Method and apparatus for dynamically adjusting data transmission parameters and controlling H-ARQ processes
In a wireless communication system including a wireless transmit/receive unit (WTRU) which transfers data to a Node-B, data transmission parameters such as modulation and coding scheme (MCS) and transport block set (TBS) size are dynamically adjusted on a transmission time interval (TTI) basis, and hybrid-automatic repeat request (H-ARQ) processes used to control the transfer of data between the WTRU and the Node-B are initiated and released, as required. The WTRU transmits and retransmits data to the Node-B through an enhanced uplink (EU) dedicated channel (E-DCH) in accordance with data feedback information received from the Node-B. The WTRU queues data for transmission, and determines a transmission status of the data. The transmission status is set to one of “new transmission,” “successful transmission,” “retransmission” and “restarted transmission.” For each TTI, the WTRU initiates an EU transmission to the Node-B which identifies the assigned H-ARQ process, TBS size and MCS.
1. A method of dynamically adjusting data transmission parameters for transmission of enhanced dedicated channel (E-DCH) data, the method comprising:
queuing E-DCH data in a buffer;
selecting E-DCH data from the buffer available for transmission;
determining whether or not the selected E-DCH data was previously transmitted;
if it is determined that the selected E-DCH data was not previously transmitted selecting a modulation and coding scheme (MCS) within an allowed limit;
assigning a hybrid automatic repeat request (H-ARQ) process;
generating at least one enhanced uplink medium access control (MAC-e) protocol data unit (PDU); and
initiating an enhanced uplink transmission which identifies the H-ARQ process and the MCS.
2. A method of dynamically adjusting data transmission parameters for transmission of enhanced dedicated channel (E-DCH) data, the method comprising:
queuing E-DCH data in a buffer;
selecting E-DCH data from the buffer available for transmission;
determining whether or not the selected E-DCH data was previously transmitted;
if it is determined that the selected E-DCH data was not previously transmitted selecting a transport block set (TBS) size within an allowed limit;
assigning a hybrid automatic repeat request (H-ARQ) process;
generating at least one enhanced uplink medium access control (MAC-e) protocol data unit (PDU); and
initiating an enhanced uplink transmission which identifies the H-ARQ process and the TBS size.
3. A method of dynamically adjusting data transmission parameters for transmission of enhanced dedicated channel (E-DCH) data, the method comprising:
queuing E-DCH data in a buffer;
selecting E-DCH data for transmission;
determining whether or not the selected E-DCH data is new data; and
if the data is new data,
selecting a data transmission parameter within an allowed limit;
assigning a hybrid automatic repeat request (H-ARQ) process for transmission of the data;
transmitting the data identifying the data transmission parameter; and
initializing a transmission count.
4. The method of claim 3 wherein the data transmission parameter is modulation and coding scheme.
5. The method of claim 3 wherein the data transmission parameter is a transport block set size.
6. The method of claim 3 further comprising:
if it is determined that the selected data is not new data,
determining whether a retransmission count of the selected data is less than a maximum number of allowed retransmissions; and
if the retransmission count is less than the maximum, retransmitting the data and incrementing the retransmission count.
7. The method of claim 6 further comprising:
if the retransmission count is not less than the maximum, discarding the data and releasing the H-ARQ process.
8. The method of claim 6 further comprising:
if the retransmission count is not less than the maximum, restarting the H-ARQ process transmission while initializing the retransmission count.
9. The method of claim 8 wherein a new data indicator is transmitted to indicate a restart of the transmission.
10. The method of claim 3 further comprising:
if the data is not new data, determining whether a lifespan timer for the selected data has expired, whereby the selected data is discarded when the lifespan timer expires.
11. A wireless transmit/receive unit (WTRU) for dynamically adjusting data transmission parameters for transmission of enhanced dedicated channel (E-DCH) data, the WTRU comprising:
a buffer for queuing E-DCH data;
a retransmission counter for tracking number of transmissions of same data block;
a transmitter and a receiver for transmitting and receiving the E-DCH data; and
a controller for selecting data and transmission parameters for transmission of the E-DCH data and assigning a hybrid automatic repeat request (H-ARQ) process for transmission of the data,
whereby if the data is new data the controller selects a data transmission parameter within an allowed limit and initializes a retransmission count.
12. The WTRU of claim 11 wherein the data transmission parameter is modulation and coding scheme.
13. The WTRU of claim 12 wherein the data transmission parameter is a transport block set size.
14. The WTRU of claim 12 wherein if the selected data for transmission is not new data, the controller determining whether the retransmission count of the selected data is less than a maximum number of allowed retransmissions, and if the retransmission count is less than the maximum, the controller retransmits the data incrementing the retransmission count.
15. The WTRU of claim 14 wherein same transmission parameter is used for the retransmission.
16. The WTRU of claim 14 wherein more robust modulation and coding scheme is used for the retransmission.
17. The WTRU of claim 16 wherein a transport block is segmented into two or more transport blocks.
18. The WTRU of claim 14 wherein if the retransmission count is not less than the maximum, the data is discarded and associated H-ARQ process is released.
19. The WTRU of claim 14 wherein if the retransmission count is not less than the maximum, the controller restarts the H-ARQ process transmission while initializing the retransmission count.
20. The WTRU of claim 19 wherein a new data indicator is transmitted to indicate a restart of the transmission.
21. The WTRU of claim 19 wherein same data transmission parameters are used for the restarted transmission.
22. The WTRU of claim 19 wherein more robust modulation and coding scheme is used for the restarted transmission.
23. The WTRU of claim 11 further comprising:
a life span timer for tracking life span of the data, whereby the controller discards the data when the lifespan timer expires.