Dynamic channel quality reporting in a wireless communication system

ES 2 575 953 T3

DESCRIPTION

Dynamic Channel Quality Reports in a Wireless Communication System

BACKGROUND

I. Field

The present disclosure relates generally to communication and more specifically to techniques for reporting channel quality in a wireless communication system.

II. Background

In a wireless communication system, a transmitter typically processes (eg, encodes and modulates) traffic data to generate output segments. The transmitter then processes the output segments to generate a radio frequency (RF) signal and transmits the RF signal over a wireless channel. The wireless channel distorts the transmitted RF signal with channel response and further degrades the RF signal with noise and interference. A receiver receives the transmitted RF signal and processes the received RF signal to obtain samples. The receiver then processes (eg, demodulates and decodes) the samples to obtain decoded data.

Good performance can be achieved by transmitting data over the wireless channel, so that a high throughput for data transmission can be achieved. To facilitate this, the receiver can estimate the quality of the wireless channel and report the quality of the channel to the transmitter. The transmitter can then adjust its transmission to the receiver based on the reported channel quality, in order to improve throughput, for example, as described in EP1601224 (LUCENT TECHNOLOGIES INC. [US]), November 30, 2005 .

The characteristics of the wireless channel can vary over time due to various factors, such as fading, multipath, interference, etc. The receiver can periodically report channel quality at a sufficiently fast rate to ensure that the transmitter can have up-to-date channel quality information. However, radio resources are consumed to report channel quality to the transmitter. There is, therefore, a need in technology for techniques to effectively report channel quality in a wireless communication system.

SUMMARY

This need is satisfied by the subject matter of the independent claims of the present invention.

Techniques for effectively reporting Channel Quality Indicators (CQI) for wireless communication are described herein. In one aspect, the data activity in a receiver can be determined, and the CQI reports by the receiver can be adjusted, based on the determined data activity. In one design, data activity can be determined based on the expected packet arrivals for a periodic or quasi-periodic transmission to the receiver. CQI reports can be enabled for a time window around each expected packet arrival, and can be suspended outside the time window. In another design, CQI reports can be varied based on feedback of acknowledgments (ACKs) and negative acknowledgments (NACKs), which may be indicative of potential future data activity. For example, CQI reports can be suspended for a predetermined period of time Tg after successfully decoding a packet, and can be resumed at the end of the predetermined period of time. CQI reporting can be enabled after sending a NACK for a decoded packet with errors.

In another design, CQIs can be sent with a first frequency when no data activity is detected, and with a second frequency, greater than the first frequency, when data activity is detected. Data activity can be detected when signaling, or data, is received by the receiver. No data activity can be declared when no signaling or data is received within a predetermined time period Tq from the last signaling or the last data received.

The receiver can operate in a discontinuous transmission (DTX) mode and can be allowed to transmit data and signaling only during periods of DTX ON. In one design, CQIs can be sent only during DTX ON periods, when no data activity is detected, and can be sent during both DTX ON and DTX OFF periods, when data activity is detected. In this design, CQI reports take higher priority than DTX OFF when data activity is detected. CQIs can also be sent with a first frequency and during periods of DTX ON, when no data activity is detected, and can be sent with a second frequency, higher than the first frequency, and during periods of DTX ON and OFF. , when data activity is detected.

ES 2 575 953 T3

Various aspects and features of the disclosure are described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a wireless communication system.

FIG. 2 shows a timing diagram for physical channels in HSDPA.

FIG. 3 shows exemplary transmissions on the downlink and uplink in HSDPA.

FIGs. 4A and 4B show CQI reports for correctly decoded packets.

FIG. 5 shows CQI reports for decoded packets with errors.

FIG. 6 shows CQI reports with different frequencies, depending on data activity.

FIG. 7 shows CQI reports in DTX mode.

FIG. 8 shows a process performed by a receiver, p. eg, a UE.

FIG. 9 shows a process performed by a transmitter, p. e.g., a Node B.

FIG. 10 shows a block diagram of the UE and Node B.

DETAILED DESCRIPTION

FIG. 1 shows a wireless communication system 100 with multiple Node Bs 110 and user equipment (UE) 120. A Node B is generally a fixed station that communicates with UEs and can also be referred to as an evolved Node B (eNB), a base station, an access point, etc. Each Node B 110 provides communication coverage for a specific geographic area and supports communication for UEs within the coverage area. A system controller 130 couples with Node Bs 110 and provides coordination and control for these Node B. System controller 130 may be a single network entity or a collection of network entities.

The UEs 120 can be dispersed throughout the system, and each UE can be static or mobile. A UE can also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, etc. A UE can be a cell phone, a personal digital assistant (PDA), a wireless device, a handheld device, a wireless modem, a laptop, etc.

