Method and apparatus for dynamically adjusting data transmission parameters and controlling h-arq processes

Method and device for dynamically adjusting data transmission parameters and controlling H-ARQ program

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

The present invention relates to a wireless communication system including a wireless transmission/reception unit (WTRU) and a Node B. The present invention particularly relates to a method and device for dynamically adjusting data transmission parameters, such as modulation and coding mechanism (MCS) and The transmission block set (TBS) size, and the allocation and release are used to control the automatic repeat request (H-ARQ) procedure between the WTRU and the Node B.

In the third-generation cellular system, adaptive modulation and coding (AM&C) and H-ARQ mechanisms have been studied for integration into enhanced uplink (EU) operations, which are designed to provide low transmission latency , Higher productivity, and more efficient use of physical resources.

The AM&C mechanism allows the MCS to be dynamically adjusted on the basis of the Transmission Time Interval (TTI), so that for each TTI, the MCS is selected so that the radio resources can be used more effectively and provide the highest possible data rate. A less robust MCS will use less physical resources, but will be more prone to errors. A more robust MCS uses more physical resources, but provides more protection against errors.

The H-ARQ mechanism is used to generate transmission and retransmission with lower latency The main direction of the H-ARQ mechanism is that the data received in the failed transmission can be softly combined with the retransmission of the connection to increase the probability of successful reception. Chase Combining (CC) or increased redundancy can also be used. (incremental resunsancy, IR). When using CC, the same MCS will be used for retransmission. When using IR, a more robust MCS will be used for each retransmission.

The present invention is implemented in a wireless communication system, which includes a WTRU transmitting data to a node B. The data transmission parameters similar to the size of the TBS are dynamically adjusted on the basis of the TTI, and optionally, the MCS can also be adjusted. The H-ARQ procedure used to control the data transmission between the WTRU and the Node B depends on the dispatch and release required. The WTRU transmits and retransmits data to the Node B via the Enhanced Uplink (EU) Dedicated Channel (E-DCH), which is based on receiving feedback information from the Node B. The WTRU stores the transmission data in the queue and determines the transmission status of the data. The transmission status is set by the controller in the WTRU to "new transmission", "successful transmission", "retransmission" and "restart transmission" ". During each TTI, the WTRU initiates EU transmission to the Node B, which explicitly or implicitly identifies the number of retransmissions, new data instructions, allocation of H-ARQ procedures, TBS size, and optionally MCS.

When the data is new, the data transmission status will be set to "new transmission" by the controller in the WTRU. When receiving an acknowledgment (ACK) message from the node B, it is set to "successful transmission". When both receive a non-acknowledgement (NACK) message from node B, or do not receive a response from the node B in response to new data transmission, it is set to "retransmission". When the retransmission count exceeds the preset maximum retransmission, it is selectively set to "restart transmission".

If the transmission status is "new transmission", it will be assigned to start the H-ARQ procedure. If the transmission status is "retransmission", the same H-ARQ procedure is assigned, and the retransmission counter is incremented. If the transmission status is "successful transmission", the H-ARQ procedure is released. If the transmission status is "restart transmission", which is optional, the H-ARQ procedure will be dispatched, the retransmission counter will be started at the same time, and the new data indicator (NDI) will be incremented.

<p>100Wireless communication system</p><p>WTRUWireless Transmission/Receiving Unit</p><p>E-DCHDedicated Channel</p><p>RNCWireless Network Controller</p>

Figure 1 shows a block diagram of a wireless communication system operating according to the present invention; Figure 2 shows a flow chart of the start and release of the H-ARQ program according to the present invention; Figure 3 shows the process including execution according to the present invention The flowchart of the procedure of the CC method; and Figure 4 shows the procedure of the procedure including the steps of the IR method according to the present invention.

Hereafter, the term "WTRU" includes but is not limited to user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, or any type of device that can operate in a wireless environment. When this article refers to the dedicated term "Node B" hereinafter, it includes but is not limited to base stations, site controllers, access points, or any type of interface device in a wireless environment.

The features of the present invention can be integrated into an integrated circuit (IC) or configured on a circuit containing many interconnected components.

