and means for sending the at least one of the RSRP or the RSRQ to the base station. The CSI is sent with the at least one of the RSRP or the RSRQ. The aforementioned means may be one or more of the aforementioned modules of the apparatus <b>1202</b> and/or the processing system <b>1314</b> of the apparatus <b>1202</b>′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system <b>1314</b> may include the TX Processor <b>668</b>, the RX Processor <b>656</b>, and the controller/processor <b>659</b>. As such, in one configuration, the aforementioned means may be the TX Processor <b>668</b>, the RX Processor <b>656</b>, and the controller/processor <b>659</b> configured to perform the functions recited by the aforementioned means.

0118<figref idref="DRAWINGS">FIG. 14</figref> is a conceptual data flow diagram <b>1400</b> illustrating the data flow between different modules/means/components in an exemplary apparatus <b>1402</b>. The apparatus may be a UE. The apparatus includes a receiving module <b>1404</b> that is configured to receive a TTI bundling transmission from a base station. The apparatus further includes a decoding module <b>1406</b> that is configured to decode a subset of the TTI bundling transmission. The apparatus further includes a transmission module <b>1408</b> that is configured to send an acknowledgment to the base station to terminate the TTI bundling transmission early upon decoding the subset of the TTI bundling transmission. The CSI is indicated to the base station through a percentage of the TTI bundling transmission received by the UE. The receiving module <b>1404</b> may be configured to receive data modulated and coded with an MCS from the base station, where the MCS is based on the percentage of the TTI bundling transmission received by the UE.

0119Alternatively, the transmission module <b>1408</b> may be configured to send an UL transmission to a base station, and the receiving module <b>1404</b> may be configured to receive a data transmission from the base station, the data transmission having at least one of an MCS determined based on the UL transmission or a TTI bundling size determined based on the UL transmission.

0120The apparatus may include additional modules that perform each of the steps of the algorithm in the aforementioned flow charts of <figref idref="DRAWINGS">FIGS. 8B</figref>, <b>8</b>C, <b>10</b>, and <b>11</b>. As such, each step in the aforementioned flow charts of <figref idref="DRAWINGS">FIGS. 8B</figref>, <b>8</b>C, <b>10</b>, and <b>11</b> may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

0121<figref idref="DRAWINGS">FIG. 15</figref> is a diagram <b>1300</b> illustrating an example of a hardware implementation for an apparatus <b>1402</b>′ employing a processing system <b>1514</b>. The processing system <b>1514</b> may be implemented with a bus architecture, represented generally by the bus <b>1524</b>. The bus <b>1524</b> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <b>1514</b> and the overall design constraints. The bus <b>1524</b> links together various circuits including one or more processors and/or hardware modules, represented by the processor <b>1504</b>, the modules <b>1404</b>, <b>1406</b>, and <b>1408</b>, and the computer-readable medium <b>1506</b>. The bus <b>1524</b> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

0122The processing system <b>1514</b> may be coupled to a transceiver <b>1510</b>. The transceiver <b>1510</b> is coupled to one or more antennas <b>1520</b>. The transceiver <b>1510</b> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <b>1510</b> receives a signal from the one or more antennas <b>1520</b>, extracts information from the received signal, and provides the extracted information to the processing system <b>1514</b>, specifically the receiving module <b>1404</b>. In addition, the transceiver <b>1510</b> receives information from the processing system <b>1514</b>, specifically the transmission module <b>1408</b>, and based on the received information, generates a signal to be applied to the one or more antennas <b>1520</b>. The processing system <b>1514</b> includes a processor <b>1504</b> coupled to a computer-readable medium <b>1506</b>. The processor <b>1504</b> is responsible for general processing, including the execution of software stored on the computer-readable medium <b>1506</b>. The software, when executed by the processor <b>1504</b>, causes the processing system <b>1514</b> to perform the various functions described supra for any particular apparatus. The computer-readable medium <b>1506</b> may also be used for storing data that is manipulated by the processor <b>1504</b> when executing software. The processing system further includes at least one of the modules <b>1404</b>, <b>1406</b>, and <b>1408</b>. The modules may be software modules running in the processor <b>1504</b>, resident/stored in the computer readable medium <b>1506</b>, one or more hardware modules coupled to the processor <b>1504</b>, or some combination thereof. The processing system <b>1514</b> may be a component of the UE <b>650</b> and may include the memory <b>660</b> and/or at least one of the TX processor <b>668</b>, the RX processor <b>656</b>, and the controller/processor <b>659</b>.