The techniques described herein can be used for various wireless communication systems, such as Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Multiple Access systems. Frequency Division (FDMA), Orthogonal FDMA (OFDMA) systems, Single Carrier FDMA (SC-FDMA) systems, etc. The terms "system" and "network" are often used interchangeably. A CDMA system can implement radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Broadband CDMA (W-CDMA) and Time Division Synchronous CDMA (TD-SCDMA). cdma2000 covers the IS-2000, IS-95 and IS-856 standards. A TDMA system can implement radio technology such as the Global System for Mobile Communications (GSM). An OFDMA system can implement radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.20, IEEE 802.16 (WiMAX), Flash-OFDM®, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunication System (UMTS). The Long Term Evolution (LTE) of 3GPP is an imminent version of UMTS using E-UTRA, employing OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from an organization called "Collaboration Project of 3^to Generation ”(3GPP). cdma2000 is described in documents coming from an organization called “3rd Generation Collaborative Project 2” (3GPP2). These various radio technologies and standards are known in the art. For clarity, certain aspects of the techniques are described below for UMTS, and 3GPP terminology is used in much of the description below.

In UMTS, the data for a UE can be processed as one or more transport channels in a higher layer. Transport channels can carry data for one or more services, e.g. eg, voice, video, packet data, etc. Transport channels can be mapped to physical channels on a physical layer. Physical channels can be channeled with different channelization codes and can therefore be orthogonal to each other in the code domain.

ES 2 575 953 T3

3GPP Version 5, and later, support High Speed ​​Downlink Packet Access (HSDPA), which is a set of channels and procedures that allow high-speed packet data transmission over the downlink. For HSDPA, a Node B can send data over a High Speed ​​Downlink Shared Channel (HS-DSCH), which is a downlink transport channel, which is shared by UEs both in time and in code. The HS-DSCH can carry data for one or more UEs in each transmission time interval (TTI). HS-DSCH sharing can be dynamic and can change from one TTI to another.

Table 1 lists some downlink and uplink physical channels used for HSDPA, and provides a brief description for each physical channel.

Table 1

<td>Link</td><td>Channel</td><td>Channel name</td><td>Description</td>

<td>Downlink</td><td>HS-PDSCH</td><td>High Speed ​​Downlink Shared Physical Channel</td><td>It carries data sent by the HSDSCH for different UEs.</td>

<td>Downlink</td><td>HS-SCCH</td><td>Shared Control Channel for HS-DSCH</td><td>It carries signaling for the HSPDSCH.</td>

<td>Uplink</td><td>HS-DPCCH</td><td>Dedicated Physical Control Channel for HS-DSCH</td><td>It carries feedback for downlink transmission on HSDPA.</td>

FIG. 2 shows a timing diagram for the physical channels given in Table 1. The transmission timeline is divided into radio frames, each radio frame having a duration of 10 milliseconds (ms). For HSDPA, each radio frame is divided into five sub-frames, each sub-frame has a duration of 2 ms and includes three slots, and each slot has a duration of 0.667 ms. A TTI is equal to one sub-frame for HSDPA and is the smallest unit of time in which a UE can be scheduled and served.

FIG. 2 also shows timing offsets between HS-SCCH, HS-PDSCH, and HS-DPCCH for a UE. The HS-SCCH is aligned by radio frame boundaries. HS-PDSCH begins two slots after HS-SCCH. The HS-DPCCH begins approximately 7.5 slots from the end of a corresponding transmission on the HS-PDSCH.

For HSDPA, a Node B can serve one or more UEs in each TTI. The Node B can send signaling for the scheduled UEs on the HS-SCCH and can send data on the HS-PDSCH two slots later. The signaling can identify the scheduled UEs and the transport format used for each scheduled UE. UEs that can potentially receive data over the HS-PDSCH can process the HS-SCCH to determine whether or not it has been scheduled. The scheduled UEs can further process the HS-PDSCH to retrieve the data sent to these UEs. Scheduled UEs can send ACKs on the HS-DPCCH for correctly decoded packets, or NACKs for decoded packets with errors. A packet can also be referred to as a transport block, a data frame, a data block, etc. The planned and unplanned UEs can send the CQIs over the HS-DPCCH to assist the Node B in transmitting data on the downlink.

For HSDPA, a UE can be configured either for HS-SCCH operation or for operation without HS-SCCH. For HS-SCCH operation, the signaling or scheduling information is sent to the UE on the HS-SCCH two slots prior to transmission of a packet on the HS-PDSCH. The UE can monitor the HS-SCCH to determine whether or not the signaling has been sent to the UE and can process the HS-PDSCH upon detecting signaling on the HS-SCCH. For operation without HS-SCCH, signaling is not sent to the UE on the HS-SCCH prior to transmission of a packet on the HS-PDSCH. The UE can process the HS-PDSCH based on pre-configured parameters to determine whether or not the data has been sent to the UE. For both operations, HS-SCCH or no HS-SCCH, signaling can be sent before a retransmission of a packet to the UE.

FIG. 3 shows exemplary downlink and uplink transmissions for HSDPA. A UE can be configured for HS-SCCH operation in HSDPA and can send CQI on HS-DPCCH in each sub-frame. The UE may not know when it will be served by a Node B. Therefore, the UE can send CQI periodically in each sub-frame so that Node B has updated CQIs for the UE if and when Node B decides to serve the EU.

