KR200396563Y1 - Apparatus for dynamically adjusting data transmission parameters and controlling h-arq processes - Google Patents

Abstract

In a wireless communication system including a wireless transmit / receive unit (WTRU) for transmitting data to a Node-B, data transmission parameters, such as modulation and coding scheme (MCS) and transport block set (TBS) size, determine the transmission time interval (TTI). The hybrid-automatic repetition request (H-ARQ) process, which is dynamically adjusted on the basis and, if necessary, used to control the data transfer between the WTRU and the Node-B, is started and released. The WTRU transmits or retransmits data to Node-B over an Extended Uplink (EU) Dedicated Channel (E-DCH) in accordance with the data feedback information received from Node-B. The WTRU queues data for transmission and determines the transmission status of the data. The transmission status is set to one of "new transmission", "successful transmission", "retransmission" and "restarted transmission". During each TTI, the WTRU initiates EU transmission to Node-B, which identifies the assigned H-ARQ process, TBS and MCS.

Description

APPARATUS FOR DYNAMICALLY ADJUSTING DATA TRANSMISSION PARAMETERS AND CONTROLLING H-ARQ PROCESSES

The present invention relates to a wireless communication system comprising a wireless transmit / receive unit (WTRU) and a Node-B. More specifically, the present invention dynamically adjusts data transmission parameters such as Modulation and Coding Scheme (MCS), and Transport Block Set (TBS) size, between WTRU and Node-B. The present invention relates to a method and apparatus for allocating and releasing a hybrid-automatic repeat request (H-ARQ) process used for data transmission control in the present invention.

In 3rd generation cellular systems, Adaptive Modulation and Coding (AM & C), and H-ARQ schemes are enhanced uplinks designed to provide lower transmission latency, higher throughput, and more efficient use of physical resources. : EU) We are studying for integration into operation.

The AM & C scheme allows the MCS to be dynamically adjusted on the basis of a Transmit Time Interval (TTI), so that the MCS is selected that uses the radio resources most efficiently and provides the highest possible data rate during each TTI. Less robust MCSs use less physical resources, but are more vulnerable to errors. More robust MCSs use more physical resources, but are more resistant to errors.

The H-ARQ scheme is used to transmit and retransmit with low latency. The main aspect of the H-ARQ scheme is that the data received from the failed transmission can be flexibly combined with the successful transmission to increase the likelihood of successful reception. Either Chase Combining (CC) or Incremental Redundancy (IR) can be used. If CC is used, the same MCS is selected for retransmission. If IR is used, a more robust MCS is used for each retransmission.

The present invention is implemented in a wireless communication system including a WTRU for transmitting data to a Node-B. Data transmission parameters, such as TBS size, are dynamically adjusted based on the TTI. Optionally, the MCS can be adjusted. The H-ARQ process used to control the data transfer between the WTRU and the Node-B is allocated and released as needed. The WTRU transmits or retransmits data to Node-B over an Extended Uplink (EU) Dedicated Channel (E-DCH) in accordance with the data feedback information received from Node-B. The WTRU queues data for transmission and determines the transmission status of the data. The transmission status is set by the controller of the WTRU to one of "new transmission", "successful transmission", "retransmission" and "restarted transmission". During each TTI, the WTRU initiates EU transmissions to Node-B that explicitly or implicitly identify the number of retransmissions, new data indications, assigned H-ARQ processes, TBS and MCS (optional).

The transmission status of the data is set by the controller of the WTRU, which is "new transmission" if the data is new data, or "successful transmission" if an ACK message is received from the Node-B. In this case, if the NACK message is received from the Node-B or if no response is received, the transmission status of the data is set to "retransmission" and, optionally, "restart transmission" if the retransmission count exceeds a predetermined maximum number of retransmissions. do.

If the transfer status is "New Transfer", the first H-ARQ process is allocated. If the transmission status is "retransmission", the same H-ARQ process is allocated while incrementing the retransmission counter. If the retransmission status is "successful transmission", the H-ARQ process is released. Optionally, if the transmission status is "restarted transmission", an H-ARQ process is allocated during the initialization of the retransmission counter and incrementing the new data indicator (NDI).

From now on, the term "WTRU" includes, but is not limited to, a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, or other type of device operable in a wireless environment. The term "node-B" includes, but is not limited to, a base station, site controller, access point or other type of interfacing device in a wireless environment.