FIG. 1 shows a block diagram of a wireless communication system 100 according to the present invention. The system 100 includes a WTRU 102, a Node B 104, and a radio network controller (RNC) 106. The WTRU 102 transmits data via the transmitter 120 via the E-DCH 108, and transmits the channel 110 via a downlink (DL) signal to the receiver 122 to receive feedback from the Node B 104, which is based on the initial H-ARQ procedure. When the Node B cannot decode the data sent by the WTRU 102, the Node B will transmit a NACK message to the WTRU 102 via the DL signal transmission channel 110, or if it does not transmit, the WTRU 102 will interpret it as a NACK feedback. When the Node B successfully decodes the data sent by the WTRU 102, the Node B 104 will transmit an ACK message to the WTRU 102, which will release the H-ARQ procedure to other transmissions. The H-ARQ procedure can be designed to execute CC or IR. The RNC 106 controls the overall operation of data transmission that occurs between the Node B 104 and the WTRU 102, including radio resource allocation. The WTRU 102 includes a data buffer 112 for storing E-DCH data, an optional data lifetime timer 114 for determining whether to discard expired data, and a retransmission counter 116 for determining whether the WTRU 102 Transmitted but not by the node B 104 Whether the received data is to be retransmitted, or whether the H-ARQ transmission should be terminated or restarted selectively. The buffer 112, the lifetime timer 114, and the retransmission counter 116 are controlled by the controller 118, which sets (ie records) each transmission status of the H-ARQ program.

Figure 2 shows a flowchart of a procedure 200 including method steps for controlling an H-ARQ procedure according to the present invention. The H-ARQ procedure can be synchronous or asynchronous. In the synchronous H-ARQ operation, the WTRU 102 records the expected response time for data transmission between the WTRU 102 and the Node B 104, and the predetermined H-ARQ retransmission period. In an asynchronous H-ARQ operation, the WTRU 102 transmits data and waits for feedback within a preset time.

After the WTRU 102 starts the H-ARQ procedure and the retransmission counter 116, the WTRU 102 transmits data to the Node B 104 via the E-DCH 108 during the current TTI (step 202). In step 204, the WTRU 102 waits for feedback from the Node B 104, if When the WTRU 102 receives the ACK message from the Node B 104, the WTRU 102 then sets the transmission status to "successful transmission", releases the H-ARQ procedure, and restarts the retransmission counter 116 for subsequent data transmission (Step 208).

In step 206, if the WTRU 102 receives a NACK message or does not receive any response, the WTRU 102 determines whether the retransmission count indicated by the retransmission counter 116 is less than or equal to the maximum allowed retransmission Value (step 212).

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

If the retransmission count determined in step 212 is equal to or greater than the maximum allowable retransmission, the H-ARQ procedure transmission will be terminated, and the configuration will be reset to support subsequent data transmission (step 213). Optionally, the WTRU 102 can set the transmission status to "restart transmission" and restart the retransmission counter (step 216). After setting the transmission status to "restart transmission", the WTRU 102 will start the H-ARQ transmission procedure as "new transmission", or the WTRU 102 may selectively release the H-ARQ procedure (step 218 ).

Figure 3 shows a flowchart of a procedure 300 including steps for executing the CC method according to the present invention. The procedure 300 is executed 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 whether the H-ARQ procedure is available for the WTRU 102 to transmit data to the Node B 104 via the E-DCH 108. If the EU physical resources have not been allocated, the WTRU 102 waits for the configuration of the EU physical resources and the data transmission will be delayed to the next TTI (step 302). If EU physical resources have been configured and H-ARQ is available Procedure, 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 for transmission (step 308). In addition, the WTRU 102 selects the MCS and TBS sizes that can maximize the highest priority data transmission within the permission limit (step 310). The selection of the TBS size is based on the maximum MCS sent by the Node B 104, the TBS size, the transmission power available for the E-DCH 108, the MCS, and the data available for transmission in the buffer 112.