If the UE is scheduled by the Node B for downlink data transmission in a given sub-frame, then the Node B can use the most recent CQIs from the UE to determine a suitable transport format and transmission power. for data transmission to the UE. The transport format may indicate the modulation scheme, the transport block size, and the set of codes for

ES 2 575 953 T3 pipeline to be used for data transmission to the UE. The Node B can then send signaling (S) to the UE on the HS-SCCH and can send a data packet (Paq) on the HS-PDSCH two slots later.

The UE may process the HS-SCCH in each sub-frame to determine whether or not signaling has been sent for the UE. If the UE is scheduled on a given sub-frame, then the UE can obtain the transport format from the signaling and can then process the HS-PDSCH based on the transport format to retrieve the packet sent to the UE. The UE can then send an ACK if the packet is correctly decoded, or a NACK if not.

FIG. 3 shows the CQIs sent in each subframe. CQIs can also be submitted based on a predetermined CQI reporting pattern, eg. eg, a CQI every 5 ms.

In general, a receiver can send CQIs over a feedback link in a wireless communication system to provide a transmitter with information to select the appropriate parameters (e.g. modulation scheme, code rate, block size , etc.) for data transmission over a data link to the receiver. CQIs can allow the transmitter to send data more efficiently to the receiver. Channel conditions can vary due to various factors, such as movement by the transmitter and / or receiver, external interference, fading and multi-path effects, etc. For good performance, CQIs should accurately reflect the channel conditions at the time data is sent from the transmitter to the receiver. Therefore, CQIs can be sent frequently in order to scan a variable channel. However, sending CQIs frequently can consume a significant amount of radio resources on the feedback link. Therefore, it is desirable to reduce the frequency of CQIs that are sent where possible.

In one aspect, CQI reports can be varied automatically based on data activity in a receiver. Data activity can be determined in a number of ways. In one design, the data activity for a periodic, or quasi-periodic, transmission can be determined based on the expected packet arrivals. Certain applications can send packets at regular intervals, eg. e.g. every 10 ms, 20 ms, etc. Some examples of applications that send periodic transmission include Voice-over-Internet Protocol (VoIP), video telephony which encompasses two-way video and voice communication, and Video-share (VShare) which encompasses voice communication. and video not synchronized. Some examples of quasi-periodic transmission (which may not have strictly periodic behavior) include Silence Descriptor Frames (SIDs) sent during quiet periods, data packets with varying intervals due to clustering of transmissions or retransmissions, etc. For an application that sends a periodic or quasi-periodic transmission, an expected time interval between consecutive packets can be known and referred to as a time between packet arrivals, Tp. Data activity can be expected at or near the time between packet arrivals, from when the last packet was received.

In another design, the data activity can be determined based on the category of the current packet transmission. For example, if a packet is decoded with errors and a NACK is sent, then a retransmission of the packet can be expected soon. On the contrary, if a packet is correctly decoded and an ACK is sent, then a new packet cannot be expected until the next packet arrival time.

In yet another design, data activity can be determined based on a signal received over the data link. For example, if a packet destined for the receiver is detected from the received signal, then more packets may be expected, due to the bursty nature of some applications. This design can be used for non-periodic transmission.

In any case, the CQI reports can be increased whenever data activity is detected, and can be reduced otherwise. For a periodic or quasi-periodic transmission, such as VoIP, CQIs can be sent whenever the transmitter is likely to send packets, and can be skipped when no packet is expected. CQI reports can be dynamically varied in a number of ways, as described below.

In one design, for a periodic or quasi-periodic transmission, such as VoIP, CQIs are not sent for a predetermined period of intercepted time Tg, after the successful reception of a packet. The intercepted time period Tg may be selected to be sufficiently shorter than the inter-packet arrival time Tp so that at least one CQI can be sent for use by the transmitter for the next packet. Tg can also be selected based on the magnitude of arrhythmia at packet arrival times, eg. For example, a longer Tg can be used for a low arrhythmia and a shorter Tg can be used for a large arrhythmia.

FIG. 4A shows a CQI report layout for a UE configured for HS-SCCH operation in HSDPA, for a case where packets are correctly decoded. For clarity, FIG. 4A shows sub-frames with respect to the HS-PDSCH.

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The UE sends the CQIs on the HS-DPCCH in each of sub-frames 0 and 1. Node B uses the CQIs sent in sub-frame 0 to select a transport format for packet A, sends signaling for the UE on HSSCCH in sub-frame 1 and sends packet A on HS-PDSCH in sub-frame 2. The UE suspends sending CQI from sub-frame 2, after receiving the signaling for the packet A in subframe 1. The UE correctly decodes packet A and suspends sending CQI for the intercepted time period Tg from the end of packet A. In the design shown in FIG. 4A, the time between arrival of packets Tp is 20 ms, and the intercepted time period Tg is 13 ms. The UE sends an ACK for packet A in subframe 5.

The intercepted time period Tg ends before sub-frame 10, and the UE sends CQI on the HS-DPCCH in each of sub-frames 10 and 11. Node B uses the CQIs sent in sub-frame 10 to select a transport format for packet B and send packet B on the HS-PDSCH in sub-frame 12. UE suspends sending CQI in sub-frame 12, upon receiving signaling for packet B by HS-SCCH in sub-frame 11 The UE correctly decodes packet B and suspends sending CQI for the time period intercepted Tg, from the end of packet B. The UE sends an ACK for packet B in sub-frame 15. The process can be repeated for each subsequent packet.