Features of the present invention may be integrated into an integrated circuit (IC), or may consist of a circuit comprising a plurality of interconnect components.

1 is a block diagram of a wireless communication system 100 operating in accordance with the present invention. System 100 includes a WTRU 102, a Node-B 104, and a radio network controller (RNC) 106. The WTRU 102 transmits data using the transmitter 120 over the E-DCH 108 and transmits the receiver 122 over the downlink (DL) signaling channel 110 based on the disclosed H-ARQ process. Receive feedback from Node-B 104. If the Node-B 104 fails to decode the data transmitted by the WTRU 102, the Node-B 104 sends a NACK message to the WTRU 102 over the DL signaling channel 110 or It does not transmit the feedback interpreted by the WTRU 102 to the NACK. If Node-B 104 succeeds in decoding the data sent by WTRU 102, Node-B 104 sends an ACK message to WTRU 102 which releases the H-ARQ process for other transmissions. do. H-ARQ processes may be designed to implement CC or IR. The RNC 106 controls the overall operation of the data transfer that occurs between the Node-B 104 and the WTRU 102, including radio resource allocation. The WTRU 102 may include a data buffer 112 for storing E-DCH data, an optional data lifespan timer 114 used to determine whether expired data needs to be discarded, and the WTRU 102. A retransmission counter 116 is used to determine whether data transmitted by but not received by Node-B 104 should be retransmitted or whether the H-ARQ transmission should be terminated or optionally restarted. The buffer 112, lifetime timer 114, and retransmission counter 116 are controlled by the controller 118. Controller 118 sets (ie, tracks) each transmission state associated with the H-ARQ process.

2 is a flow diagram of a process 200 including method steps for controlling an H-ARQ process in accordance with the present invention. The H-ARQ process can be synchronous or asynchronous. In synchronous H-ARQ operation, the WTRU 102 tracks the time at which a response to the data transmission between the WTRU 102 and the Node-B 104 is expected, and the period of H-ARQ retransmission is predetermined. In an asynchronous H-ARQ operation, the WTRU 102 transmits data and waits for feedback for a predetermined time period.

After the WTRU 102 starts the H-ARQ process and retransmission counter 116, the WTRU 102 sends data to the Node-B 104 via the E-DCH 108 during the current TTI (step 202). . At step 204, the WTRU 102 waits for feedback from the Node-B 104. When the WTRU 102 receives an ACK message from the Node-B 104, the WTRU 102 sets the transmission status to "successful transmission", releases the H-ARQ process, and retransmits for subsequent data transmission. The counter 116 is restarted (step 208).

In step 206, if the WTRU 102 receives a NACK message or no response, the WTRU 102 determines whether the retransmission count indicated by the retransmission counter 116 is less than the maximum number of retransmissions allowed. (Step 212).

If the retransmission count determined in step 212 is less than the maximum number of retransmissions allowed, the WTRU 102 sets or maintains the transmission status to " retransmission " and increments the retransmission counter 116 (step 214). The retransmission counter 116 is incremented each time the same data is retransmitted by the WTRU 102.

If the retransmission count determined in step 212 is greater than the maximum number of retransmissions allowed, then the H-ARQ process transfer is terminated and reset to support subsequent data transfers (step 213). Optionally, the WTRU 102 may set the transmission status to "restarted transmission" and restart the retransmission counter (step 216). After setting the transmission status to "restarted transmission", WTRU 102 may restart the H-ARQ transmission process as a "new transmission" or WTRU 102 may optionally release the H-ARQ process ( Step 218).

3 is a flow diagram of a process 300 including method steps for implementing a CC in accordance with the present invention. Process 300 is performed on a TTI basis (step 302). In step 304, the WTRU 102 determines whether EU physical resources have been allocated by the Node-B 104 and the WTRU 102 sends data to the Node-B 104 via the E-DCH 108. Determine if the ARQ process is available. If EU physical resources are not allocated, the WTRU 102 waits for the allocation of EU physical resources, and the transmission of data is delayed until the next TTI (step 302). If EU physical resources have been allocated and the H-ARQ process is available, the WTRU 102 determines whether the data is new data (step 306). If the data is determined to be new data in step 306, the WTRU 102 selects the highest priority data to send (step 308). In addition, the WTRU 102 selects an MCS and TBS size that maximizes transmission of highest priority data within acceptable limits. The TBS size is selected based on the signaled maximum MCS and TBS size of Node-B 104, the transmit power available for E-DCH 108, the MCS, and the data available in buffer 112 for transmission.

