HK1177068A - Method performed by a wireless transmit/receive unit (wtru) - Google Patents

Abstract

The present application discloses a method performed by a wireless transmit/receive unit (WTRU), the method comprising: operating, by the WTRU, in a CELL_PCH or URA_PCH state; receiving, by the WTRU, a high speed downlink packet access (HSDPA) radio network temporary identity (H-RNTI) for the WTRU on a high speed shared control channel (HS-SCCH) transmission; performing, by the WTRU, a measurement; transitioning, by the WTRU, to a CELL_FACH state from the CELL_PCH or URA_PCH state on a condition of receiving the H-RNTI for the WTRU; and sending, by the WTRU, a measurement report related to the measurement to a Node-B via a random access channel (RACH) in the CELL_FACH state.

Description

Method for wireless transmit/receive unit (WTRU) execution

The present application is a divisional application of chinese patent application 200780039483.4 entitled "method and apparatus for sending channel quality indications over a shared channel" filed on 19/10/2007.

Technical Field

The present invention relates to wireless communications.

Background

A wireless transmit/receive unit (WTRU) in a Universal Terrestrial Radio Access Network (UTRAN) may be in an idle state or a connected state. Depending on the mobility and activity of the WTRU while the WTRU is in the connected state, the UTRAN may command the WTRU to transition between Cell _ PCH, URA _ PCH, Cell _ FACH, and Cell _ DCH states. User interface communication between the WTRU and the UTRAN is only possible when the WTRU has a Radio Resource Control (RRC) connection to the UTRAN.

On the uplink and downlink, the dedicated channel classifies the Cell _ DCH state. At the WTRU side, this corresponds to continuous transmission and reception and may be requiring user power requirements.

As defined in release 6 of the third generation partnership project (3 GPP), the Cell _ FACH state does not use dedicated channels and thus allows better power consumption at the expense of lower uplink and downlink throughput. In the Cell _ FACH state, uplink communication is achieved through a Random Access Channel (RACH) when downlink communication is through a shared transport channel (e.g., a Forward Access Channel (FACH)) mapped to a second common control physical channel (S-CCPCH). The Cell _ FACH state is suitable for signaling traffic, (e.g., transmission of Cell update and UTRAN Registration Area (URA) update messages), and for applications requiring very low uplink throughput.

While in the Cell _ FACH state, the WTRU may perform signal measurements and/or Traffic Volume Measurements (TVM) as specified in the measurement control information. The signal measurements are used by the WTRU for cell reselection. The TVM is reported to the UTRAN in a measurement report according to the criteria specified in the measurement control information. The measurement report is sent via the RACH.

The RACH is based on the Aloha mechanism at the time slot indicated by the demand. Before sending the RACH message, the WTRU attempts to acquire the channel by sending a short preamble (consisting of a randomly selected signature sequence) in a randomly selected access slot. After transmitting the RACH preamble, the WTRU waits for an acquisition indication from the UTRAN. If no acquisition indication is received, the WTRU ramps up transmit power for the RACH preamble and retransmits the RACH preamble (i.e., sends a randomly selected signature in a selected access slot). If an acquisition indication is received, the WTRU has effectively acquired the channel and may transmit a RACH message. The initial power of the RACH preamble is set based on open loop power control techniques and a ramp-up mechanism is used to further better adjust the transmit power of the WTRU.

It has been proposed to use High Speed Downlink Packet Access (HSDPA) in the Cell _ FACH state. HSDPA is a feature included in the third generation partnership project (3 GPP) release 5 specification. HSDPA operates in the Cell _ DCH state. HSDPA uses three key concepts: adaptive Modulation and Coding (AMC), retransmissions using a hybrid automatic repeat request (HARQ) scheme, and node-B scheduling to enable better use of the downlink shared capacity.

Every two (2) milliseconds, the node-B schedules transmission on the high speed downlink shared channel (HS-DSCH) based on the information it collects from the WTRU and the status of the downlink buffer. In addition, the node-B clips the transmission bit rate of a particular WTRU by adjusting MCS, transport block size, etc. The node-B may transmit at a higher data rate to those WTRUs that perceive favorable channel conditions and at a lower data rate to those WTRUs that perceive unfavorable channel conditions (e.g., at the cell edge).

For HSDPA operation, the node-B needs Channel Quality Indication (CQI) and positive Acknowledgement (ACK)/Negative Acknowledgement (NACK) feedback from the WTRU. The CQI is an index of a table that provides the maximum MCS that the WTRU may support. The CQI is periodically transmitted at a period decided by the UTRAN. The ACK/NACK feedback is used for HARQ processes. The ACK/NACK information is provided only in response to a packet being received in the downlink.

In the 3GPP release 6 specification, CQI and ACK/NACK information is transmitted via a high-speed dedicated physical control channel (HS-DPCCH). Each WTRU is allocated a separate HS-DPCCH and thus the WTRU can easily provide feedback information. Further, the HS-DPCCH is power controlled using an offset to an uplink Dedicated Physical Control Channel (DPCCH), where closed loop power control is performed. The information on the HS-DPCCH is heavily (heavily) coded to assist detection. As more and more WTRUs use HSDPA, the number of feedback control channels increases. Even if these are power controlled, the feedback information may cause uplink noise to rise, thereby reducing the available capacity for other uplink transmissions.