0123In one configuration, the apparatus <b>1402</b>/<b>1402</b>′ for wireless communication includes means for receiving a TTI bundling transmission from a base station, means for decoding a subset of the TTI bundling transmission, and means for sending an acknowledgment to the base station to terminate the TTI bundling transmission early upon decoding the subset of the TTI bundling transmission, where CSI is indicated to the base station through a percentage of the TTI bundling transmission received by the UE. The apparatus may further include means for receiving data modulated and coded with an MCS from the base station. The MCS is based on the percentage of the TTI bundling transmission received by the UE.

0124In another configuration, the apparatus <b>1402</b>/<b>1402</b>′ for wireless communication includes means for sending an UL transmission to a base station, and means for receiving a data transmission from the base station, the data transmission having at least one of an MCS determined based on the UL transmission or a TTI bundling size determined based on the UL transmission. The aforementioned means may be one or more of the aforementioned modules of the apparatus <b>1402</b> and/or the processing system <b>1514</b> of the apparatus <b>1402</b>′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system <b>1514</b> may include the TX Processor <b>668</b>, the RX Processor <b>656</b>, and the controller/processor <b>659</b>. As such, in one configuration, the aforementioned means may be the TX Processor <b>668</b>, the RX Processor <b>656</b>, and the controller/processor <b>659</b> configured to perform the functions recited by the aforementioned means.

0125<figref idref="DRAWINGS">FIG. 16</figref> is a flow chart <b>1600</b> of a fourth method of wireless communication. The method may be performed by a UE. At step <b>1602</b>, the UE determines CSI. The CSI may be determined over multiple subframes. At step <b>1604</b>, the UE determines whether to send the CSI based on a timer and/or a threshold. If the UE determines not to send the CSI, the UE goes back to step <b>1602</b>. If the UE determines to send the CSI, at step <b>1606</b>, the UE sends the CSI. The UE may send the CSI in a MAC header upon determining to send the CSI. In an aspect, the CSI may include at least one of a CQI, an RI, a PMI, an MCS, or path loss. The UE's determination to send the CSI based the threshold in step <b>1604</b> may depend on a difference between the CSI and reference CSI. The reference CSI may be determined based on at least one of previously reported CSI, fixed CSI, path loss, or an MCS of a received data transmission from a base station. The UE may send CSI to the base station in an initial connection setup with the base station.

0126For example, referring to <figref idref="DRAWINGS">FIG. 8D</figref>, the MTC UE <b>803</b>D estimates a channel between the eNB <b>805</b>D and the MTC UE <b>803</b>D. The MTC UE <b>803</b>D then determines <b>873</b> CSI that corresponds to the estimated channel between the eNB <b>805</b>D and the MTC UE <b>803</b>D. The MTC UE <b>803</b>D determines whether to send the CSI to the eNB <b>805</b>D based on a threshold T2 and/or a timer. For example, if a difference between the CSI and reference CSI is greater than the threshold T2 and/or the timer expires, the MTC UE <b>803</b>D may determine to send the CSI to the eNB <b>805</b>D. The reference CSI may be CSI that the UE <b>803</b>D has previously reported to the eNB <b>805</b>D prior to determining the CSI. The reference CSI may be a fixed CSI that includes a fixed value as the reference CSI. The reference CSI may be determined based on an MCS of a data transmission received from the eNB <b>805</b>D. If the MTC UE <b>803</b>D determines to send the CSI to the eNB <b>805</b>D, the MTC UE <b>803</b> sends the CSI to the eNB <b>805</b>D in a MAC header.

0127In one configuration, the UE sends a request to the base station for sending the CSI, and receives a response from the base station based on the request. In an aspect, the UE may send the CSI to the base station based on the received response. The request may be a scheduling request or a RACH message and the response is a UL grant. In an aspect, the UE sends the CSI in a scheduled PUSCH of the UL grant. The UE may send the CSI in message 3 or message 5 of a RACH procedure.

