[Show abstract][Hide abstract] ABSTRACT: In this paper, a utility-based throughput maximization and complexity-reduction (U_TMCR) scheduling scheme is proposed for downlink multiuser multiple-input-multiple-output orthogonal frequency-division multiple-access (MIMO-OFDMA) systems. The U_TMCR scheme allocates subchannels, antenna sequence, and modulation order to multimedia users with goals not only to maximize system throughput under quality-of-service (QoS) guarantee but to reduce computational complexity as well. Based on the channel quality and the QoS requirements of each user, the U_TMCR scheme designs a utility function for every user and formulates the scheduling into an optimization problem of overall system utility function subject to system constraints. It also contains a heuristic TMCR algorithm to efficiently solve the optimization problem. Simulation results show that the U_TMCR scheme achieves system throughput very close to the optimal solution by exhaustive search and higher than conventional schemes such as adaptive radio resource allocation (ARRA) and cross-layer design of packet scheduling (CDPS) by about 8% and 21%, respectively. The U_TMCR scheme also has a QoS satisfaction ratio that is better than the ARRA and CDPS schemes. Moreover, the U_TMCR scheme can reduce computational complexity. Generally, the total number of allocation trials of the U_TMCR scheme in a frame is smaller than that of the ARRA scheme by 6.25%-29.2%.
[Show abstract][Hide abstract] ABSTRACT: The paper proposes and analyzes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for IEEE 802.11 WLAN. The APP MAC scheme intends to support delay fairness for every station in each access, denoting small delay variance. It differentiates permission probabilities of transmission for stations which are incurred with various packet delays. This permission probability is designed as a function of the numbers of retransmissions and re-backoffs so that stations with larger packet delay are endowed with higher permission probability. Also, the scheme is analyzed by a Markov-chain analysis, where the collision probability, the system throughput, and the average delay are successfully obtained. Numerical results show that the proposed APP MAC scheme can attain lower mean delay and higher mean throughput. In the mean time, simulation results are given to justify the validity of the analysis, and also show that the APP MAC scheme can achieve more delay fairness than conventional algorithms.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a dynamic priority resource-allocation (DPRA) scheme is proposed for uplinks in IEEE 802.16 wireless communication systems. The DPRA scheme dynamically gives priority values to four types of service traffic based on their urgency degrees and allocates system radio resources according to their priority values. It can maximize the system throughput and satisfy differentiated quality-of-service (QoS) requirements. Furthermore, the DPRA scheme performs consistent allocation for packets of users to conform to the uplink frame structure of IEEE 802.16, to fulfill the QoS requirement, and to reduce the computational complexity. Simulation results show that the proposed DPRA scheme performs very close to the optimal method, which is by exhaustive search in system throughput, and it outperforms the conventional efficient and fair scheduling (EFS) algorithm in the performance measures such as system throughput, real-time polling service (rtPS) packet dropping rate, ratio of unsatisfied non-real-time polling service (nrtPS), and average transmission rate of the best effort (BE) service. In addition, the DPRA scheme takes only 1/1000 and 1/10 the computational times of the optimal method and the conventional EFS algorithm, respectively, thus making it more feasible for real applications.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a dynamic priority-based resource allocation (DPRA) scheme is proposed for uplinks in IEEE 802.16 wireless communication systems. The goal of the DPRA scheme is to maximize the system throughput while satisfying diverse QoS requirements. Four types of multimedia traffic are considered, where these multimedia traffic are given urgency degrees via dynamic priority values, and the radio resources are allocated according to their priority values. Also the DPRA scheme performs consistent allocation for packets with multimedia traffic in aspects of subchannel, modulation order, and power. Simulation results show that the proposed DPRA scheme outperforms the conventional algorithm in system throughput by an amount of 15%. The rtPS packet dropping rate of DPRA scheme is 70% lower than other schemes and satisfies QoS requirements. Besides, the proposed DPRA scheme can achieve less computational complexity and lower transmission overhead.
[Show abstract][Hide abstract] ABSTRACT: A centralized QoS guaranteed throughput enhancement (QoS GTE) scheduling scheme for downlink relay-assisted WiMAX networks is proposed. The QoSGTE consists of a transmission time based path selection algorithm (TTPSA), a service order based resource allocation algorithm (SO RAA), and a transmission concurrency decision algorithm (TCDA). The TT_PSA selects the path with the minimal transmission time for packets, which takes path loss, shadow fading, and interference into consideration. The SO RAA gives high priority to urgent users and maximizes throughput under QoS satisfaction. The TCDA carries out flexible resource reuse by deciding which relay station (RS) can transmit concurrently using the same frequency and time slots. Simulation results show that the proposed QoSGTE outperforms the scheme of without relay by an amount of 63% and that of the LMP by an amount of 28%, in the system throughput. The QoS GTE can also guarantee QoS requirements of real time services by 97%.
Communications, 2008. ICC '08. IEEE International Conference on; 06/2008
[Show abstract][Hide abstract] ABSTRACT: The paper proposes an adaptive radio resource allocation (ARRA) algorithm for downlink OFDMA/SDMA systems with goals to achieve quality of service (QoS) satisfied and throughput maximized. The ARRA algorithm considers multiple service classes of multimedia traffic and their diverse QoS requirements. It contains two parts, a dynamic priority adjustment scheme and a priority-based greedy (PBG) algorithm. The dynamic priority adjustment scheme gives high priority to urgent users and dynamically adjust the value frame by frame based on users' QoS requirement and queue occupancy. The PBG algorithm allocates the radio resource iteratively according to a cost value to maximize the system throughput while allocating enough resource to high-priority users. Simulation results show that the ARRA algorithm outperforms the conventional algorithms in terms of system throughput under the satisfaction of QoS requirements.
Communications, 2007. ICC '07. IEEE International Conference on; 07/2007
[Show abstract][Hide abstract] ABSTRACT: The letter proposes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for the IEEE 802.11e distributed WLAN supporting multimedia services. The APP MAC scheme adaptively gives differentiated permission probabilities to transmission stations which are in different access category and with various waiting delay. Simulation results show that the APP MAC scheme can improve the performance of multimedia WLAN, such as small voice packet dropping probability, low delay variation, and high system throughput, compared to conventional MAC algorithms