FIG. 4B shows a CQI reporting layout by a UE configured for HS-SCCH-free operation in HSDPA, for a case in which packets are correctly decoded. The UE sends the CQIs on the HSDPCCH starting from sub-frame 0. Node B uses the CQIs sent in sub-frame 0 to select a transport format for packet A and sends packet A on the HS-PDSCH in subframe 2. Since the Node B does not send signaling over the HS-SCCH for non-HS-SCCH operation, the UE may attempt to decode the HSDPCCH in each sub-frame. The UE will know that it has been scheduled only after correctly decoding a packet on the HS-DPCCH. The UE correctly decodes packet A and suspends the sending of CQIs for the intercepted time period Tg, starting from the end of packet A. The UE sends an ACK for packet A in subframe 5.

The intercepted time period Tg ends before sub-frame 10, and the UE sends the CQIs on the HS-DPCCH starting at sub-frame 10. Node B uses the CQIs sent in sub-frame 10 to select a transport format for packet B and sends packet B on the HS-PDSCH in sub-frame 12. The UE correctly decodes packet B and suspends the sending of the CQIs during the intercepted time period Tg, starting from end of package B. The UE sends an ACK for packet B in sub-frame 15. The process can be repeated for each subsequent packet.

In the designs shown in FIGs. 4A and 4B, the CQI sent in sub-frame n can be used for a packet sent in sub-frame n + 2. There is therefore a delay of approximately two sub-frames from the moment the CQI is sent to the moment the CQI is used. The intercepted time period Tg can be selected so that a CQI can be sent and made available for use for the next expected packet. In the design shown in FIG. 4A, CQIs can be sent in each sub-frame until detection of signaling for the next packet sent by the HS-PDSCH. In the design shown in FIG. 4B, CQIs can be sent in each sub-frame, until a packet sent on the HS-PDSCH is correctly decoded. These layouts can provide Node B with updated CQIs in the event that the next packet is delayed, e.g. eg, it is sent in subframe 13 or 14 instead of subframe 12.

In another design, CQIs can be sent in a predetermined number of subframes, and then suspended. For example, CQIs can be sent in a sub-frame at the end of the intercepted time period Tg, eg. eg, in sub-frame 10, but not sub-frame 11 or 12. As another example, CQIs may be sent in two sub-frames at the end of the intercepted time period Tg, e.g. eg, in subframes 10 and 11. The number of sub-frames to send the CQIs can be selected based on the magnitude of the arrhythmia in the time between Tp packet arrivals. In general, continuing to send the CQIs until signaling for the next packet is detected can ensure that the updated CQIs are available for the next packet. However, sending the CQIs in a limited number of sub-frames can reduce the amount of overhead on CQI.

The ACK case shown in FIGs. 4A and 4B may occur more frequently and may correspond to good channel conditions. Therefore, a more aggressive CQI intercept can be used for the ACK case.

FIG. 5 shows a CQI reporting design by a UE configured for operation without the HSSCCH in the HSDPA, for a case in which packets are decoded with errors. The UE sends the CQIs on the HS-DPCCH, starting at sub-frame 0. Node B uses the CQIs sent in sub-frame 0 to select a transport format for packet A and sends packet A on the HS-PDSCH in sub-frame 2 UE loses packet A, eg. eg, it did not detect the presence of packet A or it decoded packet A with errors. The UE continues to send the CQIs in each sub-frame and does not send an ACK or a NAK in sub-frame 5.

Node B does not receive an expected ACK or NACK in subframe 5. Node B uses the CQIs sent in subframe 6 to select a transport format for retransmission of packet A in subframe 8. The UE receives signaling on the HS-SCCH in sub-frame 7 and can suspend the sending of CQI from sub-frame 8.

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The UE again decodes packet A with errors. In a first design, the UE continues to suspend the sending of CQI in each sub-frame until a NACK is sent and then begins to send CQI in each sub-frame until signaling is received again on the HS-SCCH. For this design, the UE will suspend the sending of CQI in each of sub-frames 9 to 11, start sending CQI in sub-frame 12 after sending the NACK, and suspend the sending of CQI in sub-frame 14 , after receiving signaling on the HS-SCCH. In a second design, the UE begins to send CQI in each sub-frame until signaling is received on the HS-SCCH. For this design, the UE will send CQI in each of sub-frames 9 to 13 and suspend sending CQI when signaling is received in sub-frame 13. In either case, the UE sends a NACK for packet A in sub-frame 11 and sends CQI in each of sub-frames 12 and 13.

Node B uses the CQIs sent in sub-frame 12 to select a transport format for another retransmission of packet A in sub-frame 14. The UE receives signaling over the HS-SCCH in sub-frame 13 and suspends the sending the CQIs from sub-frame 14. The UE decodes the packet A correctly and can suspend the sending of the CQIs for the intercepted time period Tg, starting from the end of the correctly decoded packet A. The UE sends an ACK for packet A in subframe 17 and resumes sending the CQIs in subframe 22 at the end of the intercepted time period Tg. Tg can be kept at the original value (as shown in FIG. 5) or it can be reduced based on the expected arrival time of the next packet (not shown in FIG. 5).