For each transmission channel (TrCH), dedicated channel media access control (MAC-d) flow or logical channel, the allowable TBS size, retransmission limit, and allowable transmission waiting time (that is, the MAC data "use period" "), the allowable MCS and TBS sizes are the maximum amounts that the WTRU 102 is allowed to transmit in the current physical resource configuration period transmission. These configurations are sent by the RNC 106 according to the radio resource control procedure, or specified by the standard describe. The selected MCS and TBS sizes can be explicitly sent (preferably from Node B) or obtained from related parameters, such as channel quality indicator (CQI) and/or transport format combination (TFC) index. The CQI can be Indicates the maximum allowable WTRU interference or transmission power. The Node B 104 may send this signal in the initial channel allocation, or the Node B 104 may send this information when the WTRU 102 requests additional EU channel allocation.

In step 312, the WTRU 102 then generates at least one EU MAC (MAC-e) protocol data unit (PDU) based on the selected TBS size, and allocates an H-ARQ procedure for the MAC-e PDU transmission. In step 314, the WTRU 102 starts the retransmission counter 116, increments NDI, and optionally sets the lifetime timer 114 in the WTRU 102. The NDI is used to indicate when new data is transmitted, and when the Node B needs to clear the soft buffer of the transmitted H-ARQ program. The start value of the retransmission counter 116 can be interpreted as the transmission of new data, and in this example, NDI parameters are required everywhere. The WTRU 102 then starts The initial EU is transmitted to Node B to identify the current H-ARQ procedure, TBS size (if not assigned by Node B 104), and MCS. Since the specific H-ARQ procedure operates, the H-ARQ procedure and MCS can be clearly known by the Node B 104, and therefore may not need to be sent by the WTRU 102 to the Node B 104.

When CC is supported, the TBS size information is recognized by the Node B 104 for every transmission and retransmission, unless the TBS is recognized by the Node B 104 when the physical channel is allocated. In the CC example, the retransmission has the same MCS and TBS used for the initial transmission.

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

The retransmission counter 116 in the WTRU 102 is incremented every time data is not successfully transmitted and therefore not confirmed by the Node B 104. If the lifetime timer 114 has not expired, or if the WTRU 102 does not use the lifetime timer 114, the procedure 300 proceeds to step 320 to retransmit the data, whereby the WTRU 102 determines whether the retransmission count is less than The maximum allowable retransmission. If the retransmission count is less than the maximum allowed retransmission, the transmission state will be set or maintained at "retransmission", the WTRU 102 increments the retransmission counter 116 (step 322), and uses the same H-ARQ procedure, TBS , MCS and NDI (if not integrated into the retransmission counter) (step 324). The WTRU 102 then initiates EU transmission Input to the Node B 104 to identify the H-ARQ program (which may be clearly known by the Node B and does not need to be sent to the Node B), the TBS size (if not assigned by the Node B), and the control channel of the relevant entity MCS (step 330).

If the retransmission count reaches or exceeds the maximum allowable retransmission, the procedure 300 will proceed to step 318 to discard the data and release the H-ARQ procedure. Or if the decision to restart transmission is allowed in optional step 325, the transmission status will be set to "restart transmission", and the WTRU 102 will start the retransmission counter 116, increment the NDI, and assign a new H -ARQ procedure (step 326). If the transmission data previously stored in the soft combination buffer is interrupted and retransmitted, it is better to clear the soft buffer and restart the H-ARQ transmission in order to increase the probability of successful transmission. Therefore, when the maximum number of retransmissions for a specific H-ARQ program is reached, the NDI (or the start retransmission count) will be sent to indicate that the H-ARQ transmission has been restarted. When the node B 104 receives the incremental NDI (or the transmission count is set to the start value), the node B 104 clears the soft combination buffer of the previously received data.

In step 328, a new H-ARQ transmission using the same TBS is started, and a more robust MCS can be optionally selected for the "new transmission" to increase the probability of successful delivery (step 328). In order to allow MCS changes, the TBS can be segmented into several independent transmissions. In this example, the transmissions will restart with more redundancy (whether the MCS changes or use fewer bits). The TBS may no longer meet the allocated physical resources, in this case the original transmission can be segmented into several separate transmissions, which will not exceed the demand. The WTRU 102 then initiates EU transmission to the Node B, which identifies the current H-ARQ procedure (which can be clearly known by the Node B) regarding the entity's control channel, the TBS size, and the MCS (if not by the Node B) Assign) (step 330).