For each Transport Channel (TrCH), the Dedicated Channel Medium Access Control (MAC-d) flow or logical channel of the Dedicated Channel, a list of allowed TBS sizes, retransmission limits and allowable transmission latency ( That is, "lifetime" of the MAC data is determined. The allowable MCS and TBS sizes are the maximum values that the WTRU 102 is allowed to transmit during the allocation period of current physical resources. The configuration is signaled from the RNC 106 in accordance with a Radio Resource Control (RRC) procedure or uniquely specified by a standard. The selected MCS and TBS sizes are either explicitly signaled (preferably from Node-B) or associated parameters such as Channel Quality Indicator (CQI) and / or Transport Format Combination (TFC) indexes. Can be obtained from CQI may indicate the maximum allowed WTRU interference or transmit power. Node-B 104 may signal this information in the initial channel assignment. Alternatively, Node-B 104 may transmit this information when WTRU 102 requests additional EU channel allocation.

In step 312, the WTRU 102 generates one or more EU MAC (MAC-e) protocol data units (PDUs) based on the selected TBS size and assigns an H-ARQ process for the transmission of the MAC-e PDU. In step 314, the WTRU 102 starts the retransmission counter 116, increments the NDI, and optionally sets the life timer 114 of the WTRU 102. NDI is used to indicate when new data is being transmitted or when Node-B 104 needs to clear the soft buffer associated with the H-ARQ process being transmitted. The initial value of the retransmission counter 116 may be interpreted as the transmission of new data, in which case NDI parameters are not needed. Thereafter, the WTRU 102 initiates EU transmission to Node-B 104 identifying the current H-ARQ process, TBS size, (if not allocated by Node-B 104) and MCS. The specific H-ARQ process operation allows the Node-B 104 to be aware of the H-ARQ process and the MCS clearly, so that the WTRU 102 does not need to signal to the Node-B 104.

If CC is supported, TBS size information is identified at Node-B 104 for each transmission or retransmission, unless the TBS is identified by Node-B 104 in the physical channel assignment. The retransmission has the same MCS and TBS as applied to the initial transmission in the case of CC.

Referring back to step 306, if it is determined that the data is not new data, it is determined whether the WTRU 102 uses the life timer 114 (step 315). If the WTRU 102 uses the lifetime timer 114, the process 300 proceeds to step 316 to determine whether the lifetime timer 114 has expired. If the life timer 114 has expired, the WTRU 102 discards the data and releases the H-ARQ process (step 318), and the process 300 returns to step 302. Optionally, if lifespan timer 114 is nearing expiration, WTRU 102 may use a more robust MCS to increase the likelihood of successful transmission.

The retransmission counter 116 of the WTRU 102 is incremented each time data is not successfully transmitted and therefore not recognized by the Node-B 104. If the lifetime timer 114 has not yet expired or if the WTRU 102 does not use the lifetime timer 114, the process 300 proceeds to step 320 for data transmission and the WTRU 102 It is determined whether the retransmission count is less than the maximum number of retransmissions allowed. If the retransmission count is less than the maximum number of retransmissions allowed, then the status of the transmission is set or maintained as "retransmission", and the WTRU 102 increments the retransmission count 116 (step 322), the same H-ARQ process, TBS, MCS and NDI (if not integrated into the retransmission counter) are used (step 324). Thereafter, the WTRU 102 may perform an H-ARQ process (which is clearly recognized by Node-B and does not need to be signaled), TBS size (if not allocated by Node-B), and associated physical control channels. Start EU transfer to Node-B 104 identifying the MCS (step 330).

If the retransmission count is more than the maximum number of retransmissions allowed, process 300 proceeds to step 318 where it discards the data and releases the H-ARQ process. Alternatively, if it is determined in the optional step 325 that the restarted transmission is allowed, then the restarted transmission is set to "restarted transmission" and the WTRU 102 starts the retransmission counter 116 and increments the NDI. And assign a new H-ARQ process (step 326). If previously transmitted data stored in the soft combining buffer disrupts successful retransmission, it is better to clear the soft buffer and restart the H-ARQ transmission to increase the probability of successful transmission. Thus, when the maximum number of retransmissions is reached for a particular H-ARQ process, an NDI (or an initialized retransmission count) is transmitted indicating that the H-ARQ transmission has been restarted. When Node-B 104 receives an incremental NDI (or transmit count set to an initial value), Node-B 104 clears the soft combination buffer of previously received data.