For simplicity, FIGs. 4A, 4B and 5 show cases in which only one packet is transmitted and retransmitted at a time. Multiple packets can be transmitted in a time-interleaved fashion. In this case, CQI reports can be suspended when all NACKs have been cleared.

The NACK case shown in FIG. 5 may occur less frequently and may correspond to poor canal conditions. Less CQI interception can be used for the NACK case, to better combat bad channel conditions.

In another aspect, the frequency of CQI reporting can be varied, based on whether or not data activity has been detected. A receiver can report CQIs with a first frequency when no data activity is detected and can report CQIs with a second frequency, higher than the first frequency, when data activity is detected. Data activity can be detected based on signaling sent by the HS-SCCH, data sent by the HS-DPCCH, and / or in some other way.

In one design, the receiver may initially operate in a first mode and report CQIs with the first frequency. The receiver can enter a second mode and report CQIs with the second frequency when the receiver detects a transmission sent to the receiver. In one design, the receiver can remain in the second mode as long as a new transmission is detected within a predetermined time period Tq of the last transmission sent to the receiver. Tq can be selected based on various factors, such as the expected time between arrivals of new packages, the desired magnitude of the reduction in CQI overspending, etc. For example, Tq can be set to 10 sub-frames (which is 20 ms) or some other value. The receiver may remain in the second mode for a variable amount of time, which may be dependent on the amount of data activity at the receiver. The receiver can return to the first mode if a transmission has not been received by the receiver within the determined time period Tq.

FIG. 6 shows a layout of CQI reports with different frequencies, depending on the data activity for the HSDPA. A UE sends the CQIs on the HS-DPCCH with a first frequency (eg, every four sub-frames) starting at sub-frame 0. A Node B uses the CQIs sent in sub-frame 0 to select a transport format for packet A and sends packet A on the HS-PDSCH in sub-frame 2. The UE detects packet A that is being sent to the UE based on signaling sent by the HS-SCCH or, for non-HS-SCCH operation, decodes packet A without receiving any signaling on the HS-SCCH. In either case, the UE starts reporting CQIs with a second frequency (eg, each sub-frame). The UE can keep a timer to track the predetermined time period and can reset the timer at Tq at the end of packet A. Tq is set to 16 ms in the example shown in FIG. 6, but it can also be set to other values, eg. eg 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 or infinity. The UE continues to report CQIs with the second frequency until the timer expires.

Node B uses the CQIs sent in sub-frame 7 to select a transport format for packet B and sends packet B on the HS-PDSCH in sub-frame 9. The UE receives packet B before it is it times out, correctly decodes packet B, and resets the timer at Tq at the end of packet B. The UE continues to report CQIs with the second frequency until the timer expires. The timer expires during subframe 18, and the UE starts reporting CQIs with the first frequency from this point onwards.

As shown in FIG. 6, the UE can report the CQIs more frequently as long as new transmissions are detected for the UE within a time Tq of the previous transmission. More frequent CQI reports improve downlink performance.

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A UE may operate in a Continuous Packet Connectivity (CPC) mode, which supports discontinuous transmission (DTX) and discontinuous reception (DRX). In the CPC mode, the UE may be assigned a DTX pattern indicating the ON sub-frames in which the UE can transmit and the OFF sub-frames in which the UE cannot be allowed to transmit. DTX operation can reduce the magnitude of transmit power used by the UE, improve battery life, and reduce uplink interference.

During periods of DTX OFF, the UE may not be allowed to transmit anything on the uplink. DTX DISABLED can take precedence over CQI reports. In this case, CQIs can be sent only if it is time to send CQIs, on the basis that the CQI reporting rules apply AND if the UE is in a DTX ON period. However, sending CQI only during DTX ON periods may not provide sufficiently frequent channel quality feedback and may result in poor HSDPA performance.

In yet another aspect, CQI reports are given higher priority than DTX OFF when determining data activity, e.g. eg, based on any of the techniques described above. A UE can operate in a normal CQI reporting mode when no data activity is determined, or in a priority CQI reporting mode when data activity is determined. In the normal CQI reporting mode, the UE can send the CQIs if it is time to send the CQIs and if the UE is in a DTX ON period. In the priority CQI reporting mode, the UE can send the CQIs if it is time to send the CQIs, regardless of whether the UE is in the DTX ON or OFF period.

In one design, the UE enters the CQI reporting priority mode when the UE detects a transmission sent to the UE. In one design, the UE remains in the priority CQI reporting mode as long as a new transmission is detected within a predetermined time period Tcqi of the last transmission sent to the UE. Tcqi can be selected based on various factors, such as the expected time between arrivals for new packets, the desired magnitude of the reduction in CQI overspending, etc. For example, Tcqi can be set to 10 sub-frames (which is 20 ms) or some other value. The UE may remain in the priority CQI reporting mode for a variable amount of time, which may be dependent on the magnitude of the data activity for the UE. The UE may revert to the normal CQI reporting mode if a transmission has not been sent to the UE within the predetermined time period Tcqi.

