Radio resource assignment in control channel in wireless communication systems

The present invention generally relates to wireless communication. In particular, it relates to a shared channel control channel signaling system in wireless communication systems such as cellular communication networks and their corresponding entities and methods.

In addition to individual and combined coding of control channel signaling schemes that schedule downlink data transmission in LTE (Long Term Evolution) with UMTS Terrestrial Radio Access (UTRA) and UTRAN Network (UTRAN) specifications. Time division multiplexing (TDM) and frequency division multiplexing (FDM) methods have been proposed, including these hybrid methods. In control channel signaling TDM and FDM transmission, downlink and uplink allocation control information can be transmitted over the first few symbols of the downlink frame or spread over the entire length of the frame. The frame period is about 0.5ms, but other periods are possible.

One of ordinary skill in the art will better understand the various aspects, features and advantages of the present disclosure by careful consideration of the detailed description below and the accompanying drawings. These drawings may be simplified for readability and are not necessarily an exact scale.

<p><patcit num="1"><text>International Publication No. 2005/050852</text></patcit></p>

<p> To improve the inefficiency of the form of excess capacity per resource block.</p>

<p> In general, the different frames that make up a radio frame can allocate different parts of the corresponding control channel for radio resource allocation. In one embodiment, the wireless communication device includes a receiver capable of receiving a frame corresponding to a transmission time interval including a control channel and a bit sequence embedded in the frame. A controller communicatively coupled to the receiver is configured to determine part of the control channel for radio resource allocation based on where in the receive frame the corresponding bit sequence is embedded. And part of the control channel for radio resource allocation may be smaller than the entire control channel.</p><p> A wireless communication device such as one of the remote units 103,110 in FIG. 1 receives at least two plurality of frames. Each frame has at least two control channel elements, each containing a bit sequence embedded within the frame. In one embodiment, the radio communication device determines a part of the control channel for allocating radio resources into the frame, respectively, based on where in the frame the corresponding bit sequence is embedded. In general, some of the control channels for radio resource allocation may be smaller than the entire control channel. Each frame can use different parts of the control channel for radio resource allocation, based on where in the frame the corresponding bit sequence is embedded.</p><p> In some examples, all control channel elements of the composite control channel communicate control channel information. In this particular embodiment, the absence of control channel element number information, eg, a bit sequence embedded in the frame, indicates that the entire composite control channel is being used for radio resource allocation. For example, in the absence of control channel element number information, remote units 103,110 can assume that the default number of control channel elements will be used for radio resource allocation.</p>

<figref num="1">The figure which shows the wireless communication system.</figref><figref num="2">Diagram of a radio frame containing a composite control channel with multiple control channel elements.</figref><figref num="3">Diagram of a composite control channel with different types of control channel elements.</figref><figref num="4">flowchart.</figref><figref num="5">Another flowchart.</figref>

FIG. 1 shows a wireless communication system 100. The wireless communication system 100 includes a plurality of base units 101, 102 in charge of cells forming a distributed network over a geographical area. Base units 101, 102 may be referred to as access points, access terminals, node bases, or similar terms known in the art. One or more base units 101 and 102 are responsible for several remote units 103 and 110 within their area or cell, or within their sectors. The remote units 103,110 may also be referred to by a subscriber unit, a mobile unit, a user, a terminal, a subscriber station, a user device (UE), a user terminal or other term known in the art. The network base units 101 and 102 perform functions such as creating a schedule so as to communicate with the remote units 103 and 110 and execute data transmission / reception using the wireless resources available to the terminal. The wireless network also includes management functions such as data routing, participation control, subscriber billing, and terminal authentication that can be controlled by other network entities, as is generally known to those skilled in the art.

Base units 101 and 102 transmit downlink communication signals 104 and 105 to remote units 103, 110 that are responsible for at least a portion of the same resource (time and / or frequency). The remote units 103 and 110 communicate with one or more base units 101 and 102 via uplink communication signals 106 and 113. The one or more base units 101, 102 may include one or more transmitters and one or more receivers responsible for the remote units 103, 110. The number of transmitters in base units 101, 102 may be related to, for example, the number of transmitting antennas 109 in base units 101, 102. Multiple base units 101, 102 can be deployed if multiple antennas are responsible for each sector to provide various advanced communication modes such as adaptive beam formation, transmit diversity, transmit SDMA, and multiple stream transmission. These base units 101, 102 within a sector can be densely integrated and share various hardware and software components. For example, all base units 101, 102 in the same location to share a cell can form what is traditionally known as a base station. The remote units 103,110 can also include one or more transmitters and one or more receivers. The number of transmitters may be related to the number of transmitting antennas in the remote units 103,110.

