HK1100597B - Method and apparatus for implementing a data lifespan timer for enhanced dedicated channel transmissions - Google Patents

Description

Method and apparatus for implementing enhanced dedicated channel transmission data usage period timer

Technical Field

The present invention relates to a wireless communication system, which includes at least one wireless transmit/receive unit (WTRU), at least one node-B and a Radio Network Controller (RNC). More particularly, the present invention relates to a method and apparatus for implementing a data usage period timer that supports enhanced dedicated channel (E-DCH) transmissions.

Background

Methods for improving Uplink (UL) coverage, throughput, and transmission latency are currently being investigated in the third generation partnership project (3GPP) release 6 (R6). To achieve these goals, the node B takes over the responsibility of scheduling and assigning uplink resources to WTRUs, the node B can make more efficient decisions and manage short-range based radio resources better than the RNC, which still maintains general overall control over the cells with Enhanced Uplink (EU) so that the RNC can perform functions like call admission control and congestion control.

Hybrid automatic repeat request (H-ARQ) techniques provide a procedure to generate transmissions and retransmissions with low latency. One major direction in H-ARQ techniques is that the data received in the event of a failed transmission is smoothly combined with successive retransmissions in order to increase the probability of successful reception.

When using the H-ARQ mechanism and node B scheduling for transmission, the time required for successful transmission of data varies, and significantly delaying transmission adversely affects the transmission applications that require only very low latency, e.g., delayed data may be treated as a failed transmission and the application may end up with unnecessary retransmissions, thus requiring a mechanism to limit transmission latency.

Disclosure of Invention

The present invention is implemented in a wireless communication system supporting E-DCH data transmission, the wireless communication system comprising a wireless transmit/receive unit (WTRU), at least one node-B, and a Radio Network Controller (RNC). The WTRU includes a data buffer, a data lifespan timer, a data retransmission counter, a hybrid automatic repeat request (H-ARQ) process, and a controller. The data lifespan timer establishing a lifespan for at least one data block stored in the buffer, the WTRU configured to (i) periodically determine whether the lifespan timer has expired; (ii) determining whether the data block was previously transmitted; (iii) determining whether the lifespan timer is about to expire; and (iv) determining whether the entity resource has been configured. The WTRU sends an emergency channel allocation request to the node-B if physical resources are not allocated to the data block whose lifespan timer is about to expire, and prioritizes transmission of the data block relative to other data blocks if physical resources are allocated. The data block is discarded if the lifespan timer expires or if the WTRU receives feedback information indicating that the data block was not successfully received by the node-B.

Drawings

The invention will be understood in more detail from the following description of a preferred embodiment, given as an example, with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of the operation of a wireless communication system in accordance with the present invention; and

figure 2 is a flowchart of a process for implementing a data lifespan timer in a WTRU of the system of figure 1 in accordance with the present invention.

Detailed Description

The term "WTRU" as used herein includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, the terminology "node B" includes but is not limited to a base station, a site controller, an access point, or any other interfacing device in a wireless environment.

The features of the present invention may be integrated into an Integrated Circuit (IC) or may be configured on a circuit comprising a plurality of interconnected components.

Figure 1 is a block diagram of a wireless communication system 100 according to the present invention, the system 100 including at least one WTRU102, at least one node-B104 and at least one RNC 106. The WTRU102 includes a controller 122, a data lifespan timer 124, a buffer 126, and H-ARQ processes 128, optionally with a retransmission counter 130. The controller 122 controls the overall data transmission steps including the initial data lifespan timer 124 and the configuration of an H-ARQ process 128.

The RNC 106 controls the overall EU operation of the system 100 by configuring the node-bs 104 and the WU parameters of the WTRU102, such as the age of the transport channels (TrCH) or logical channel data, the initial transmit power level, the maximum allowed EU transmit power, or the available channel resources per node-B104, and the E-DCH is established to support EU transmissions between the WTRU102 and the node-bs 104.