FIG. 7 shows a CQI reporting layout by a UE configured with a DTX pattern having a DTX ON period of one sub-frame and a DTX OFF period of four sub-frames. The UE sends the CQIs over the HS-DPCCH with a first frequency and during periods of DTX ON (eg, in sub-frame 0) while operating in the normal CQI reporting mode. Node B uses the CQIs sent in sub-frame 0 to select a transport format for packet A and sends packet A on HS-PDSCH in sub-frame

two. The UE correctly decodes packet A, transitions to priority CQI reporting mode, and begins reporting CQIs with a second frequency (eg, each subframe) and regardless of DTX OFF periods. The UE may maintain a timer to track the predetermined period of time and may reset the timer at Tcqi at the end of packet A. Tcqi is set to 16 ms in the example shown in FIG. 7, but you can also look at other values, p. eg, as indicated above for FIG. 6. The UE continues to report CQIs with the second frequency, regardless of DTX OFF periods, until the timer expires.

Node B uses the CQIs sent in sub-frame 7 to select a transport format for packet B and sends packet B on the HS-PDSCH in sub-frame 9. The UE receives packet B before it is it times out, correctly decodes packet B, and resets the timer at Tcqi at the end of packet B. The UE continues to report CQIs in priority CQI reporting mode until the timer expires. The timer expires during subframe 18, and the UE begins reporting CQIs in the normal CQI reporting mode from this point forward.

As shown in FIG. 7, the UE may report the CQIs regardless of DTX OFF periods, as long as new transmissions are detected for the UE within the time Tcqi of the previous transmission. More frequent CQI reports improve downlink performance.

FIG. 8 shows a design of a process 800 performed by a receiver, p. eg, a UE. The data activity in the receiver can be determined, e.g. eg, based on any of the techniques described above (block 812). CQI reports by the receiver can be adjusted based on the determined data activity (block 814). In one design, data activity can be determined based on expected packet arrivals for a periodic or quasi-periodic transmission to the receiver. CQI reporting can be enabled during a time window around each expected packet arrival, and can be suspended outside of the time window.

CQI reports can be varied based on ACK / NACK feedback, which may be indicative of potential future data activity. In one design, CQI reports can be suspended for a

ES 2 575 953 T3 predetermined time period Tg after correctly decoding a packet, and can be resumed at the end of the predetermined time period Tg. In one design, CQI reports can be suspended after detecting signaling for the receiver, and can be resumed after sending a NACK for an errored decoded packet. Alternatively, CQI reporting can be enabled by recognizing that a packet has been decoded with errors, rather than waiting until a NACK is sent.

In one design, CQIs can be sent with a first frequency, when no data activity is detected, and they can be sent with a second frequency, higher than the first frequency, when data activity is detected. Data activity can be detected when receiving signaling or data from the receiver. No data activity can be declared when no signaling or data is received within a predetermined time period Tq of the last signaling or data received. A timer can be set at the predetermined time period Tq when new signals or data are received. Data activity cannot be declared when the timer expires.

In one design, the receiver can operate in a DTX mode, CQIs can be sent only during periods of DTX ON, when no data activity is detected, and can be sent during periods of DTX both ON and OFF, when detected. data activity. CQIs can also be sent with a first frequency and during periods of DTX ON when no data activity is detected, and can be sent with a second frequency, higher than the first frequency, during periods of DTX ON and OFF, when data activity is detected.

In general, the reporting of channel status information can be adjusted by a receiver based on data activity at the receiver. Channel status information may comprise CQIs, Pre-encoding Control Indication (PCI) used to spatially pre-encode or process data sent from multiple antennas, antenna selection information indicating which antenna (s) ) use to send data, range information indicating the number of data streams to send simultaneously, etc.

FIG. 9 shows a design of a process 900 performed by a transmitter, p. eg, a Node B. CQIs may be received from a receiver, with CQI reports being adjusted by the receiver, based on data activity at the receiver (block 912). The data can be sent to the receiver based on the CQIs received from the receiver (block 914).

A packet can be sent to the receiver, and an ACK, or a NACK, can be received from the receiver for the packet. If an ACK is received, then the CQIs may not be received for a predetermined period of time Tg after the end of the packet. If a NACK is received, then the CQIs can be received immediately after the NACK. CQIs can be received from the receiver with a first frequency, when no data activity is detected at the receiver, or with a second frequency, higher than the first frequency, when data activity is detected at the receiver. The receiver can operate in a DTX mode. CQIs can be received only during periods of DTX ON when no data activity is detected at the receiver, or during periods of both DTX ON and OFF, when data activity is detected at the receiver.

FIG. 10 shows a block diagram of a layout of the UE 120. On the uplink, an encoder 1012 can receive data and signaling (eg, CQIs), to be sent by the UE 120 on the uplink. Encoder 1012 can process (eg, format, encode, and interlace) the data and signaling. A modulator (Mod) 1014 can further process (eg, modulate, channel, and encrypt) the encoded data and signaling, and provide output segments. A transmitter (TMTR) 1022 can condition (e.g. convert to analog, filter, amplify and frequency) the output segments and generate an uplink signal, which can be transmitted via an antenna 1024 to Node Bs .