In one embodiment, the communication system is an OFDMA such as interleaved FDMA (IFDMA), localized FDMA (LFDMA), IFDMA or DFT diffusion OFDM (DFT-SOFDM) including LFDMA function, ie, the next for uplink transmission. Utilizes a generation single carrier based FDMA architecture. In another embodiment, the architecture also includes direct spread CDMA (DS-CDMA), multiple carrier CDMA (MC-CDMA), multiple carrier direct spread CDMA (MC-DS-CDMA), one-dimensional or two-dimensional spread capabilities. Can include orthogonal frequency and code division multiplexing (OFCDM), or simpler time division and frequency division multiplexing / multiple access techniques.

In general, the scheduling entities of the wireless communication network infrastructure, eg, in base units 101 and 102, respectively, in FIG. 1 allocate or allocate wireless resources to remote units 103,110 in the network. Each base unit 101, 102 includes a scheduler that schedules resources and allocates them to remote units 103, 110 within the corresponding area or cell or sector. For example, in the Multiple Access method based on the OFDM method and the long-term development of the 3GPP UTRA / UTRAN research item (also known as Evolved UTRA / UTRAN (EUTRA / EUTRAN)), the time and frequency dimensions are used using the frequency selection (FS) scheduler. Scheduling is executed at. In some embodiments, the remote units 103, 110 enable scheduling by providing a frequency band channel quality indicator (CQI) or other metric to the scheduler, respectively.

In OFDM systems, or OFDM-like systems such as DFT-SOFDM and IFDMA, resource allocation maps the information of a particular base unit 101,102 from a set of available subcarriers determined by the scheduler to subcarrier resources. Frequency and time allocation. This allocation can depend on, for example, the Frequency Selective Channel Quality Indicator (CQI) or other metric reported from the user equipment UE to the scheduler. Channel coding rates and modulation schemes that vary depending on the resource portion of the subcarrier can also be determined by the scheduler and depend on the reported channel quality indicator CQI or other metric. In a code division multiple access network, resource allocation is a code allocation that maps the information of a particular base unit 101,102 from a set of available subcarriers determined by the scheduler to the resources of the subcarrier.

FIG. 2 shows a frame 200 that constitutes a part of the wireless frame. A radio frame generally includes a plurality of frames capable of forming a continuum of connected frames. In FIG. 2, each frame contains a composite control channel section 210 that includes at least two control channel elements. FIG. 2 shows a composite control channel that includes multiple control channel elements 212, 214, 216 and 218. Each control channel element contains a codeword that provides a physical mapping of the logical control channel to a set of symbols, such as the QAM symbol. Control channel elements are generally not of the same type. For example, in FIG. 2, control channel elements 212 and 218 differ in size. The control channel element is also for uplink or downlink allocation and may have different related information payloads. Control channel elements may also be associated with different versions of the specification. In some embodiments, the composite control channel comprises a reference symbol, such as a pilot symbol, that is separate from the control channel element. Reference symbols are usually read by all remote units 103,110.

Each frame corresponds to a transmission time interval TTI. An exemplary transmission time interval TTI is 1 ms. In one embodiment, the length of a single transmission time interval TTI is 1ms or 2ms, and the transmission time interval TTI is segmented into two subframes, each with a length of 0.5ms. However, the above configuration is unless the definition of the resource block RB is extended to automatically define that the resource block RB is extended beyond the full length of the transmit time interval TTI without considering the transmit time interval TTI period. This means that it is necessary to handle multiple resource blocks, that is, more resource blocks than the number of resource blocks in a single 0.5 ms subframe. However, as a result, the inefficiency of the form of excess capacity per resource block RB becomes a problem. If the resource block RB is defined to slightly exceed the length of the transmit time interval TTI, it would be possible to treat each of the resource blocks within multiple subframes that make up the transmit time interval TTI individually. Therefore, in the case of a frame composed of concatenated subframes or a transmission time interval TTI, a mechanism for communicating resource allocation is required. Furthermore, in order to allocate resources based on the needs of individual user equipment UEs, such as less resources allocated to small packets supplied to the user equipment UE and more resources allocated to larger packets supplied to the user equipment UE. Mechanism is needed. For UMTS (Universal Mobile Communication System), the transmission time interval TTI is defined as the length of time a transmission or transport block is transmitted. A transmission block or transport block consists of blocks of data that are coded together to be protected by a single periodic redundancy check CRC. For this example, another definition of transmission time interval TTI may be the length of transmission controlled by a single instance of the control channel signaling scheme.