Regarding the E-DCH transmission, the WTRU102 sends a channel allocation request to the node-B104 via an UL EU signaling channel 110, which channel allocation request (or other UL EU signaling) may be transmitted via the E-DCH108 instead of the UL EU signaling channel 110, and in response, the node-B104 sends channel allocation request information to the WTRU102 via a Downlink (DL) EU signaling channel 112, after EU radio resource allocation to the WTRU102, the WTRU102 transmits data via an E-DCH 108. In response to the E-DCH data transmission, the node-B104 sends an Acknowledgement (ACK) or non-acknowledgement (NACK) message of an H-ARQ operation via the DL EU signaling channel 112.

Figure 2 is a flow diagram of a process 200 for implementing a data lifespan timer 124 in a WTRU102 for supporting E-DCH transmissions in accordance with the present invention. The WTRU102 may use multiple data lifespan timers 124 to process multiple E-DCH transmissions simultaneously.

After a new data block transmitted via the E-DCH108 is received, the controller 122 starts a data lifespan timer 124 of the data block and combines an H-ARQ process 128 with the data block, and the new data block waits in the buffer 126 (step 202). The RNC configures the data lifetime for each E-DCH TrCH or each E-DCH logical channel, initializing the timer for each transmission based on whether the UL transmission is received at the MAC or RLC.

The value of the E-DCH data lifespan timer 124 may be determined by the controller 122 of the WTRU102 considering several factors such as maximum allowed transmission latency, RLC configuration, the TrCH block error rate (BLER), etc., for example, which determines how long the data may stay in a buffer before transmission. In addition, the BLER determines the number of H-ARQ retransmissions, which affects transmission latency. The value assigned to the data lifespan timer 124 may also allow for WTRU data processing, which is processed externally at the EU medium access control entity (MAC-e) of the WTRU 102.

Application communication protocols (e.g., TCP/IP) require minimal transmission latency and minimal changes in transmission latency in order to achieve maximum productivity. When transmission delays occur, data is expected to fail or be discarded rather than being delayed and retransmitted, resulting in inefficient behavior of the application.

For each TTI, the controller 122 determines whether the data lifespan timer 124 for the data block has expired in the buffer 126 of the WTRU102 (step 206). If the data lifespan timer 124 has expired, the controller 122 discards the data block and releases the associated H-ARQ process 128 (step 208), the WTRU102 may report this event to the RNC 106 or node-B104 (step 210), the WTRU102 may further report to the node-B104 by sending a channel allocation request with a specific indication that the physical resource allocation is insufficient.

Returning to step 206, if the data lifespan timer 124 for the data block has not expired, the controller 122 determines whether a data block in the buffer 126 of the WTRU102 has been previously transmitted by the WTRU102 (step 212), further determines whether data feedback information associated with the data block has been received by the node-B if the data block has been previously transmitted (step 214), removes the data block from the buffer 126 if an Acknowledgement (ACK) indicates that the data block was successfully transmitted, and the associated H-ARQ process 128 is freed to support other data blocks, and the data lifespan timer is reset (step 216), and if no feedback information is received, the WTRU102 waits for the feedback information until the next TTI (step 218).

If it is determined that the data block was not previously transmitted by the WTRU102 or that the data block was transmitted but a non-acknowledgement message (NACK) was received indicating that the transmission of the data block failed, the data block is retransmitted at step 212. The controller 122 determines whether the data lifespan timer for the data block has neared expiration, and if the data lifespan timer 124 has not neared expiration, a standard H-ARQ operation is initiated to transmit the data block (step 222).

When the data lifespan timer 124 nears expiration, at step 224, the controller 122 determines whether physical resources have been allocated (step 224), if physical resources have been allocated, the controller 122 may selectively prioritize transmission of the data block (step 226), and if physical resources have not been allocated, the controller 122 may selectively send an emergency channel allocation request to the node B to support transmission of the data block (step 228).

