المؤلفون: Liu, Yang, Wang, Wenbo, Peng, Mugen, Wei, Dongyan

المصدر: Wireless Networks (10220038); Jan2013, Vol. 19 Issue 1, p69-81, 13p

مصطلحات موضوعية: SUPERPOSITION principle (Physics), CELL phone systems, MULTICASTING (Computer networks), CONJOINT analysis, RATIO analysis

مستخلص: We propose a layered multicast transmission scheme with superposition coding for cellular systems, i.e., at a base station a basic multicast stream (BMS) and an enhanced multicast stream (EMS) are superimposed and transmitted, the same BMS is repeatedly transmitted multiple times to ensure most users in the cell receive basic qualities of the service, while in each transmission different EMSs are transmitted to make the users with good channel conditions receive higher qualities of the service. In this paper, the optimal joint rate and power allocation for the layered multicast scheme is studied. Specifically, we first give a proof on the claim that the system delay of a BMS is minimized if the transmission rate of the BMS is set according to a fixed user selection ratio in each transmission. Then subject to fixed transmit power and power allocation, we derive the optimal transmission rate of a BMS that minimizes the system delay of the BMS, and the optimal transmission rate of an EMS that maximizes the average throughput of the EMS. Finally, by balancing the tradeoff between the system delay of a BMS and the average throughput of an EMS, we find the optimal joint rate and power allocation for the layered multicast scheme. Numerical results show that the optimized layered multicast scheme outperforms the conventional schemes in terms of the system delay of a BMS and the average throughput of an EMS. [ABSTRACT FROM AUTHOR]

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المؤلفون: Wei, Dongyan¹ (AUTHOR) weidongyan.cn@gmail.com, Wang, Wenbo¹ (AUTHOR), Peng, Mugen¹ (AUTHOR), Liang, Dong¹ (AUTHOR), Liu, Yang¹ (AUTHOR)

المصدر: International Journal of Communication Systems. Jul2011, Vol. 24 Issue 7, p911-924. 14p. 1 Diagram, 1 Chart, 6 Graphs.

مصطلحات موضوعية: *BROADCASTING industry, *WIRELESS communications, *QUALITY of service, *DISTRIBUTION (Probability theory), *DATA transmission systems, *MULTIMEDIA communications, *SUPERPOSITION principle (Physics)

مستخلص: In wireless broadcast system, where feedback is limited and channel state information is only available at the receiver side, layered broadcasting approach has been proposed to fully utilize the channel resources by providing different levels of service quality to users with different channel conditions. However, no upper bound has been given yet to show how the layered broadcast scheme will outperform the conventional broadcast (CB) scheme. In this paper, system average achievable rate (SAAR) is defined as the mean achievable rate of all users within the coverage. Based on continuum superposition coding (SC) with infinite layers, the upper bound of the SAAR of layered broadcasting is given by the derivation of the optimal power distribution function among the superposed layers. The results show that, by promoting the experience of stronger users (users with better channel conditions) without seriously degrading the performance of weaker users (users with worse channel conditions), layered broadcasting approach greatly increases the average system performance. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]