Multiuser Resource Allocation Maximizing the Perceived Quality
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Research Article Multiuser Resource Allocation Maximizing the Perceived Quality Andreas Saul and Gunther Auer DOCOMO Euro-Labs, Landsberger Str. 312, 80687 Munich, Germany Correspondence should be addressed to Andreas Saul, [email protected] Received 1 August 2008; Accepted 24 January 2009 Recommended by Thomas Michael Bohnert Multiuser resource allocation for time/frequency slotted wireless communication systems is addressed. A framework for application driven cross-layer optimization (CLO) between the application (APP) layer and medium access control (MAC) layer is developed. The objective is to maximize the user-perceived quality by jointly optimizing the rate of the information bit-stream served by the APP layer and the adaptive resource assignment on the MAC layer. Assuming adaptive transmission with long-term channel state information at the transmitter (CSIT), we present a novel CLO algorithm that substantially reduces the amount of parameters to be exchanged between optimizer and layers. The proposed CLO framework supports user priorities where premium users perceive a superior service quality and have a higher chance to be served than ordinary users. Copyright © 2009 A. Saul and G. Auer. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction With the high envisaged data rates of beyond 3rd generation (B3G) wireless communication systems [1, 2], multimedia broadband applications can be offered to mobile users. Multimedia applications are characterized by a multitude of data rate and quality of service (QoS) requirements. On the other hand, owing to the nature of the mobile radio channel, frequency selective fading, distance dependent path loss, and shadowing cause vast variations in the attainable spectral efficiency per user. The objective of multiuser resource allocation is to assign the available resources over the shared wireless medium to mobile users running different applications [3]. Orthogonal frequency division multiple access (OFDMA) provides orthogonal transmission slots in time and frequency, which may be flexibly assigned to the individual users [4, 5]. In B3G systems, this feature is exploited by the medium access control (MAC) layer to freely distribute the available bandwidth between users [6]. Provided channel state information at the transmitter (CSIT) is available, the number of transmitted information bits per slot can be adjusted to the channel conditions of a particular user. The application (APP) layer outputs encoded applications, for example, a video stream. For the scalable video
coding (SVC) extension [7, 8] of the advanced video coding (AVC) standard H.264/MPEG-4 AVC the stream may be received with a variable information bit rate. Other kinds of video streams may be encoded or transcoded [9] with the desired data rate. In general, any application may be delivered with variable information bit rate, all
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