The main problem if HSDPA is used in the Cell _ FACH state is the lack of a dedicated uplink channel to convey CQI and ACK/NACK information. Without the CQI and ACK/NACK information, the advantages of HSDPA are greatly reduced. The 3GPP release 6 specification does not provide support for optimized MCS selection and HS-DSCH scheduling in the Cell _ FACH state.

Accordingly, it would be desirable to provide a method and apparatus for providing CQI information via a shared channel in a Cell _ FACH state.

Disclosure of Invention

The invention discloses a method executed by a wireless transmit/receive unit (WTRU), which comprises the following steps: the WTRU operating in a CELL _ PCH or URA _ PCH state; the WTRU receiving a High Speed Downlink Packet Access (HSDPA) radio network temporary identity (H-RNTI) of the WTRU via a high speed shared control channel (HS-SCCH) transmission; the WTRU performing measurements; transitioning the WTRU from the CELL _ PCH or URA _ PCH state to a CELL _ FACH state on a condition that the H-RNTI of the WTRU is received; and the WTRU sending a measurement report related to the measurement to a node B via a Random Access Channel (RACH) in the CELL _ FACH state.

The invention discloses a wireless transmit/receive unit (WTRU), comprising: a processor configured to transmit a Channel Quality Indication (CQI) at regular intervals on an uplink channel; wherein the processor is further configured to monitor a downlink channel for a Radio Network Temporary Identity (RNTI) associated with the WTRU; wherein the processor is further configured to determine whether a wireless network is requesting the WTRU to transmit CQI in response to detecting the RNTI associated with the WTRU; and wherein the processor is further configured to transmit the CQI to the wireless network in response to determining that the wireless network requested the WTRU to transmit the CQI.

The invention also discloses a method, which comprises the following steps: a wireless transmit/receive unit (WTRU) transmitting a Channel Quality Indication (CQI) at regular intervals on an uplink channel; the WTRU monitoring a downlink channel for a Radio Network Temporary Identity (RNTI) associated with the WTRU; the WTRU determining whether a wireless network is requesting the WTRU to transmit CQI in response to detecting the RNTI associated with the WTRU; and the WTRU transmitting the CQI to the wireless network in response to determining that the wireless network requested the WTRU.

The invention also discloses a wireless network device, which comprises: a processor configured to receive a Channel Quality Indication (CQI) from a wireless transmit/receive unit (WTRU) at regular intervals on an uplink channel; wherein the processor is further configured to transmit a request for the WTRU to transmit CQI on a downlink channel; wherein the request is sent with a Radio Network Temporary Identity (RNTI) associated with the WTRU; and wherein the processor is further configured to receive the CQI from the WTRU in response to the request.

A method and apparatus for transmitting CQI via a shared or common channel when a WTRU is in a Cell _ FACH state and no dedicated channel is allocated for the WTRU. The WTRU performs measurements of at least one parameter and generates a CQI based on the measurements. The WTRU then transmits the CQI via the RACH. The CQI may be transmitted using a RACH preamble. The plurality of signature sequences may be divided into a plurality of groups. The WTRU may select a group based on the CQI and randomly select a signature sequence among signature sequences in the selected group for transmission of the RACH preamble. The CQI may be appended to the preamble. The CQI is transmitted via the control part or the data part of the RACH message. The RACH message may be an RRC measurement report including CQI transmission. The CQI reporting may be triggered by successful decoding of the HS-SCCH transmission.

Drawings

The invention will be understood in more detail in the following description of preferred embodiments, which are given by way of example and can be understood in conjunction with the accompanying drawings:

figure 1 is a block diagram of an example WTRU;

fig. 2 shows CQI appended at the end of RACH preamble;

fig. 3 shows an example of CQI carried in a RACH control message;

fig. 4 shows an example of CQI carried in the RACH header of a RACH message;

FIG. 5 shows an example two-tiered CQI structure; and

fig. 6 shows an example of CQI reporting triggering.

Detailed Description

The term "WTRU" as referred to below includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a Personal Digital Assistant (PDA), a computer, or any other type of user equipment capable of operating in a wireless environment. The term "node-B" as referred to hereinafter includes, but is not limited to, a base station, a site controller, an Access Point (AP), or any other type of interfacing device capable of operating in a wireless environment.

It is to be noted that although the embodiments to be described are in relation to 3GPP High Speed Downlink Packet Access (HSDPA), the invention may be applied to any wireless communication system in which channel quality feedback information needs to be transmitted via a shared/common channel.

Fig. 1 is a block diagram of an example WTRU 100. The WTRU 100 includes a measurement unit 102, a CQI generator 104, and a transceiver 106. It is noted that the WTRU 100 in fig. 1 is provided as an example, not a limitation, and that the WTRU 100 may include any other conventional processing components necessary for wireless transmission and reception. The measurement unit 102 performs measurements of at least one predetermined parameter to provide an estimate of the channel quality perceived by the WTRU 100.