Figure 4 shows the flow of a program 400 according to the present invention including the steps of executing the IR method. The program 400 is executed on the basis of TTI (step 402). In step 404, the WTRU 102 determines whether EU physical resources have been allocated by the Node B 104 and whether H-ARQ is available for the WTRU to transmit data to the Node B 104 via the E-DCH 108 (step 404). If the EU physical resources have not been allocated, the WTRU 102 waits for the allocation of the EU physical resources, and the data transmission is delayed until the next TTI (step 402). If the EU physical resources have been allocated and H-ARQ procedures are available, the WTRU 102 will determine whether the data is new (step 406). If the data is determined to be new in step 406, the WTRU 102 selects the highest priority data transmission (step 408). In addition, the WTRU 102 selects the largest TBS size and the corresponding TFC to maximize the transmission of the highest priority data, which uses the most robust MCS allowed (step 410).

In step 412, the WTRU 102 then generates at least one MAC-e PDU based on the selected TBS size, and assigns the H-ARQ procedure to the transmission of the MAC-e PDU. In step 414, the WTRU 102 starts the retransmission counter 116, increments the NDI, and optionally sets the lifetime timer 114 in the WTRU 102 (step 414). The NDI is used to indicate the time when the new data is transmitted and the Node B 104 needs to clear the soft buffer about the transmitted H-ARQ program. The start value of the retransmission counter 116 can be regarded as the transmission of new data. In this example, the NDI parameter is not required. The WTRU 102 then initiates EU transmission to the Node B 104 to identify the current H-ARQ procedure, TBS size, and MCS in the relevant entity control channel (step 430). Due to the operation of the specific H-ARQ procedure, the H-ARQ procedure and MCS can be clearly known by the Node B 104, and therefore there is no need to be sent by the WTRU 102 to the Node B 104.

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

The retransmission counter 116 in the WTRU 102 is incremented every time data is not successfully transmitted and therefore not confirmed by the Node B 104. If the lifetime timer 114 has not expired, or if the WTRU 102 does not use the lifetime timer 114, the procedure 400 proceeds to step 420 to retransmit the data, whereby the WTRU 102 determines whether the retransmission count is less than The maximum allowable retransmission. If the retransmission count is less than the maximum allowed retransmission, the transmission state will be set or maintained at "retransmission", the WTRU 102 increments the retransmission counter 116, and if permitted, selects a more robust MCS (step 422) In step 424, the WTRU 102 uses the same H-ARQ procedure, TBS/TFC, and NDI.

In terms of IR, the decision of MCS and TBS size needs to consider the support of the most robust MCS, what is the data requirement, which one is waiting for transmission in the WTRU 102, and the available WTRU transmission power. At each retransmission, a more robust MCS may be selected for the same TBS. The initial transmission of a less robust MCS may allow a larger TBS size, but this size will be limited so that the same TBS can still be supported by a more robust MCS. Similarly, in terms of TBS decision, the EU available transmission power of the WTRU must consider the soundest MCS that can be allowed, even if the soundest MCS is not required for successful transmission

If the retransmission count reaches or exceeds the maximum allowable retransmission, the procedure 400 proceeds to step 418 to discard the data and release the H-ARQ procedure. Or if in If the decision to restart transmission is allowed in step 425, the transmission status will be set to "restart transmission", and the WTRU 102 will start the retransmission counter 116, increment the NDI, and dispatch a new H-ARQ procedure (step 426 ). In step 428, use the same TBS/TFC and select MCS.

Although the features and elements of the present invention are all described in specific combinations in the embodiments, each feature or element in the embodiments can be used alone, without being combined with other features or elements, and can also be combined with/without the present invention. Other features and components are combined in different ways.

Although the present invention has been described by the preferred embodiments, other variations that do not depart from the scope of the patent application of the present invention are obvious to those skilled in the art.