On the downlink, antenna 1024 can receive downlink signals transmitted by Node B 110 and other Node B. A receiver (RCVR) 1026 can condition (e.g., filter, amplify, down-frequency, and digitize) the signal received from antenna 1024 and provide samples. A demodulator (Demod) 1016 can process (eg, decode, channel, and demodulate) the samples and provide symbol estimates. A decoder 1018 may further process (eg, deinterlace and decode) the symbol estimates and provide decoded data. Encoder 1012, modulator 1014, demodulator 1016, and decoder 1018 can be implemented by a modem processor 1010. These units can perform processing according to radio technology (eg, W-CDMA) used by the system.

A controller / processor 1030 may direct the operation of various units in UE 120. Controller / processor 1030 may implement process 800 in FIG. 8 and / or other processes for reporting CQIs. Memory 1032 can store program codes and data for the UE 120.

FIG. 10 also shows a block diagram of Node B 110, which may be one of the Node Bs in FIG.

1. Within Node B 110, a transmitter / receiver 1038 may support radio communication with UE 120 and other UEs. A 1040 processor / controller can perform various functions for communication with the

ES 2 575 953 T3

EU. Controller / processor 1040 may also implement process 900 in FIG. 9 and / or other processes to receive the CQIs from the UEs and send data to the UEs. Memory 1042 can store program codes and data for Node B 110.

Those skilled in the art will understand that information and signals can be represented using any of a wide variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols and segments that can be mentioned in the full extent of the above description can be represented by voltages, currents, electromagnetic waves, fields or magnetic particles, optical fields or particles, or any combination thereof.

Those of skill will further appreciate that the various logic blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and stages have been described above, generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Skilled craftsmen may implement the described functionality in varying ways for each specific application, but such implementation decisions should not be construed as causing a departure from the scope of the present disclosure.

The various illustrative logic blocks, modules, and circuits described in connection with the disclosure herein may be implemented or realized with a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC). , a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor but, alternatively, the processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, e.g. eg, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a procedure or algorithm described in connection with the disclosure herein can be performed directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory; EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled with the processor so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium can be integrated with the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, functions, such as one or more instructions or code, can be stored on, or transmitted by, a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. A storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, such computer-readable media may 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 media of program code, in the form of instructions or data structures, and which can be accessed by a general-purpose or special-purpose computer, or a general purpose or special purpose processor. Furthermore, any connection is duly called a computer-readable medium. For example, if the software is transmitted from a Web site, server, or other remote source using coaxial cable, fiber optic cable, crossover pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, crossover pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. . Discs as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disc, and blu-ray disc, where some discs usually play data in magnetic form, while other discs reproduce data optically with lasers. Combinations of the above should also fall within the scope of computer-readable media.

The above description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be immediately apparent to

ES 2 575 953 T3 skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Therefore, the disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

In the following, additional examples are described to facilitate understanding of the invention:

In a further example, an apparatus is described, the apparatus comprising at least one processor for determining data activity at a receiver, and for adjusting channel quality indicator (CQI) reports by the receiver, based on the determined data activity; and a memory coupled with said at least one processor is described. Therefore, said at least one processor can determine the data activity based on expected packet arrivals for a periodic or quasi-periodic transmission to the receiver, it can send the CQIs in a time window around each expected packet arrival, and you can suspend CQI reports outside of the time window. Furthermore, said at least one processor can suspend CQI reports for a predetermined period of time after successfully decoding a packet, and can resume CQI reports at the end of the predetermined period of time. Furthermore, said at least one processor can suspend CQI reporting after detecting signaling for the receiver, can decode a packet with errors, and can enable CQI reporting after sending a negative acknowledgment (NACK) for the packet. Said at least one processor can also send the CQIs with a first frequency when no data activity is detected, and can send the CQIs with a second frequency, higher than the first frequency, when data activity is detected. Said at least one processor may further declare that data activity is detected when signaling or data is received, and may declare that no data activity is detected when no signaling or data is received within a predetermined time period of the last signaling. , or the latest data, received. Furthermore, said at least one processor can reset a timer in the predetermined period of time when new signaling or new data is received, and can declare that no data activity is detected when the timer expires. Furthermore, said at least one processor can operate in a discontinuous transmission mode (DTX), can send CQIs only during periods of DTX ON, when no data activity is detected, and can send CQIs during periods of DTX ON and OFF. , when data activity is detected. Said at least one processor can also send the CQIs with a first frequency, and during periods of DTX ON, when no data activity is detected, and can send the CQIs with a second frequency, higher than the first frequency, and during the periods of DTX ON and OFF, when data activity is detected.

In yet another example, a method is described, the method comprising determining data activity in a receiver; and describes the adjustment of the channel quality indicator (CQI) reports by the receiver, based on the determined data activity. Tuning CQI reports can include suspending CQI reports for a predetermined period of time after successfully decoding a packet, and enabling CQI reporting after sending a negative acknowledgment (NACK) for a failed decoded packet. . Furthermore, the tuning of the CQI reports may comprise sending the CQIs with a first frequency when no data activity is detected, and sending the CQIs with a second frequency, higher than the first frequency, when data activity is detected. Determining data activity may comprise declaring that data activity is detected when signaling or data is received, and declaring that no data activity is detected when neither signaling nor data is received within a predetermined time period of the last signaling or the last data received. In addition, the CQI report tuning may comprise sending CQIs only during periods of Discontinuous Transmission (DTX) ON, when no data is detected, and sending CQIs during periods of DTX ON and OFF, when data activity is detected.

