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  1. Cooperative Diversity Using Repeat-Punctured Turbo Codes
  2. Efficient Management of Clock Drift in Preamble Sampling MAC Protocols for Wireless Sensor Networks
  3. A Duopoly Pricing Model for Wireless Mesh Networks Under Congestion-Sensitive Users

Cooperative Diversity Using Repeat-Punctured Turbo Codes by J. M. Mouatcho Moualeu, H. Xu and F. Takawira
Abstract: When mobiles cannot accommodate multiple antennas due to size, hardware complexity and/or other constraints, space-time coding cannot be used to provide uplink transmit diversity. Recently, cooperative diversity has been introduced where mobiles achieve uplink transmit diversity by relaying each other’s messages. A particularly powerful variation of this principle is coded cooperation which partitions the codewords of each mobile and transmits portions of each codeword through independent fading channels. Coded cooperation framework has been easily extended using turbo codes, since cooperative coding contains two codes components. It has been shown that the conventional turbo codes can be improved by repetition and puncturing. This paper presents another extension to coded cooperation. We investigate the application of repeat-punctured turbo codes in coded cooperation. The analysis and simulation results show that the proposed scheme achieves approximately 2 dB gain for a 12 dB inter-user channel at a BER of 10-4 order.
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Efficient Management of Clock Drift in Preamble Sampling MAC Protocols for Wireless Sensor Networks by C. E. Tönsing and G. P. Hancke
Abstract: In this paper, the design of an energy-efficient Medium Access Control (MAC) protocol for low traffic Wireless Sensor Networks (WSNs) is presented. The protocol, Dynamic Preamble Sampling MAC (DPS-MAC), is based on the existing preamble sampling MAC layer solutions for WSNs. Unlike its predecessors, DPS-MAC does not cater for the worst case clock drift but rather, it dynamically adjusts its operation to the clock drift experienced between any two communicating nodes. In this way, the energy previously expended on overcoming the problem of clock drift is reduced, leading to longer node and network lifetimes.
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A Duopoly Pricing Model for Wireless Mesh Networks Under Congestion-Sensitive Users by H. Zhu, A. Nel and W. Clarke
Abstract: The development of Wireless Local Area Network (WLAN) technologies offers a novel platform for IP-based service resale via Wireless Mesh Networks (WMNs) that provide high network coverage and lower infrastructure cost. In this IP-based service resale business, the Access Point (AP) providers set their pricing policies as IP-based service resellers to maximize their profits, while the resale-users (end users of the WMNs) who are price- and quality-of-service (QoS)- sensitive, respond to AP providers’ pricing policies by controlling their usage. In this paper we study a two AP providers price competition in a WMN. The two AP providers offer IP-based service for possibly different prices and QoS in terms of mean packet delay. The resale-users’ choice between the APs is based on their compensated utility. We consider a two stage game among the two AP providers and their resale-users. In stage 1, the AP providers set their prices to maximize their profits respectively. In stage 2, given the prices and QoS offered by both AP providers, the resale-users decide which AP to seek service from or opt out of both APs. Then the game returns to stage 1, in which both AP providers adjust their optimal prices based on the decisions of the resale-users to seek equilibrium among themselves and their resale-users. With this game theoretical approach, we develop an analytical framework to find the Nash equilibrium points from which two APs and resale-users would not move from.
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