The measured parameter may be the block error rate (BLER) of the downlink transport channel when the WTRU 100 is in the Cell _ FACH state. A high BLER may be interpreted as a downlink transmission rate that is too high. The measurement parameter may be a path loss measured on a downlink reference channel, such as a common pilot channel (CPICH). A high path loss on the downlink may be interpreted as an indication that the downlink transmission rate is too high. The measurement parameter may be a number of preamble ramp ups required before an Acquisition Indication Channel (AICH) receives an acquisition indication. For example, if the WTRU 100 requires many RACH preamble transmission power ramps up, or if the RACH transmission fails, the WTRU 100 may interpret that the channel conditions are poor and require a reduction in the downlink transmission rate. The measurement parameter may be the received power on the CPICH, high speed shared control channel (HS-SCCH), or any other downlink reference channel. By providing an indication of this power, the node-B estimates the path loss and increases or decreases the downlink transmission rate accordingly. The measurement parameter may be an estimate of the signal-to-noise ratio (SNR) measured on any downlink reference channel, such as the CPICH, where noise includes thermal noise that cannot be removed by the WTRU and interference from neighboring cells. The measurement parameter may be the CPICH Ec/N0 (i.e., CPICH Received Signal Code Power (RSCP)/Received Signal Strength Indicator (RSSI)) or the HS-DPDCH measurement of increased RSSI into which the Primary Common Control Physical Channel (PCCPCH) RSCP is converted. Alternatively, the HS-SCCH power may be measured.

Based on the measurement(s) (i.e., the CQI is an encoded version of the measurement), the CQI generator 104 outputs the CQI. One or a combination of any of the above WTRU measurements may be mapped to a CQI value (e.g., an index to a look-up table) and sent to the node-B via one of the feedback mechanisms described in detail below. The CQI value may be sent to the RRC layer for reporting at the RRC layer. The CQI value may be filtered at the RRC layer. The WTRU 100 may also consider its own receiver capabilities to generate CQI when performing the mapping.

The CQI need not be a measured direct coding, but may also be an estimate of the transport block size or maximum data rate that the WTRU can support based on its receiver design and the number of measurements (i.e., the CQI may be a coded version of the transport block size or maximum data rate that the WTRU can support to maintain a target block error rate (BLER)). The maximum transport block size or maximum data rate supported by the WTRU is formatted and encoded to an index value (i.e., CQI value).

Alternatively, the CQI may be a relative up or down command based on the measurements. For example, the relative up/down command may be generated based on the transport block size supported by the WTRU to maintain the target BLER. For example, the WTRU 100 may decide that the channel quality is poor and may request a reduction in the downlink transmission rate to the next lower level. In this case, the granularity of the control may be more than one step (e.g., 3 levels up, 4 levels down). The relative up or down command may indicate an increase or decrease in the maximum transport block size received at the WTRU 100 with sufficient BLER, or an increase or decrease (e.g., in dB) in a measurement (e.g., pathloss) on the channel.

The CQI may have a multi-layered structure. Fig. 5 shows an example two-tier CQI structure. It is noted that fig. 5 is provided as an example, not a limitation, and that any other CQI structure may be implemented. In this example, the CQI value is encoded with five (5) bits. The first two Most Significant Bits (MSB) are used as a coarse CQI, and the three Least Significant Bits (LSB) are used as a fine CQI in each coarse CQI range. CQI reporting via RRC measurement reporting may be used to send coarse CQI (slow update) and physical layer (L1) procedures may be used to send fine CQI (fast update). In slowly changing channel conditions, a coarse CQI is used, while when the rate of changing CQI is faster, CQI may be reported via an L1-based CQI reporting procedure.

Once the CQI is generated, the transceiver 106 transmits the CQI to the node-B. Since there is no dedicated control channel allocated to the WTRU 100 in the Cell _ FACH state, the transceiver 106 sends the CQI information via the RACH or any other contention-based channel that requires the channel that the WTRU first acquires before the initial transmission.

The transmission of CQI provides a fresh and suitable link performance predictor for transmission on the HS-DPDCH. CQI may be sent when the WTRU was previously in URA _ PCH or Cell _ PCH mode and no measurements were performed and no measurements are available to the UTRAN. The CQI may be reported when the WTRU has sent at least one measurement to the UTRAN but has not received any downlink transmission to date. The CQI may be reported when the WTRU has received a transmission for a period of time but the measurement becomes a legacy value. In the latter two cases, the amount of measurement control needed on the HS-DSCH is reduced.

Embodiments of transmitting CQI are disclosed below. According to a first embodiment, the WTRU 100 sends CQI information using a RACH preamble. Conventionally, the WTRU randomly selects a RACH preamble signature sequence among a plurality of signature sequences. According to a first embodiment, the signature sequences are divided into a plurality of groups. The WTRU 100 selects one group based on the CQI and then randomly selects a signature sequence among signature sequences of the selected group. The choice of signature sequence is not completely random but depends on the CQI. For example, if a two (2) bit CQI is used and a total of 16 signature sequences are divided into four groups, each group having four unique signature sequences, the CQI is used to select one of the four (4) groups, and one of the four signature sequences in the selected group is randomly selected. When the node-B decodes the signature sequence, the node-B cross-references the signature sequence number to decide the group and the CQI transmitted.

If the number of CQI indices exceeds 16, the conventional 16-bit preamble signature sequence may be increased from 16 to 2^k(here k)>4) Rather than repeating the selected signature sequence 256 times per preamble, the WTRU 100 repeats the new signature sequence (256/(2)^k-4) ) times.