In step 328, a new H-ARQ transmission is started using the same TBS, and optionally a more robust MCS may be selected for the "new transmission" to increase the likelihood of successful transmission (step 328). To allow for this change in the MCS, the TBS can be split into several independent transmissions. If the transmission is restarting with more redundancy (either due to changes in MCS or less puncturing), the old TBS will no longer be suitable for the allocated physical resource. In this case, the original transmission may be divided into multiple separate transmissions that do not exceed the requirements. Thereafter, the WTRU 102 identifies the current H-ARQ process (obviously known to node-B), the MCS (if not assigned by node-B) and the TBS size in the associated physical control channel. Start EU transmission to the network (step 330).

4 is a flow diagram of a process 400 including method steps for implementing an IR in accordance with the present invention. Process 400 is performed on a TTI basis (step 402). In step 404, the WTRU 102 determines whether EU physical resources have been allocated by the Node-B 104 and the WTRU 102 sends data to the Node-B 104 via the E-DCH 108. -Determine whether the ARQ process is available (step 404). If EU physical resources are not allocated, the WTRU 102 waits for the allocation of EU physical resources, and the transmission of data is delayed until the next TTI (step 402). If EU physical resources have been allocated and H-ARQ is available, the WTRU 102 determines whether the data is new data (step 406). If it is determined in step 406 that the data is new data, the WTRU 102 selects the highest priority data to send (step 408). In addition, the WTRU 102 selects the corresponding TFC that maximizes the transmission of the maximum TBS size and highest priority data using the most robust MCS allowed (step 410).

In step 412, the WTRU 102 generates one or more MAC-e PDUs based on the selected TBS size and assigns an H-ARQ process for the transmission of the MAC-e PDU. In step 414, the WTRU 102 initializes the retransmission counter 116, increments the NDI, and optionally sets the life timer 114 of the WTRU 102 (step 414). NDI is used to indicate when new data is being transmitted or when Node-B 104 needs to clear the soft buffer associated with the H-ARQ process being transmitted. The initial value of the retransmission counter 116 may be interpreted as the transmission of new data, in which case NDI parameters are not needed. Thereafter, the WTRU 102 begins EU transmission to Node-B 104 identifying the current H-ARQ process, MCS and TBS size in the associated physical control channel (step 430). The H-ARQ process and the MCS can be clearly recognized by the Node-B 104 due to certain H-ARQ process operations, so that the WTRU 102 does not need to signal to the Node-B 104.

Referring back to step 406, if it is determined that the data is not new data, it is determined whether the WTRU 102 uses the life timer 114 (step 415). If the WTRU 102 uses the lifetime timer 114, the process 400 proceeds to step 416 and determines whether the lifetime timer 114 has expired. If the lifetime timer 114 has expired, the WTRU 102 discards the data, releases the H-ARQ process (step 418), and the process 400 returns to step 402. Optionally, if lifespan timer 114 approaches expiration, WTRU 102 may use a more robust MCS to increase the likelihood of successful transmission.

The retransmission counter 116 of the WTRU 102 is incremented whenever it is not recognized by the Node-B 104 because the data transfer was not successful. If the lifetime timer 114 has not yet expired or if the WTRU 102 does not use the lifetime timer 114, the process 400 proceeds to step 420 for retransmission of the data and the WTRU 102. Determines whether the retransmission count is less than the maximum number of retransmissions allowed. If the retransmission count is less than the maximum number of retransmissions allowed, the status of the transmission is set or maintained to " retransmission " if allowed, and the WTRU 102 increments the retransmission counter 116 and further increases the robust MCS. Choose. In step 424 the WTRU 102 uses the same H-ARQ process, TBS / TFC and NDI.

For IR, the determination of the MCS and TBS sizes takes into account the support of the most robust MCS, what data is scheduled for transmission in the WTRU 102, and the available WTRU transmit power. With each retransmission, a more robust MCS can be selected for the same TBS. Initial transmission with less robust MCS is allowed for larger TBS size, but this size is limited so that the same TBS can still be supported by the most robust MCS. In addition, for the determination of the TBS, even if the most robust MCS is not required for successful transmission, the maximum robust MCS that the WTRU can use for the EU should be considered.