0128In one configuration, the UE receives an UL grant from the base station when CSI is not sent for a time period greater than a threshold. In an aspect, the UE may send the CSI based on the received UL grant. In one configuration, the estimated channel is averaged over multiple subframes. In one configuration, the UE estimates the channel in each of multiple subframes, and determines the CSI based on a lowest CSI over the multiple subframes. In one configuration, the UE estimates the channel in each of multiple subframes, and determines the CSI based on an average of the estimated channels over the multiple subframes. In one configuration, the UE receives a configuration indicating how to determine the CSI, and determines the CSI based on the received configuration. In one configuration, the UE receives information indicating MBSFN subframes, and determines the CSI based on the received information. In one configuration, the UE selects a RACH format for a RACH procedure based on the CSI. In an aspect, the UE may send the CSI through the RACH procedure and indicates the CSI through the selected RACH format. In one configuration, the UE receives a periodic supervision message from the base station, and sends a response to the base station based on the received periodic supervision message. In an aspect, the UE may send the CSI with the response. In one configuration, the UE determines at least one of an RSRQ or an RSRP, and sends the at least one of the RSRP or the RSRQ to the base station. In an aspect, the UE may send the CSI with the at least one of the RSRP or the RSRQ. In one configuration, the UE may send the CSI upon expiration of the timer.

0129<figref idref="DRAWINGS">FIG. 17</figref> is a conceptual data flow diagram <b>1700</b> illustrating the data flow between different modules/means/components in an exemplary apparatus <b>1702</b>. The apparatus may be a UE. The apparatus includes a receiving module <b>1704</b> that is configured to receive reference signals from a base station <b>1750</b>. The apparatus further includes a CSI determination module <b>1706</b> that is configured to determine the CSI. The CSI determination module <b>1706</b> may determine the CSI over a plurality of subframes. The CSI determination module <b>1706</b> may be configured to estimate the CSI in each of a plurality of subframes, and to determine the CSI based on a lowest CSI over the plurality of subframes or on an average of the estimated CSI over the plurality of subframes. The CSI determination module <b>1706</b> may receive a configuration indicating how to determine the CSI, and determine the CSI based on the received configuration. The CSI determination module <b>1706</b> may also be configured to receive information indicating MBSFN subframes, and to determine the CSI based on the received information.

0130The apparatus further includes a feedback module <b>1708</b> that is configured to determine whether to send the CSI based on at least one of a timer or a threshold. The apparatus further includes a timer module <b>1710</b> to manage the timer. The feedback module <b>1708</b> may determine to send the CSI based on the threshold depending on a difference between the CSI and reference CSI. The CSI determination module <b>1706</b> may determine the reference CSI based on at least one of previously reported CSI, fixed CSI, path loss, or an MCS of a received data transmission from a base station <b>1750</b>. The feedback module <b>1708</b> may determine to send the CSI upon expiration of the timer indicated by the timer module <b>1710</b>.

0131The apparatus further includes a transmission module <b>1712</b> that is configured to send the CSI upon determining to send the CSI. The transmission module <b>1712</b> may send the CSI in a MAC header upon determining to send the CSI. In an aspect, the CSI may include at least one of a CQI, an RI, a PMI, an MCS, or path loss. The transmission module <b>1712</b> may be configured to send CSI to the base station <b>1750</b> in an initial connection setup with the base station <b>1750</b>. The transmission module <b>1712</b> may also be configured to send a request to the base station <b>1750</b> for sending the CSI, and the receiving module <b>1704</b> may also be configured to receive a response from the base station <b>1750</b> based on the request, where the CSI is sent to the base station <b>1750</b> based on the received response. The request may be a scheduling request or a RACH message and the response may be a UL grant, where the apparatus sends the CSI in a scheduled PUSCH of the UL grant. In an aspect, the transmission module <b>1712</b> may send the CSI in message 3 or message 5 of a RACH procedure. The transmission module <b>1712</b> may also be configured to select a RACH format for a RACH procedure based on the CSI, where the CSI is sent through the RACH procedure and is indicated through the selected RACH format. The receiving module <b>1704</b> may also be configured to receive a periodic supervision message from the base station <b>1750</b>, and the transmission module <b>1712</b> may be configured to send a response to the base station <b>1750</b> based on the received periodic supervision message, where the CSI is sent with the response. The apparatus further includes an RSRP/RSRQ module <b>1714</b> that is configured to determine at least one of an RSRQ or an RSRP, and the transmission module <b>1712</b> may be configured to send the at least one of the RSRP or the RSRQ to the base station <b>1750</b>, where the CSI is sent with the at least one of the RSRP or the RSRQ. The receiving module <b>1704</b> may also configured to receive an UL grant from the base station <b>1750</b>, the UL grant being received when CSI is not sent for a time period greater than a second threshold, where the CSI is sent based on the received UL grant.