Alternatively, the CQI may be attached to the end of the RACH preamble. Fig. 2 shows CQI 206 appended to the end of RACH preamble 202. In this example, the transmission of the RACH preamble includes 256 repetitions of the 16-bit signature sequence 204 and the CQI 206. When the node-B detects preamble sequence 202, the node-B retrieves CQI 206 at the end of preamble sequence 202 and sends an acquisition indication. When the node-B decodes the RACH message, a WTRU Identity (ID) may be decided. Alternatively, the WTRU ID may also be appended to the end of the preamble. This allows all the required information to be transmitted in the preamble without the need for subsequent RACH message transmissions.

According to a second embodiment, the CQI is sent over the control part of the RACH message. Fig. 3 shows an example RACH slot format. The 10ms RACH radio frame 300 includes 15 time slots 302. Each slot 302 includes a data portion 310 and a control portion 320 that are transmitted in parallel. Conventionally, the control portion 320 carries pilot bits 322 and TFCI bits 324. According to the second embodiment, CQI 326 is included in control portion 320.

According to the third embodiment, the CQI is transmitted through the data portion 310 of the RACH message. Fig. 4 shows an example RACH header 410 and MAC Service Data Unit (SDU) 420 in RACH message 400. CQI 412 is included in RACH header 410. To include CQI 412 in RACH header 410, the physical layer provides CQI 412 to the MAC layer (MAC-c/sh layer), and the MAC layer adds CQI 412 in MAC header 410. Signaling between the physical layer and the MAC layer may be implemented, for example, through a modified PHY-Status-IND (PHY-Status-IND) primitive.

According to the fourth embodiment, the CQI may be transmitted through an RRC message (e.g., a measurement report message). The CQI is sent to the RRC layer of the WTRU to be included in the RRC message. The CQI may optionally be filtered by the RRC layer before sending the RRC message.

Since the capability of the physical rach (prach) is prioritized, rules are defined for deciding when the transmission of CQI should be replaced. When the WTRU has a MAC SDU for transmission via the RACH (i.e., opportunistic transmission), the WTRU transmits CQI. As described above, the CQI may be transmitted in the RACH preamble or RACH message.

Because opportunistic transmissions rely on the need to transmit information on the uplink and the information does not have to be related to downlink transmissions, the opportunistic transmissions may not be sufficient. To enable CQI reporting in the absence of uplink transmission on the RACH, the WTRU may transmit CQI (i.e., CQI single transmission) even though the WTRU does not have to send MAC SDUs. The TFCI field may be used to signal to the node that the BRACH transmission is a CQI single transmission. For CQI sheet transmission, CQI may be appended to the RACH preamble as shown in fig. 2, or transmitted in the control part or data part of the RACH message.

Alternatively, the triggering criterion may be defined for the transmission of CQI (i.e. single CQI transmission). The CQI is transmitted periodically. Once the WTRU has an active HSDPA connection in the Cell _ FACH state, the WTRU periodically sends a CQI. The WTRU continuously monitors the channel conditions and sends CQI at regular intervals. The rate of CQI reporting is provided to the WTRU as a configuration parameter. The CQI is reported at a random offset to reduce the likelihood of collisions between WTRUs.

The node-B may select the CQI. For example, the WTRU transmits CQI when receiving data for the downlink. If the node-B does not have fresh CQI information, the node-B selects a low MCS or transmits no data at all on this initial downlink transmission (thus reducing interference). The downlink transmission may be on an HS-SCCH destined for the WTRU. In this case, the WTRU monitors the HS-SCCH and triggers transmission of a CQI when the WTRU successfully decodes its address (i.e., HSDPA radio network temporary identity (H-RNTI)) on the HS-SCCH transmission on the downlink.

The WTRU sends CQI when there is a significant change in channel conditions. The WTRU transmits a CQI when the difference between the current CQI (or average CQI) and the last reported CQI exceeds a predetermined value. The WTRU (e.g., RRC) is configured with CQI delta. A CQI report is triggered each time the measured CQI value exceeds the previous CQI value by a CQI increment and for a predefined period of time.

The WTRU sends CQI at the HSDPA connection start time in Cell _ FACH state. The WTRU continuously monitors the channel conditions, but may send CQI after receiving RRC connection setup message for HSPDA channel.

The range of CQIs may be divided into multiple CQI levels with CQI thresholds, and the WTRU may send the CQIs based on a comparison of the measured (or filtered) CQIs to the CQI thresholds. If the measured (or filtered) CQI crosses the CQI threshold (i.e. changes the CQI level) and remains at the new CQI level for a predetermined time, a CQI report is triggered. Fig. 6 illustrates an example of CQI triggering based on comparison to a CQI threshold. It is noted that fig. 6 is provided as an example, not a limitation, and that the CQI range may be divided into any number of levels. In this example, two CQI thresholds are configured and the CQI range is divided into three levels (CQI 1, CQI2, and CQI 3). Initially, the measured CQI belongs to the CQI1 level. At time a, the measured CQI changes to a second level CQI 2. At this point, a timer is set to trigger CQI reporting. The measured CQI remains at the CQI2 level until the timer expires and thus triggers a CQI report when the timer expires. At time B, the measured CQI changes to a CQI1 level and a timer is set again. The CQI measured before the timer expires changes to a CQI2 level. Thus, the CQI is not transmitted at this time. At time C, the measured CQI changes to a CQI3 level and a timer is set. The measured CQI remains at the CQI3 level until the timer expires and triggers a CQI report at the expiration of the timer.

