In a wireless communication system including a wireless transmit/receive unit (WTRU) (102) which transfers data to a Node-B (104), data transmission parameters such as modulation and coding (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 (102) and the Node-B (104) are initiated and released, as required. The WTRU (102) transmits and retransmits data to the Node-B (104) through an enhanced uplink (EU) dedicated channel (E-DCH) (108) in accordance with data feedback information received from the Node-B (104). The WTRU (102) 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 (102) initiates an EU transmission to the Node-B (104), which identifies the assigned H-ARQ process, TBS size and MCS.

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

A method and apparatus for assigning automatic repeat request (ARQ)/hybrid-automatic repeat request (H-ARQ) processes in a wireless transmit/receive unit (WTRU) to support enhanced uplink (EU) data transmissions. After parameters associated with the ARQ/H-ARQ processes are configured, the WTRU assigns an ARQ/H-ARQ process for selected data. After transmitting the data, the WTRU determines whether feedback information for the data has been received. The WTRU releases the ARQ/H-ARQ process if an acknowledgement (ACK) message has been received, and retransmits the data if a non-acknowledgement (NACK) message or no feedback information has been received in a predetermined time period while incrementing a transmission counter in the WTRU. When an ARQ/H-ARQ transmission limit has been reached, the WTRU may discard the data or reinitiate the transmission. An ARQ/H-ARQ process assigned for transmission of lower priority data may be preempted for transmission of higher priority data when there is no available ARQ/H-ARQ process.

Method and apparatus for assigning hybrid-automatic repeat request processes

The invention relates to a method for reconfiguring zones of a cell sector in a cellular mobile communication system employing a frequency division multiplex access scheme comprising the steps of separating a cell sector into zones of a predetermined size, allocating radio resources to users located in the zones, and altering the predetermined zone size upon a change of a radio resource management parameter. The invention also relates to a base station of a cellular mobile communication system.

Neighboring cell interference management in SC-FDMA

Future mobile communication systems will be designed to support a wide range of data rates with complex quality of service matrix. It is becoming more challenging to optimize the radio resource management and maximise the system capacity whilst meeting the required quality of service from user's point of view. Traditional schemes have approached this problem mainly focusing on resources within a cell and to large extent ignoring effects of multi-cell architecture. This paper addresses the influence of multi-cell interference on overall radio resource utilisation and proposes a novel approach, setting a new direction for future research on resource scheduling strategies in a multi-cell system. It proposes a concept called load matrix (LM) which facilitates joint management of interference within and between cells for allocation of radio resources. Simulation results show significant improvement in the resource utilization and overall network performance. Using the LM strategy, average cell throughput can be increased as much as 30% compared to a benchmark algorithm. Results also show that maintaining cell interference within a margin instead of a hard target can significantly improve resource utilization.

An Efficient Resource Allocation Strategy for Future Wireless Cellular Systems

This paper contains an evaluation of three different time and code division schedulers, for data transmission on enhanced dedicated channel (E-DCH) in WCDMA uplink. Time scheduling on E-DCH is possible thanks to fast node B scheduling operation on a transmission time interval (TTI) basis. Time scheduling allows for allocating users for transmission with instantaneously high data rates, and possibly when they experience favourable channel conditions. The system capacity can therefore be increased, also because interference generated to other cells is reduced. We apply a combined time and code division scheduling strategy in three different cases: a "blind fair throughput" scheduler (BFT), a "maximise transmit power efficiency" scheduler (MTPE) and a "channel-state aware fair throughput" scheduler (CSAFT). The two latter schedulers utilise an appositely defined uplink channel quality indicator (UCQI) to exploit channel-state information in the packet scheduling procedure. While the MTPE scheduler maximises cell throughput at the cost of at low degree of fairness between users, the CSAFT algorithm is shown to offer an appealing trade-off between users' fairness and throughput maximisation. Under a specific outage constraint for the packet call throughput, the capacity gain of the CSAFT scheduler over a node B code division scheduler is 17% and 30% for vehicular A and pedestrian A channel profile at 3 km/h, respectively. The estimated capacity increase compared to a reference RNC-based scheduler is estimated between 50% and 80%, also depending on the propagation scenario.

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Combined time and code division scheduling for enhanced uplink packet access in WCDMA

The performance of WCDMA uplink systems deploying Node B based scheduling and fast hybrid ARQ (HARQ) retransmission protocols is studied With fast Node B scheduling and fast L1 HARQ schemes, both the uplink packet scheduling functionality and the entity controlling the retransmission mechanism are moved from the radio network controller (RNC) to the Node B A Node B scheduling algorithm is proposed to increase the utilisation of the allocated uplink resources; this is achieved by making use of already existing information about the transmitted data rate of the UEs Moreover, fast L1 HARQ schemes make retransmissions less costly from a delay perspective compared to an equivalent RNC controlled ARQ mechanism Therefore, the physical channel can be operated with somewhat higher error probability, which converts directly into enhanced system capacity The potential capacity gain from fast L1 Node B controlled HARQ strategies and fast Node B scheduling operation is estimated by means of an analytical study, as well as system level simulations The combined gain obtained by jointly deploying fast Node B scheduling and fast L1 HARQ retransmission schemes is estimated in the range from 25% to 60%, depending on the mobility scenario Fast Node B scheduling and L1-based HARQ protocols are included in 3GPP's "Feasibility Study for Enhanced Uplink for UTRA FDD" (TR 25896 V112, 2003)

Performance of fast Node B scheduling and L1 HARQ schemes in WCDMA uplink packet access

In this paper, we study the operation of release'99 packet scheduler of the UMTS system. We focus on the uplink direction of data transmission. The aim is to investigate the performance of the packet scheduler data scheduling on dedicated transport channels. We emphasize in particular a power based packet scheduler (PS) with fair resource sharing. The PS performance has been evaluated in a time-dynamic network simulator with packet data users characterized by a bursty source traffic model. We shortly describe the source traffic model and the network simulator. The results concentrate on the uplink noise rise (NR) behavior for different settings of PS related timers and show that a reduction of some of these timers to allow faster scheduling can increase the network capacity. However, the results also demonstrate that this potential capacity gain is achievable only for bursty and high user equipment (UE) source data rate.

http://ieeexplore.ieee.org/iel5/8574/27150/01207190.pdf

K. Dimou

Papers

Performance of fast Node B scheduling and L1 HARQ schemes in WCDMA uplink packet access

Performance of uplink packet services in WCDMA