In one embodiment, each control channel element contains only radio resource allocation information, such as codewords, addressed only to a single radio communication entity, such as one of the remote units 103 or 110 of FIG. Radio resource allocation information includes information specific to other remote units 103,110 and time-frequency radio resource allocation. In another embodiment, the radio resource allocation information can further include modulation, coding rate, information block size, antenna mode index, and other information.

In one embodiment, a wireless communication network infrastructure entity, such as a scheduler, can address multiple control channel elements to the same wireless communication entity, such as one of the remote units 103,110 in FIG. More specifically, the control channel is a codeword that contains the first version of the codeword that contains the resource allocation of the composite control channel to the first control channel element and the codeword that contains the resource allocation of the composite control channel to the second control channel element. It can include a second version, and both the first and second versions of the codeword are addressed to the same mobile unit. In one embodiment, the first and second versions of the codeword are the same, and in another embodiment, the first and second versions of the codeword are different. Whether the codewords addressed to the same entity are different or the same affects how the destination entity joins the control channel elements as described below. Therefore, a wireless communication network infrastructure entity is a composite control channel that contains at least two control channel elements, each of which contains a corresponding first and second codeword version addressed to the same entity. To send. In some examples, a wireless network infrastructure entity typically sends a composite control channel containing a single control channel element addressed to the entity based on the entity's channel state.

In embodiments where the composite control channel comprises a composite control channel that includes at least two different types of radio resource allocation control channel elements, the remote units 103,110 are generally of the control channel elements that make up the composite control channel upon reception of the composite control channel. Determine the number of types. In one embodiment, the composite control channel contains type indicator information for each type of control channel element that constitutes the composite control channel. Therefore, the remote units 103,110 can determine the number of types of control channel elements based on the type indicator information.

In FIG. 3, the radio frame 300 includes a first control channel element type 312 and a composite control channel 310 that includes a second control channel element type 316. The first control channel element type is identified by a first index 314, such as a bit sequence added to the last control channel element of the first type. The second control channel element type is identified by a second indicator 318 added to the last control channel element of the second type. In another embodiment, the first index 314 and the second index 318 are absent and the control channel element type is determined after the control element has been successfully decoded. For example, the type bit can indicate an uplink or downlink control element in the decrypted payload. The control element can be addressed to a single user device UE by a color code cyclic redundancy check CRC or other means. According to another aspect of the present disclosure, the remote units 103,110 determine the number of control channel elements that make up at least one or at least two control channel elements of the composite control channel.

FIG. 3 is the only exemplary embodiment of the physical layout of the control channel elements of the radio subframe. In another embodiment, the layout can be thought of as a logical layout in which the control channel elements include several subcarriers distributed within the frame.

In one embodiment, the step of determining the number of types of control channel elements constituting the composite control channel includes a step of determining the number of uplink control channel elements and a step of determining the number of downlink control channel elements. Including. The number of uplink control channel elements can be determined based on the first bit sequence embedded in the frame, and the number of downlink control channel elements can be determined based on the second bit sequence embedded in the frame. In one embodiment, the number of uplink and downlink control channel elements is determined based on where in the frame the first and second bit sequences are embedded. Alternatively, different bit sequences can be used to indicate different numbers of control channel elements. For example, the first bit sequence can indicate the first number of uplink elements, and the second bit sequence can indicate the second number of uplink elements.

In some embodiments, the composite control channel has a first composite control channel section in the first receive bandwidth on the first center frequency and a second in the second receive bandwidth on the second center frequency. Includes a combined control channel section. The control channel structure can be implemented to accommodate remote users with limited receive bandwidth. More generally, the composite control channel can be divided into a plurality of composite control channel sections on the corresponding center frequencies. For example, the carrier bandwidth is 20MHz, but the terminal can limit its receiver bandwidth to 10MHz. To accommodate such terminals with limited minimum bandwidth capabilities, it is possible to map the composite control channel to both the lower 10MHz subband of the 20MHz carrier and the upper 10MHz subband. It may be necessary in some cases. Terminals with 10MHz capability receive their respective composite control channels by using either the upper or lower subband.