CQI reporting may be triggered based on specific WTRU actions. For example. The CQI is sent when the WTRU changes to a Cell _ FACH state and/or Cell reselection in any of a Cell _ FACH, Cell _ PCH, and URA _ PCH states.

CQI reporting may be triggered based on downlink reception (e.g., sent when the WTRU fails to decode the downlink reception), and CQI may be sent along with RRC and/or Radio Link Control (RLC) ACK/NACK information. The CQI reporting trigger rate may be adjusted based on the NACK count. The reporting rate is increased when the NACK count increases and the reporting rate is decreased when the ACK count increases.

When data or control information is expected to be received based on the transport block BLER and no data or control information (i.e., HS-SCCH transmission) is received, CQI reporting may be triggered based on the HARQ BLER.

The CQI reporting may be triggered based on the HS-SCCH reception. Once the WTRU successfully decodes the HS-SCCH transmission, the WTRU expects a data transmission on the relevant HS-PDSCH. After correctly decoding the HS-SCCH transmission, a CQI report may be triggered if the WTRU is unable to recover the HS-PDSCH transmission. The triggering mechanism may be based on an averaging window such that CQI reporting is triggered on M occurrences of N observations. M and N may be hardware encoded or network configurable.

Alternatively, the CQI reporting is triggered by counting the number of successful HS-SCCH transmissions (K) in the observation window. The observation window is initiated at the first decoding of the HS-SCCH transmission with a new data indicator indicating a new transport block. The observation window should be large enough to include all retransmissions expected by each transmitted packet. The observation window should be terminated when the next HS-SCCH transmission with a new data indicator arrives. When K is less than the maximum number of retransmissions configured for HSDPA on Cell _ FACH, CQI is triggered. The value of K and the size of the observation window are network configurable. The trigger may be based on an averaging window.

Alternatively, CQI reporting may be triggered after correctly decoding HS-SCCH transmissions and recovering the packets on HS-PDSCH after L retransmissions, where L is less than the maximum number of retransmissions configured for HSDPA on Cell _ FACH. The parameter L may be hardware encoded or network configurable. This event implies that the current MCS is too conservative. The trigger may be based on an averaging window.

CQI reporting may be triggered based on inactivity on the HS-SCCH. After decoding the HS-SCCH, the WTRU may start a timer and trigger a CQI report if the WTRU fails to receive any HSDPA transmission until the timer expires. The timer value may be hardware encoded or network configurable.

The aforementioned threshold and timer values may be defined as part of the system information. The threshold and timer values may be redefined. To reduce the downlink signaling load to specify these new threshold and timer values via RRC signaling, the threshold and timer values may be automatically changed by the WTRU based on RRC and/or RLC ACK/NACK information. The threshold may be linear, asymmetric, or logarithmic (with better granularity for a particular level at the expense of others). The threshold may be automatically changed by the WTRU based on the harq bler.

Downlink control signaling in the Cell _ FACH state may control CQI reporting. The downlink control signaling may be sent through HS-SCCH, MAC-HS header, physical layer signaling, downlink L2 control channel, etc.

The transmission of CQI via RACH may be configured by higher layer signaling (e.g., layer 3 signaling). Such configurations include the signature sequence used by the WTRU for transmission of the RACH preamble, the slot format, the channelization and scrambling codes used by the WTRU for transmission of the PRACH, and so on.

The network may learn the capabilities of different WTRUs and decide whether the WTRU has the capability to send CQI over PRACH/RACH. The network may send configuration parameters to the WTRU based on the WTRU capabilities. The configuration parameters may be sent by adding a number of new Information Elements (IEs) to the regular System Information Blocks (SIBs) in the BCCH, new SIBs (and scheduling) defined in the BCCH, or an IE to an RRC CONNECTION SETUP (RRC CONNECTION SETUP) message when the HSDPA channel is established. New measurements may fall under the "quality measurement" directory and apply to WTRUs in the Cell _ FACH state. The configuration parameters include the method of sending CQI information (via RACH, via L1-based approach, using coarse or fine CQI, etc.), CQI reporting parameters, CQI filtering coefficients (layer 3 filtering for CQI values), CQI reporting criteria (i.e., timers and thresholds), etc.

For backward compatibility, the node-B may be alerted that the WTRU is sending CQI over the RACH (i.e., that the RACH transmission includes CQI). To distinguish RACH transmissions that include CQI, a new signature sequence may be defined for CQI reporting purposes, or a specific signature sequence may be reserved for node-B to distinguish RACH transmissions that include CQI from RACH transmissions that do not. Alternatively, for RACH transmission including CQI, one or more values of the TFCI field (or any field in the RACH header) of the control portion of the RACH message may be reserved. As another alternative, a set of channelization and scrambling codes may be reserved for RACH transmissions that include CQI.

The invention is applicable to WTRUs in Cell _ PCH and URA _ PCH states. In these states, the measurements used for CQI calculation do not have to be continuously updated, but may be monitored for the expected reception of the Paging Indicator Channel (PICH) transitioning to the Cell _ FACH state. This will allow the WTRU to remain in a power saving state and only make measurements when needed.