Returning to step 214, if a NACK is not received, the data block is retransmitted, the controller 122 determines whether the retransmission counter 130 has reached a maximum retransmission limit (step 230), the retransmission counter 130 is incremented each time the data block is retransmitted, and the maximum retransmission limit is set by the RNC. If the retransmission counter 130 has not reached the maximum retransmission limit, the process 200 proceeds to step 220. if the retransmission counter 130 has reached the maximum transmission limit, the controller 122 reinitiates the H-ARQ process 128 (step 232) as long as the data lifespan timer 124 for the data block has not expired, the retransmission counter 130 is initialized and a new data indicator is incremented to indicate the H-ARQ process 128 is reinitialized.

Although the features and elements of the present invention are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements of the present invention.

Claims (14)

1. In a wireless communication system including a wireless transmit/receive unit (WTRU) and at least one node-B, a method for utilizing at least one data lifespan timer in the WTRU to support enhanced dedicated channel (E-DCH) data transmissions, the method comprising:

receiving an E-DCH data block to be transmitted from a higher layer;

storing the E-DCH data block to be transmitted in a buffer of the WTRU;

starting a data lifetime timer of the E-DCH data block;

assigning the E-DCH data block to a hybrid automatic repeat request H-ARQ process;

if the data lifespan timer is close to expiring, determining whether physical resources have been allocated for transmission of the E-DCH data block;

if the physical resource has not been allocated, sending an emergency channel allocation request to the node B, and if the physical resource has been allocated, giving transmission priority to the E-DCH data block; and

when the data lifespan timer expires, the E-DCH data block is discarded and the H-ARQ process is released.

2. The method of claim 1, further comprising:

if the data block has been previously transmitted and the data lifespan timer has not nearly expired, a standard H-ARQ operation is initiated for transmission of the data block.

3. The method of claim 1, wherein the data lifespan timer is configured for each of a plurality of transport channels TrCHs.

4. The method of claim 1, wherein the data lifespan timer is configured for each of a plurality of logical channels.

5. The method of claim 1 wherein the data lifespan timer is set based on at least one of: a maximum allowed transmission latency, an established radio link control, RLC, configuration and a transport channel block error rate, BLER.

6. The method of claim 1, further comprising:

when the WTRU receives feedback information indicating that the E-DCH data block was successfully received by the node-B, the E-DCH data block is discarded before the data lifespan timer expires.

7. In a wireless communication system including a WTRU and at least one node-B, the WTRU using at least one data lifespan timer to support enhanced dedicated channel, E-DCH, data transmission, the WTRU comprising:

a buffer for storing an E-DCH data block to be transmitted;

a data lifespan timer for monitoring a lifespan of the E-DCH data block;

a H-ARQ process for transmitting the E-DCH data block; and

a controller in communication with the buffer and the data lifespan timer, wherein when the data lifespan timer nears expiration, the controller is configured to determine whether physical resources have been allocated for transmission of the E-DCH data block, send an emergency channel allocation request to a node B if the physical resources have not been allocated, and give transmission priority to the E-DCH data block if the physical resources have been allocated, and when the data lifespan timer expires, the controller is configured to discard the E-DCH data block.

8. The WTRU of claim 7 wherein the WTRU sends a message to the node-B indicating that the E-DCH data block has been discarded and that the H-ARQ process is available.

9. The WTRU of claim 7 wherein the WTRU sends a message to a radio network controller, RNC, indicating that the data lifespan timer has expired.

10. The WTRU of claim 7 wherein the controller initiates a standard H-ARQ operation for transmission of the E-DCH data block if the E-DCH data block has been previously transmitted and the data lifespan timer is not close to expiring.

11. The WTRU of claim 7 wherein the data lifespan timer is configured for each of a plurality of transport channels TrCHs.

12. The WTRU of claim 7 wherein the data lifespan timer is configured for each of a plurality of logical channels.

13. The WTRU of claim 7 wherein the controller sets the data lifespan timer based on at least one of: a maximum allowed transmission latency, a configuration of the established radio link control, RLC, and a transport channel data block error rate, BLER.

14. The WTRU of claim 7 wherein the controller is configured to discard the E-DCH data block before the data lifespan timer expires when the WTRU receives feedback information indicating that the E-DCH data block has been successfully received by the node-B.