In step S410 of Flowchart 400 of FIG. 4, a wireless communication entity such as a remote unit 103, 110 or a terminal receives a composite control channel that includes at least two control channel elements. In one embodiment, each control channel element contains only radio resource allocation information destined for only a single radio communication entity.

In step S420 of FIG. 4, two or more control channel elements are combined prior to decoding step S430. However, in general, remote units 103,110 may attempt to decode a single control channel element without first combining the elements. You may also attempt to decode a single control channel element after decoding or attempting to decode the combined element. Whether or not a bond is required generally depends on whether the remote units 103,110 have successfully decrypted a single control channel element. Coupling is required, for example, if a single control channel element has a post-decryption Cyclic Redundancy Check (CRC), or other information confirmation check fails, or if the decryption is unsuccessful. Information verification is typically contained within a decoded control channel element, or masked with a coded control channel element, or masked within a periodic redundancy check CRC for color coding of the periodic redundancy check CRC. Contains information specific to remote units 103,110 that have been or are embedded.

In some embodiments, each of the plurality of control channel elements has an associated route index that can be used as the basis for connecting the control channel elements. For example, if a composite control channel contains 12 control channel elements, 4 of these elements can have the same related route indicators to each other and are the basis for decoding, combining, and decoding control channel elements. Can be used as. As described above, in the embodiment in which the control channel is divided into parts on the corresponding center frequency, the remote units 103 and 110 combine only the control channel elements of the same control channel section. In other words, the control channel elements of the control channel parts that are different from each other are not combined.

In some embodiments, the remote units 103,110 combine at least two control channel elements of a composite control channel, each control channel element containing only radio resource allocation information destined for a single radio communication entity. The type. Coupling is required, for example, if a single control channel element has a post-decryption Cyclic Redundancy Check (CRC), or other information confirmation check fails, or if the decryption is unsuccessful. However, in general remote units 103,110 may attempt to decode the control channel element without the initial coupling.

In one embodiment, at least two control channel elements are combined by aggregating the first codeword information and the software information derived from the second codeword information. Here, the first codeword information is in the first control channel element. The second codeword information is in the second control channel element. In such a bond, the combined control channel elements are temporarily aligned and superimposed (known as a chase bond). Superimposition can include maximum ratio coupling, add log-likelihood ratio (LLR), and so on. Here, it is assumed that the first codeword information and the second codeword information are addressed to the same remote unit 103,110. Otherwise, the decryption or post-decryption information verification check will fail. If unsuccessful, the remote units 103,110 can form different combinations of control channel elements, for example by combining different sets of control channel elements or by combining additional elements.

In another embodiment, at least two control channel elements are combined by rearranging and aggregating the first codeword information and the soft information derived from the second codeword information that are different from each other. In this case, the first codeword information is in the first control channel element and the second codeword information is in the second control channel element. For example, the first and second codewords can include a subset of the information set generated by the slow channel encoder and a parity bit. The subsets may be non-overlapping or partially overlapping. The software information corresponding to the overlapping codeword bit positions is usually aggregated in the remote units 103,110, but the non-overlapping bit positions are usually rearranged to appropriate positions in preparation for decoding.

In one embodiment, the remote units 103,110 combine at least two control channel elements according to a predetermined combination of control channel elements. For example, at least one of a given combination includes a combination of at least two logically contiguous control channel elements. The logically continuous control channel elements may or may not be physically continuous. For example, if a set of subcarriers (combs) distributed over frequency is used for one control channel element, another control channel element physically occupies the subcarrier adjacent to the first control channel element. It may or may not be. Alternatively, if the logical and physical order of the subcarriers is the same, that is, if a one-to-one mapping holds between the logical subcarrier and the physical subcarrier, then the logical adjacency means the physical adjacency and vice versa. Is the same. In another embodiment, at least two non-adjacent control channel elements are combined. In this case, the non-adjacent control elements may be physical or logical.

In some embodiments, the order in which the remote units 103,110 attempt to combine control channel elements according to a given combination is based on one or more hypotheses or assumptions. For example, control channel elements can be combined based on a determination of the number of control channel elements that make up a composite control channel. Such a determination step also includes determining the number of control channel elements that make up a particular type of control channel element, in embodiments where the composite control channel comprises the plurality of element types described above. The number of control channel elements can be determined, for example, based on the existence of control channel element number information included in the composite control channel. For example, the number of control channel elements can be determined based on the bit sequence added to the composite control channel. In one embodiment, different bit sequences represent different numbers of control channel elements. In another embodiment, the location of the bit sequence within the frame indicates the number of control channel elements. In the latter embodiment, the same bit sequence can be used to indicate a different number of control channel elements, depending on where the bit sequence is in the frame. Also, the number of control channel elements can be determined based on the data or messages shared between the wireless communication device and the network infrastructure entity. This is done within a message sent to all remote units 103,110 over the occasional broadcast channel, or within a broadcast message sent at the transmission time interval TTI, respectively. The remote unit 103,110 can also transmit the number of control channel elements to be decrypted or a subset of the control channel elements via a message dedicated to the remote unit 103,110.