Examples

1. A method of transmitting CQI via a shared channel.

2. The method of embodiment 1 comprising the WTRU performing measurements of at least one parameter.

3. The method of embodiment 2 comprising the WTRU generating CQI based on the measurements.

4. The method of embodiment 3 comprising the WTRU transmitting the CQI via a contention-based uplink shared channel.

5. The method of embodiment 4 wherein the contention-based uplink shared channel is the RACH.

6. The method as in any one of embodiments 2-5 wherein the measurement used to generate the CQI is at least one of a measured BLER, a pathloss on a downlink reference channel, a measured SNR on a downlink reference channel, a CPICH Ec/N0, a number of RACH preamble ramp ups required for RACH transmission, and a received power on a downlink reference channel.

7. The method as in any one of embodiments 3-6 wherein the CQI is a coded version of at least one of a maximum data rate and a transport block size supported by the WTRU to maintain a target BLER.

8. The method as in any of embodiments 3-6 wherein the CQI is a relative up/down command.

9. The method of embodiment 8 wherein the relative up/down commands are generated based on the WTRU in order to maintain at least one of a transport block size and a maximum data rate supported by BLER.

10. The method as in any one of embodiments 5-9 wherein the CQI is transmitted using a RACH preamble.

11. The method of embodiment 10 wherein a plurality of signature sequences are divided into a plurality of groups and the WTRU selects one group based on the CQI and randomly selects a signature sequence among the signature sequences of the selected group for transmission of a RACH preamble.

12. The method of embodiment 10 wherein the CQI is appended to a RACH preamble.

13. The method of embodiment 12 wherein a WTRU identity is appended to a RACH preamble.

14. The method as in any one of embodiments 5-9 wherein the CQI is transmitted via at least one of a control portion of the RACH message and a data portion of the RACH message.

15. The method as in embodiment 14 wherein at least one value in the TFCI field is reserved for RACH messages containing CQI so that the node-B distinguishes RACH transmissions including CQI from RACH transmissions not including CQI.

16. The method of embodiments 5-9 wherein the CQI is transmitted with the RACH MAC SDU.

17. The method of embodiment 16 wherein the CQI is signaled from the physical layer to the MAC layer via a PHY-Status-IND primitive.

18. The method as in any of embodiments 4-17 wherein the WTRU transmits the CQI periodically.

19. The method of embodiment 18 wherein CQIs are sent with random offsets to reduce the likelihood of collisions between WTRUs.

20. The method as in any one of embodiments 4-19 wherein the WTRU transmits CQI in response to a downlink transmission from the node-B.

21. The method of embodiment 20 wherein the node-B uses a low Modulation Coding Scheme (MCS) for downlink transmission.

22. The method as in any one of embodiments 20-21 wherein the node-B does not transmit data on a downlink transmission.

23. The method as in any one of embodiments 4-22 wherein the WTRU transmits CQI when the WTRU successfully decodes the HS-SCCH transmission.

24. The method of embodiment 23 wherein the WTRU sends the CQI via an RRC measurement report.

25. The method as in any of embodiments 4-24 wherein the WTRU transmits the CQI when a change in channel conditions exceeds a predetermined threshold for a predetermined period of time.

26. The method as in any one of embodiments 4-25 wherein a CQI range is divided into a plurality of CQI levels with CQI thresholds and the CQI is sent when the CQI crosses a CQI threshold and remains at a new CQI level for a predetermined period of time.

27. The method as in any embodiments 4-26 wherein the WTRU transmits the CQI when the CQI is in a certain region of CQI statistics.

28. The method as in any one of embodiments 4-27 wherein the WTRU transmits CQI based on control information received from a node-B.

29. The method of embodiment 28 wherein control information is transmitted to the WTRU via at least one of HS-SCCH, MAC header, physical layer signaling, layer 2 control signaling, connection setup message, and BCCH.

30. The method as in any one of embodiments 5-29 wherein a signature sequence set is reserved for transmitting CQI via RACH in order for a node-B to distinguish RACH transmissions that include CQI from RACH transmissions that do not include CQI.

31. A method as in any of embodiments 5-30 wherein a set of channelization and scrambling codes are reserved for transmitting CQI via a RACH such that a node-B distinguishes between RACH transmissions that include CQI and RACH transmissions that do not include CQI.

32. The method as in any one of embodiments 4-31 wherein the CQI is sent via an RRC message at an RRC layer.

33. The method of embodiment 32 wherein the CQI is filtered at the RRC layer.

34. The method as in any one of embodiments 3-33 wherein the CQI has a multi-layered structure such that the coarse CQI and the fine CQI are transmitted separately.

35. The method of embodiment 34 wherein the coarse CQI is sent via RRC message and the fine CQI is sent via L1 signaling.

36. A method as in any of embodiments 4-35 wherein CQI is sent at the start of an HSDPA connection in a Cell _ FACH state.

37. The method as in any one of embodiments 4-36 wherein a CQI is sent when the WTRU changes to a Cell _ FACH state.

38. The method as in any one of embodiments 4-37 wherein the CQI is sent upon Cell reselection when the WTRU is in one of Cell _ FACH, Cell _ PCH and URA _ PCH states.