0132The apparatus may include additional modules that perform each of the steps of the algorithm in the aforementioned flow chart of <figref idref="DRAWINGS">FIGS. 8D and 16</figref>. As such, each step in the aforementioned flow charts of <figref idref="DRAWINGS">FIGS. 8D and 16</figref> may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

0133<figref idref="DRAWINGS">FIG. 18</figref> is a diagram <b>1800</b> illustrating an example of a hardware implementation for an apparatus <b>1702</b>′ employing a processing system <b>1814</b>. The processing system <b>1814</b> may be implemented with a bus architecture, represented generally by the bus <b>1824</b>. The bus <b>1824</b> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <b>1814</b> and the overall design constraints. The bus <b>1824</b> links together various circuits including one or more processors and/or hardware modules, represented by the processor <b>1804</b>, the modules <b>1704</b>, <b>1706</b>, <b>1708</b>, <b>1710</b>, <b>1712</b>, <b>1714</b>, and the computer-readable medium/memory <b>1806</b>. The bus <b>1824</b> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

0134The processing system <b>1814</b> may be coupled to a transceiver <b>1810</b>. The transceiver <b>1810</b> is coupled to one or more antennas <b>1820</b>. The transceiver <b>1810</b> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <b>1810</b> receives a signal from the one or more antennas <b>1820</b>, extracts information from the received signal, and provides the extracted information to the processing system <b>1814</b>, specifically the receiving module <b>1704</b>. In addition, the transceiver <b>1810</b> receives information from the processing system <b>1814</b>, specifically the transmission module <b>1712</b>, and based on the received information, generates a signal to be applied to the one or more antennas <b>1820</b>. The processing system <b>1814</b> includes a processor <b>1804</b> coupled to a computer-readable medium/memory <b>1806</b>. The processor <b>1804</b> is responsible for general processing, including the execution of software stored on the computer-readable medium/memory <b>1806</b>. The software, when executed by the processor <b>1804</b>, causes the processing system <b>1814</b> to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory <b>1806</b> may also be used for storing data that is manipulated by the processor <b>1804</b> when executing software. The processing system further includes at least one of the modules <b>1704</b>, <b>1706</b>, <b>1708</b>, <b>1710</b>, <b>1712</b>, and <b>1714</b>. The modules may be software modules running in the processor <b>1804</b>, resident/stored in the computer readable medium/memory <b>1806</b>, one or more hardware modules coupled to the processor <b>1804</b>, or some combination thereof. The processing system <b>1814</b> may be a component of the UE <b>650</b> and may include the memory <b>660</b> and/or at least one of the TX processor <b>668</b>, the RX processor <b>656</b>, and the controller/processor <b>659</b>.

0135In one configuration, the apparatus <b>1702</b>/<b>1702</b>′ for wireless communication includes means for determining CSI, means for determining whether to send the CSI based on at least one of a timer or a threshold, and means for sending the CSI upon determining to send the CSI. The apparatus may further include means for sending a request to a base station for sending the CSI and receiving a response from the base station based on the request. In an aspect, the CSI is sent to the base station based on the received response. The apparatus may further include means for receiving an uplink grant from a base station, the uplink grant being received when CSI is not sent for a time period greater than a second threshold. In an aspect, the CSI is sent based on the received uplink grant. The apparatus may further include means for estimating the CSI in each of a plurality of subframes, and means for determining the CSI based on a lowest CSI over the plurality of subframes or on an average of the estimated CSI over the plurality of subframes. The apparatus may further include means for receiving a configuration indicating how to determine the CSI, and means for determining the CSI based on the received configuration. The apparatus may further include means for receiving information indicating MBSFN subframes, and means for determining the CSI based on the received information.

0136The apparatus may further include means for selecting a RACH format for a RACH procedure based on the CSI. In an aspect, the CSI is sent through the RACH procedure and is indicated through the selected RACH format. The apparatus may further include means for receiving a periodic supervision message from a base station, and means for sending a response to the base station based on the received periodic supervision message. In an aspect, the CSI is sent with the response. The apparatus may further include determining at least one of an RSRQ or an RSRP, and means for sending the at least one of the RSRP or the RSRQ to a base station. In an aspect, the CSI is sent with the at least one of the RSRP or the RSRQ. The aforementioned means may be one or more of the aforementioned modules of the apparatus <b>1702</b> and/or the processing system <b>1814</b> of the apparatus <b>1702</b>′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system <b>1814</b> may include the TX Processor <b>668</b>, the RX Processor <b>656</b>, and the controller/processor <b>659</b>. As such, in one configuration, the aforementioned means may be the TX Processor <b>668</b>, the RX Processor <b>656</b>, and the controller/processor <b>659</b> configured to perform the functions recited by the aforementioned means.

0137It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Further, some steps may be combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

0138The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”