In yet another example, an apparatus is described, the apparatus comprising means for determining data activity at a receiver; and describes means for adjusting the channel quality indicator (CQI) reports by the receiver, based on the determined data activity. The means for adjusting the CQI reports may comprise means for suspending the CQI reports for a predetermined period of time, after successfully decoding a packet, and means for enabling the CQI reports after sending a negative acknowledgment (NACK). for a decoded packet with errors. Furthermore, the means for adjusting the CQI reports may comprise means for sending the CQIs with a first frequency, when no data activity is detected, and means for sending the CQIs with a second frequency, higher than the first frequency, when it is detected. data activity. The means for determining data activity may comprise means for declaring that data activity is detected, when signaling or data is received, and means for declaring that no data activity is detected, when no signaling or data is received within a predetermined time period of the last signaling or the last data received. The means for adjusting the CQI reports may comprise means for sending the CQIs only during periods of Discontinuous Transmission (DTX) ON, when no data activity is detected, and means for sending the CQIs during periods of DTX ON and OFF, when detects data activity.

In yet another example, a computer program product is described, the computer program product comprising a computer-readable medium comprising code for making a computer

ES 2 575 953 T3 determine data activity in a receptor; and code is described to cause the computer to adjust the channel quality indicator (CQI) reports by the receiver, based on the determined data activity. The computer-readable medium may further comprise code to cause the computer to suspend CQI reports for a predetermined period of time, after successfully decoding a packet; and code to make the computer enable CQI reporting after sending a negative acknowledgment (NACK) for a decoded packet with errors. Furthermore, the computer-readable medium may comprise code to cause the computer to send the CQIs with a first frequency, when no data activity is detected; and code to cause the computer to send the CQIs with a second frequency, greater than the first frequency, when data activity is detected. The computer-readable medium may further comprise code for causing the computer to declare that data activity is detected when signaling or data is received: and code for causing the computer to declare that no data activity is detected when no signaling or data is received. data within a predetermined time period of the last signaling or the last received data. In addition, the computer-readable medium may comprise code to cause the computer to send CQIs only during periods of Discontinuous Transmission (DTX) ON, when no data activity is detected; and code to cause the computer to send the CQIs during periods of DTX ON and OFF, when data activity is detected.

In yet another example, an apparatus is described, the apparatus comprising at least one processor for determining data activity at a receiver, and for adjusting the notification of channel status information by the receiver, based on the activity of the receiver. determined data; and a memory coupled with at least one processor is described, in which the channel status information comprises at least one of a channel quality indicator (CQI), a pre-encoding control indication (PCI), information on antenna selection and range information.

In yet another example, an apparatus is described, the apparatus comprising at least one processor for receiving channel quality indicators (CQI) from a receiver, wherein the CQI reports by the receiver are adjusted based on the activity of the receiver. data at the receiver, and to send data to the receiver based on the CQIs received from the receiver; and a memory coupled with said at least one processor is described. Said at least one processor may send a packet to the receiver, may not receive any CQIs for a predetermined period of time after the packet, if an acknowledgment (ACK) is received for the packet, and may receive CQIs after an acknowledgment negative receipt (NACK) if the NACK is received for the packet. Said at least one processor can receive CQIs with a first frequency from the receiver, when no data activity is detected at the receiver, and can receive CQIs with a second frequency, higher than the first frequency, from the receiver when it is detected. data activity on the receiver. Furthermore, the receiver may operate in a discontinuous transmission (DTX) mode, wherein said at least one processor may receive CQIs only during periods of DTX ON for the receiver, when no data activity is detected at the receiver, and can receive CQIs during periods of DTX ON and OFF for the receiver, when data activity is detected at the receiver.

In yet another example, a method is described, the method comprising receiving channel quality indicators (CQI) from a receiver, wherein CQI reports by the receiver are adjusted based on data activity at the receiver; and the sending of data to the receiver is described, based on the CQIs received from the receiver. Sending data to the receiver may comprise sending a packet to the receiver, and where receiving the CQIs from the receiver may comprise not receiving any CQIs for a predetermined period of time after the packet, if an acknowledgment (ACK) is received for the packet, and receive the CQIs after a negative acknowledgment (NACK), if the NACK is received for the packet. Furthermore, receiving the CQIs from the receiver may comprise receiving the CQIs with a first frequency from the receiver when no data activity is detected at the receiver, and receiving the CQIs with a second frequency, higher than the first frequency, from the receiver. receiver when data activity is detected on the receiver. Furthermore, receiving the CQIs from the receiver may comprise receiving the CQIs only during periods of Discontinuous Transmission (DTX) ON for the receiver, when no data activity is detected at the receiver, and receiving the CQIs during periods of DTX ON and OFF for the receiver, when data activity is detected on the receiver.