39. The method as in any one of embodiments 4-38 wherein a CQI is sent when a WTRU fails to decode a downlink transmission.

40. The method as in embodiment 39 wherein the CQI reporting rate is adjusted based on the count of NACKs and ACKs.

41. The method as in any one of embodiments 4-40 wherein the CQI is sent when it is desired to receive data or control information without data or control information being received.

42. The method as in any one of embodiments 4-41 wherein after correctly decoding the HS-SCCH transmission, a CQI is sent if the WTRU is unable to recover the HS-PDSCH transmission.

43. The method as in any of the embodiments 4-42 wherein the CQI is sent after K unsuccessful decodings of the HS-SCCH transmissions within an observation window.

44. A method as in any of the embodiments 4-43 wherein CQI is sent after correctly decoding an HS-SCCH transmission and recovering the packet on the HS-PDSCH after L retransmissions.

45. The method as in any of embodiments 4-44 wherein after decoding the HS-SCCH transmission, if the WTRU fails to receive any HSDPA transmissions for a predetermined period of time, then a CQI is sent.

46. The method as in any one of embodiments 4-45 wherein the WTRU changes parameters for automatically sending CQI based on RRC and RLC ACK/NACK information.

47. A method as in any of embodiments 5-46 wherein CQI transmission via RACH is configured by higher layer signaling.

48. A WTRU that sends a Channel Quality Indication (CQI) via a shared channel.

49. The WTRU of embodiment 48 comprising: a measurement unit for performing a measurement of at least one parameter.

50. The WTRU of embodiment 49 comprising: a CQI generator for generating a CQI based on the measurement.

51. The WTRU of embodiment 50, comprising: a transceiver for transmitting the CQI via a contention-based uplink shared channel.

52. The WTRU of embodiment 51 wherein the contention-based uplink shared channel is a RACH.

53. The WTRU as in any one of embodiments 50-52, wherein the measurement used to generate the CQI is at least one of a measured BLER, a pathloss on a downlink reference channel, a measured SNR on the downlink reference channel, a CPICH Ec/N0, a number of RACH preamble ramp ups required for RACH transmission, and a received power on the downlink reference channel.

54. The WTRU as in any one of embodiments 50-53 wherein the CQI is a coded version of at least one of a transport block size and a maximum data rate that the WTRU supports to maintain a target BLER.

55. The WTRU as in any one of embodiments 50-53 wherein the CQI is a relative up/down command.

56. The WTRU as in embodiment 55 wherein the relative up/down commands are generated based on at least one of a maximum data rate and a transport block size supported by the WTRU to maintain the target BLER.

57. The WTRU as in any one of embodiments 52-56 wherein CQI is transmitted using a RACH preamble.

58. The WTRU of embodiment 57 wherein a plurality of signature sequences are divided into a plurality of groups and the WTRU selects one group based on the CQI and randomly selects a signature sequence among the signature sequences of the selected group for transmission of a RACH preamble.

59. The WTRU as in any one of embodiments 57-58 wherein the CQI is appended to a RACH preamble.

60. A WTRU according to any of embodiments 57-59, wherein a WTRU identity is attached to a RACH preamble.

61. A WTRU according to any of embodiments 52-56, wherein the CQI is transmitted via at least one of a control portion of a RACH message and a data portion of the RACH message.

62. The WTRU of embodiment 61 wherein at least one value in the TFCI field is reserved for RACH messages including CQI so that the node-B distinguishes RACH transmissions including CQI from RACH transmissions not including CQI.

63. A WTRU according to any of embodiments 61-62, wherein the CQI is transmitted with a RACHMAC SDU.

64. The WTRU of embodiment 63 wherein the CQI is signaled from the physical layer to the MAC layer via a PHY-Status-IND primitive.

65. The WTRU as in any one of embodiments 51-64 wherein the WTRU transmits the CQI periodically.

66. The WTRU of embodiment 65 wherein CQIs are sent with random offsets to reduce the likelihood of collisions between WTRUs.

67. The WTRU as in any one of embodiments 51-66 wherein the WTRU transmits CQI in response to a downlink transmission from a node-B.

68. The WTRU of embodiment 67 wherein the node-B uses a low MCS for downlink transmission.

69. A WTRU according to any of embodiments 67-68, wherein a node-B does not transmit data on a downlink transmission.

70. A WTRU as in any of embodiments 51-69 wherein the WTRU transmits a CQI when the WTRU successfully decodes an HS-SCCH transmission.

71. The WTRU of embodiment 64 wherein the WTRU sends the CQI via an RRC measurement report.

72. The WTRU as in any one of embodiments 51-71, wherein the WTRU transmits the CQI when a change in channel conditions exceeds a predetermined threshold for a predetermined period of time.

73. The WTRU as in any one of embodiments 51-72 wherein the CQI range is divided into a plurality of CQI levels with CQI thresholds and the CQI is sent when the CQI crosses a CQI threshold and remains at a new CQI level for a predetermined period of time.

74. The WTRU as in any one of embodiments 51-73 wherein the WTRU transmits a CQI when the CQI is in a particular region of CQI statistics.

75. The WTRU as in any one of embodiments 51-74 wherein the WTRU transmits a CQI based on control information received from a node-B.

