Browsing by Author "Yang, Wen-Fang"

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A Cooperative Multi-Group Priority MAC Protocol for Multi-Packet Reception Channels
(2009-11-01)
Yang, Wen-Fang
;
Wu, Jwo-Yuh
;
Wang, Li-Chun
;
Lee, Ta-Sung
;
電子工程學系及電子研究所
Medium access control (MAC) protocol design for cooperative networks over multi-packet reception (MPR) channels is a challenging topic, but has not been addressed in the literature yet. In this paper, we propose a cooperative multi-group priority (CMGP) based MAC protocol to exploit the cooperation diversity for throughput enhancement over MPR channels. The proposed approach can bypass the computationally-intensive active user identification process. Moreover, our method can efficiently utilize the idle periods for packet relaying, and can thus effectively limit the throughput loss resulting from the relay phase. By means of a Markov chain model, the worst-case throughput analysis is conducted. The results allow us to investigate the throughput performance of the proposed CMGP protocol directly in terms of the MPR channel coefficients. Simulation results confirm the system-wide throughput advantage achieved by the proposed scheme, and also validate the analytic results.
A Multi-Group Priority Based Cooperative MAC Protocol for Multi-Packet Reception Channels
(2009)
Yang, Wen-Fang
;
Wu, Jwo-Yuh
;
Wang, Li-Chun
;
Lee, Ta-Sung
;
電信工程研究所
Medium access control (MAC) protocol design for cooperative networks over multi-packet reception (MPR) channels is a challenging topic, but has not been addressed in the literature yet. In this paper, we propose a MAC protocol to exploit the cooperation diversity for throughput enhancement over MPR channels. The proposed approach can efficiently utilize the idle periods for packet relaying, and can thus effectively limit the throughput loss resulting from the relay phase. By means of a Markov chain model, the worst-case throughput analysis is conducted. Specifically, we derive (i) a closed-form upper bound for the throughput penalty of the direct link that is caused by the interference of concurrent packet relay transmission; (ii) a closed-form lower bound for the throughput gain that a user with packet transmission failure can benefit thanks to cooperative packet relaying. The results allow us to investigate the throughput performance of the proposed protocol directly in terms of the MPR channel coefficients. Simulation results confirm the system-wide throughput advantage achieved by the proposed scheme, and also validate the analytic results.
A multigroup priority queueing MAC protocol for wireless networks with multipacket reception
(2008)
Yang, Wen-Fang
;
Wu, Jwo-Yuh
;
Wang, Li-Chun
;
Lee, Ta-Sung
;
電信工程研究所
Relying on a simple flag-assisted mechanism, a multigroup priority queueing (MGPQ) medium access control (MAC) protocol is proposed for the wireless networks with multipacket reception ( MPR). The proposed MGPQ scheme is capable of overcoming two major performance bottlenecks inherent in the existing MPR MAC protocols. First, the proposed solution can automatically produce the list of active users by observing the network traffic conditions, remove the need of active user estimation algorithm, and thus can largely reduce the algorithm complexity. Second, the packet blocking constraint imposed on the active users for keeping compliant with prediction is relaxed. As a result, the proposed MGPQ is not only applicable to both homogeneous and heterogeneous cases, but also outperforms the existing MPRMAC protocols. Simulation results show that the network throughput can be improved by 40% maximum and 14% average as compared with the well- known dynamic queue (DQ) MAC protocol.
An Enhanced Multi-Packet Reception MAC Protocol: Cooperative Approach
(2008)
Yang, Wen-Fang
;
Wu, Jwo-Yuh
;
Lee, Ta-Sung
;
電信工程研究所
;
Institute of Communications Engineering
An enhanced medium access control (MAC) protocol for wireless networks with multi-packet reception (MPR) capability is proposed. The proposed protocol is based on the dynamic multi-group priority queueing protocol recently introduced in [I] to exploit the cooperative diversity for improving the system throughput. Two kinds of throughput losses, i.e., over-loaded loss and under-loaded loss, are defined first to clarify the opportunity of improvement. it Markov chain analysis is provided as the theoretical background. It is shown that the under-loaded loss can be compensated by cooperation among users in light traffic environment, and the system throughput can be improved accordingly. Simulations further compare the delay and packet loss ratio with and without cooperation, it is found the average performance is improved too.
Multi-group priority queueing MAC protocol for multipacket reception channel
(2008)
Yang, Wen-Fang
;
Wu, Jwo-Yuh
;
Wang, Li-Chun
;
Lee, Ta-Sung
;
電信工程研究所
Relying on a simple flag-assisted mechanism, a multi-group priority queueing (MGPQ) medium access control (MAC) protocol is proposed for the multipacket reception (MPR) channel. The proposed MGPQ scheme is capable of overcoming two major performance bottlenecks inherent in the existing MPR MAC protocols. First, the proposed solution can automatically produce the list of active users by observing the network traffic conditions, removes the need of active user estimation algorithm, and thus can largely reduce the algorithm complexity. Second, the packet blocking constraint imposed on the active users for keeping compliant with prediction is relaxed. As a result, the proposed MGPQ is not only applicable to both homogeneous and heterogeneous cases, but also outperforms the existing MPR MAC protocols. Simulation results show that the network throughput can be improved by 40% maximum and 14% average as compared with the well known dynamic queue (DQ) MAC protocol.
Signal modulus design for blind source separation via algebraic known modulus algorithm: A perturbation perspective
(2008)
Wu, Jwo-Yuh
;
Yang, Wen-Fang
;
Wang, Li-Chun
;
Lee, Ta-Sung
;
電信工程研究所
This brief considers blind signal source separation via algebraic known modulus algorithm. It is shown that through proper sign at modulus design the estimation accuracy of the beamforming vector, as well as the performance of signal separation, can be improved. Specifically, based on a matrix perturbation analysis we propose a criterion, in the form of minimizing the maximal singular value of the modulus code matrix, for enhancing robustness of the beamforming vector against measurement noise. A closed-form solution is then derived and its performance is tested through numerical simulation.