If the retransmission count is greater than or equal to the maximum value, process 400 proceeds to step 418 to discard the data and release the H-ARQ process. Alternatively, if it is determined in step 425 that the restarted transmission is allowed, then the transmission status is set to "restarted transmission", the WTRU 102 initializes the retransmission counter 116, increments the NDI, and Allocate an H-ARQ process (step 426). In step 428, the same TBS / TFC is used and the MCS is selected.

While the features and elements of the present invention have been described as preferred embodiments in certain combinations, each feature or element may be used alone or with other features and elements of the present invention, or without the other features and elements of the preferred embodiments, or It can be used in various combinations that do not have.

Although the present invention has been described as a preferred embodiment, it will be apparent to those skilled in the art that other variations, such as those set forth in the appended claims, are included in the scope of the present invention.

According to the present invention, it dynamically adjusts data transmission parameters such as modulation and coding scheme (MCS), and transport block set (TBS) size, and transmits data between WTRU and Node-B. A hybrid-automatic repeat request (H-ARQ) process used for control can be allocated and deallocated.

With the following drawings, the present invention will be understood in more detail from the preferred embodiments described below by way of example.

1 is a block diagram of a wireless communication system operating in accordance with the present invention.

2 is a flowchart of a process for initiating and releasing an H-ARQ process according to the present invention.

3 is a flow diagram of a process including steps of a method for implementing a CC in accordance with the present invention.

4 is a flow diagram of a process including steps of a method for implementing an IR in accordance with the present invention.

Claims (15)

A wireless transmit / receive unit (WTRU) for dynamically adjusting data transmission parameters to transmit Extended Dedicated Channel (E-DCH) data to Node-B, A buffer for queuing E-DCH data; A retransmission counter for tracking the number of transmissions of the same data block; A transmitter and a receiver for transmitting and receiving the E-DCH data; And A controller electrically coupled to the buffer, the retransmission counter, the transmitter and the receiver, the controller selects data and transmission parameters for the transmission of the E-DCH data to the Node-B, and determines the transmission of the data. Allocating a hybrid automatic repeat request (H-ARQ) process for And when the data is new data, the controller selects a data transmission parameter within an allowable limit and initializes a retransmission count. The wireless transmit / receive unit according to claim 1, wherein the data transmission parameter is a modulation and coding scheme. 2. The WTRU of claim 1 wherein the data transmission parameter is a transport block set size. The method of claim 2, If the selected data for transmission is not new data, the controller determines whether the retransmission count of the selected data is less than the maximum number of transmissions allowed, and if the retransmission count is less than the maximum value, the controller And retransmitting data incrementing the retransmission count. 5. The WTRU of claim 4 wherein the same transmission parameter is used for the retransmission. 5. The WTRU of claim 4 wherein a more robust defense and coding scheme is used for the retransmission. 4. The WTRU of claim 3 wherein the transport block is divided into one or more transport blocks. 5. The WTRU of claim 4 wherein if the retransmission count is not less than the maximum, the data is discarded and the associated H-ARQ process is released. 5. The WTRU of claim 4 wherein if the retransmission count is not less than the maximum value, the controller restarts the H-ARQ process transmission while initializing the retransmission count. 10. The WTRU of claim 9 wherein a new data indicator is transmitted indicating restart of the retransmission. 10. The WTRU of claim 9 wherein the same data transmission parameters are used for the restarted transmission. 10. The WTRU of claim 9 wherein a more robust modulation and coding scheme is used for the restarted transmission. The method of claim 1, Further comprising a life timer for tracking the life span of the data, And the controller discards the data when the life timer expires. An integrated circuit (IC) for dynamically adjusting data transmission parameters to transmit Extended Dedicated Channel (E-DCH) data to a Node-B, A buffer for queuing E-DCH data; A retransmission counter for tracking the number of transmissions of the same data block; A transmitter and a receiver for transmitting and receiving the E-DCH data; And A controller electrically coupled to the buffer, the retransmission counter, the transmitter and the receiver, the controller selects data and transmission parameters for the transmission of the E-DCH data to the Node-B, and determines the transmission of the data. Allocating a hybrid automatic repeat request (H-ARQ) process for If the data is new data, the controller selects a data transmission parameter within an acceptable limit and initializes a retransmission count. 15. The integrated circuit (IC) of claim 14 wherein the integrated circuit (IC) is located in a wireless transmit / receive unit (WTRU).