Abstract-Traditional approaches to transmit information reliably over an error-prone network employ either Forward Error Correction (FEC) or retransmission techniques. In this paper we consider an application of network coding to increase the bandwidth efficiency of reliable broadcast in a wireless network. In particular, we propose two schemes which employ network coding to reduce the number of retransmissions as a result of packet losses. Our proposed schemes combine different lost packets from different receivers in such a way that multiple receivers are able to recover their lost packets with one transmission by the source. The advantages of the proposed schemes over the traditional wireless broadcast are shown through simulations and theoretical analysis. Specifically, we provide a few results on the retransmission overhead of the proposed schemes under different channel conditions.

In recent years, Wireless Local Area Networks (WLAN) have become the premier choice for many homes and enterprises. WiMAX (Worldwide Interoperability forMicrowave Access) has also emerged as the wireless standard that aims to deliver data over long distances, and can potentially provide wireless broadband access as an alternative to the wired cable and DSL networks. Parallel with the surge of wireless networks is the explosive growth of multimedia applications. Therefore, it is important to explore efficient methods for delivering multimedia data in such wireless settings. In this paper, we propose a network coding based scheduling policy to be used at WLAN-like Access Point (AP) or at a WiMAX-like broadcast station that optimizes the multimedia transmission in both broadcast and unicast settings. In particular, the contributions of this paper include (a) a framework for increasing the bandwidth efficiency of broadcast and unicast sessions in a wireless network based on network coding techniques and (b) an optimized scheduling algorithm based on the Markov Decision Process (MDP) to maximize the quality of multimedia applications. Simulations and theoretical results demonstrate the advantages of our approach over the conventional techniques.

We consider the problem of joint network coding and packet scheduling for multimedia transmission from the Access Point (AP) to multiple receivers in 802.11 networks. The state of receivers is described by a hidden Markov model and the AP acts as a decision maker which employs a partially observable Markov decision process (POMDP) to optimize the media transmission. Importantly, we introduce a simulation-based dynamic programming algorithm as a solution tool for our POMDP abstract. Our simulation-based algorithm simplifies the modeling process as well as reduces the computational complexity of the solution process. Our simulation results demonstrate that the proposed scheme provides higher performance than the network coding scheme without using optimization techniques and traditional retransmission scheme.

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