In one embodiment, the control channel may be one or two control channel elements whose size indicates the type of control element. You can use convolutional coding for control elements. The decoder decodes the first control element, inspects the periodic redundancy check CRC, and ends the decoding when the control element is specified to the user. Otherwise, decoding can start from the point immediately before the tail bit insertion on the first control element and run to the end of the trellis consisting of both control elements. The periodic redundancy check CRC check is executed again. Thus, decoding of the control channel can be achieved with less effort compared to decoding the control elements that were initially coupled to the trellis. Note that in this embodiment, the coding rates of the single and two control elements must be the same.

In some embodiments, a portion of the composite control channel is allocated to allocate radio resources to each frame. In these embodiments, the unallocated portion of the control channel can be used for data transfer. Therefore, a wireless communication network infrastructure entity, such as a scheduler, may allocate a portion of the control channel to allocate wireless resources within each frame by embedding a bit sequence within the corresponding frame. it can. In one embodiment, the location of the bit sequence within the frame indicates the size of the control channel, eg, how many control channel elements are allocated to allocate radio resources to one or more remote units 103,110. In this embodiment, the control channel element can only be addressed to a single remote unit 103,110 or multiple remote units 103,110. More generally, network infrastructure entities to allocate radio resources within a frame, respectively, by modifying the bit sequence or location bit sequence embedded within the frame before sending the frame. , Part of the control channel can be changed dynamically. Moreover, as mentioned above, network infrastructure entities can also dynamically allocate different types of control channel elements and their numbers within a frame.

In another embodiment, it is identified that the control channel element is provided to the remote units 103,110 using a bit sequence embedded within the subframe. In this case, the bit sequence embedded in the subframe may be a data-dependent bit sequence such as a CRC processed by the wireless communication device identification information or a code word masked by the wireless communication device identification information. In this embodiment, the first subframe, which may be the last subframe of the transmit time interval TTI, includes control information including modulation type, resource, or antenna mode index. Each control channel may be one or more control channel elements, and the size of the control channels may be different in the first and second subframes. The second subframe may be in the same control channel part as the control information of the first subframe, or may be in a different part. When using another part of the subframe, the complexity of blind decoding can be reduced by recognizing the control channel elements in the second subframe from the location of the control channel elements in the remote units 103,110 of the first subframe.

In Flowchart 500 of FIG. 5, in step S510, the radio communication network infrastructure entity is part of a control channel to allocate radio resources within each frame by embedding a bit sequence within the corresponding frame. Allocate. The step of allocating a part of the control channel includes the step of allocating all the available parts of the control channel, or less than all the available parts thereof. In this case, the unallocated portion can be used for other purposes such as data transfer.

In step S520, the radio communication network infrastructure entity dynamically modifies part of the control channel to allocate radio resources to each of the multiple frames that make up the radio frame. According to this aspect of the present disclosure, potentially different parts of the control channels within each frame constituting the radio frame can be allocated for radio resource allocation. The part of the control channel for allocating radio resources within each frame can be changed dynamically, either by changing the location of the bit sequences embedded in each frame, or by using different bit sequences, as described above. it can.

At step S530, the radio communication network infrastructure entity transmits at least two frames, such as a radio frame, each containing a control channel partially allocated for radio resource allocation.

For example, FIG. 2 shows the portion of the control channel used for radio resource allocation based on where in the corresponding frame the bit sequence 220, called the end marker or signature, is embedded. Depending on the location of the bit sequence, the number of parts of the control channel used for radio resource allocation, such as the number of elements, may be less than the entire control channel of the frame.

Although the disclosure of the present invention and the best embodiment thereof have been described above so that those skilled in the art can obtain them and carry out and utilize them, the exemplary embodiments disclosed in the present specification include equivalents and are exemplary. It should be appreciated that the disclosure of the invention may be modified and modified without departing from the scope and spirit of the invention, which is limited by the appended claims rather than the embodiments.