76. The WTRU of embodiment 75 wherein the control information is transmitted to the WTRU via at least one of HS-SCCH, MAC header, physical layer signaling, layer 2 control signaling, connection setup message, and BCCH.

77. A WTRU according to any of embodiments 52-76, wherein a signature sequence set is reserved for transmitting CQI via a RACH, such that a node-B distinguishes between RACH transmissions that include CQI and RACH transmissions that do not include CQI.

78. A WTRU according to any of embodiments 52-77, wherein a set of channelization and scrambling codes is reserved for transmitting CQI via a RACH, such that a node-B distinguishes between RACH transmissions that include CQI and RACH transmissions that do not include CQI.

79. The WTRU as in any one of embodiments 51-78 wherein the CQI is sent via an RRC message on an RRC layer.

80. The WTRU of embodiment 79 wherein the CQI is filtered on the RRC layer.

81. The WTRU as in any one of embodiments 51-80 wherein the CQI has a multi-layered structure such that a coarse CQI and a fine CQI are transmitted separately.

82. The WTRU of embodiment 81 wherein the coarse CQI is sent via RRC message and the fine CQI is sent via L1 signaling.

83. A WTRU as in any one of embodiments 51-82 wherein CQI is sent at the start of an HSDPA connection in a Cell _ FACH state.

84. The WTRU as in any one of embodiments 51-83 wherein a CQI is sent when the WTRU changes to a Cell _ FACH state.

85. The WTRU as in any one of embodiments 51-84 wherein the CQI is sent upon Cell reselection when the WTRU is in one of Cell _ FACH, Cell _ PCH and URA _ PCH states.

86. The WTRU as in any one of embodiments 51-85 wherein a CQI is sent when the WTRU fails to decode a downlink transmission.

87. The WTRU as in embodiment 86 wherein the CQI reporting rate is adjusted based on the count of NACKs and ACKs.

88. The WTRU as in any one of embodiments 51-78 wherein the CQI is sent when it is desired to receive data or control information without data or control information being received.

89. The WTRU as in any of embodiments 51-88 wherein after correctly decoding the HS-SCCH transmission, a CQI is sent if the WTRU is unable to recover the HS-PDSCH transmission.

90. The WTRU as in any of embodiments 51-89 wherein the CQI is sent after K unsuccessfully decoded HS-SCCH transmissions within an observation window.

91. A WTRU according to any of embodiments 51-90, wherein a CQI is sent after correctly decoding an HS-SCCH transmission and recovering a packet on the HS-PDSCH after L retransmissions.

92. The WTRU as in any of embodiments 51-91 wherein after decoding the HS-SCCH transmission, a CQI is sent if the WTRU fails to receive any HSDPA transmissions for a predetermined period of time.

93. The WTRU as in any one of embodiments 51-92 wherein the WTRU changes parameters for automatically sending CQI based on RRC and RLC ACK/NACK information.

94. The WTRU as in any one of embodiments 52-93 wherein CQI transmission via RACH is configured by higher layer signaling.

Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in the present invention may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of the computer-readable storage medium include read-only memory (ROM), random-access memory (RAM), registers, buffer memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM discs and Digital Versatile Discs (DVDs).

For example, suitable processors include: a general-purpose processor, a special-purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any Integrated Circuit (IC), and/or a state machine.

A processor in association with software may be used to implement a radio frequency transceiver for use in a Wireless Transmit Receive Unit (WTRU), User Equipment (UE), terminal, base station, Radio Network Controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a video phone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, and BluetoothA module, a Frequency Modulation (FM) radio unit, a Liquid Crystal Display (LCD) display unit, an Organic Light Emitting Diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any Wireless Local Area Network (WLAN) module.

Claims (5)

1. A method performed by a wireless transmit/receive unit (WTRU), the method comprising:

the WTRU operating in a CELL _ PCH or URA _ PCH state;

the WTRU receiving a High Speed Downlink Packet Access (HSDPA) radio network temporary identity (H-RNTI) of the WTRU via a high speed shared control channel (HS-SCCH) transmission;

the WTRU performing measurements;

transitioning the WTRU from the CELL _ PCH or URA _ PCH state to a CELL _ FACH state on a condition that the H-RNTI of the WTRU is received; and

the WTRU sending a measurement report related to the measurement to a node B via a Random Access Channel (RACH) in the CELL _ FACH state.

2. The method of claim 1, wherein the measurement report comprises at least one of: measured block error rate (BLER), pathloss on a downlink reference channel, measured signal-to-noise ratio (SNR) on a downlink reference channel, received signal power of a common pilot channel (CPICH), Ec/N0 of the CPICH, number of RACH preamble ramps required for Random Access Channel (RACH) transmission, received power on the downlink reference channel.

3. The method of claim 1 wherein the measurement reports are sent periodically with random offsets to reduce the likelihood of collisions between WTRUs.

4. The method of claim 1, wherein a set of signature sequences of a RACH preamble is reserved for sending the measurement report via the RACH to distinguish RACH transmissions that include the measurement report from RACH transmissions that do not include the measurement report.

5. The method of claim 1 wherein a set of channelization and scrambling codes are reserved for sending the measurement report via the RACH to distinguish RACH transmissions that include the measurement report from RACH transmissions that do not include the measurement report.