Broadband wireless access (BWA) networks, such as LTE and WiMAX, are inherently lossy due to wireless medium unreliability. Although the Hybrid Automatic Repeat reQuest (HARQ) error-control method recovers from packet loss, it has low transmission efficiency and is unsuitable for delay-sensitive applications. Alternatively, network coding techniques improve the throughput of wireless networks, but incur significant overhead and ignore network constraints such as Medium Access Control (MAC) layer transmission opportunities and physical (PHY) layer channel conditions. The present study provides analysis of Random Network Coding (RNC) and Systematic Network Coding (SNC) decoding probabilities. Based on the analytical results, SNC is selected for developing an adaptive network coding scheme designated as Frame-by-frame Adaptive Systematic Network Coding (FASNC). According to network constraints per frame, FASNC dynamically utilizes either Modified Systematic Network Coding (M-SNC) or Mixed Generation Coding (MGC). An analytical model is developed for evaluating the mean decoding delay and mean goodput of the proposed FASNC scheme. The results derived using this model agree with those obtained from computer simulations. Simulations show that FASNC results in both lower decoding delay and reduced buffer requirements compared to MRNC and N-in-1 ReTX, while also yielding higher goodput than HARQ, MRNC, and N-in-1 ReTX.

Energy conservation is the key factor driving the trend toward green next-generation wireless networks. Existing studies have shown that cooperative communications can significantly reduce energy consumption. Most of these studies simplistically assume that all of the nodes in the network will cooperatively transmit. However, in practice, nodes may not always be altruistic and reject collaboration. Accordingly, this study proposes a reputation auction framework to provide indirect reciprocity for stimulating node cooperation in green wireless networks which also adapts to various network dynamics. Two sealed-bid auction schemes are presented to efficiently and fairly allocate node reputation for single and multiple relay scenarios resulting in energy savings arising from application of the considered indirect reciprocity model. The simulation results show that the proposed reputation auction framework can achieve higher energy efficiency compared to non-cooperative schemes and only slightly increases signaling overhead.

WiMAX and WiFi have emerged as promising broadband access solutions for the latest generation of wireless MANs and LANs, respectively. Their complementary features enable the use of WiMAX as a backhaul service to connect multiple dispersed WiFi hotspots to the Internet. This study proposes an integrated architecture utilizing a novel WiMAX/WiFi Access Point (W2-AP) device to effectively combine the WiMAX and WiFi technologies. In the proposed architecture, the protocol operation of the WiFi hotspots is the same as that of the WiMAX system. As a result, the WiFi network can support connection-oriented transmissions and QoS in a similar fashion to the WiMAX system, and thus a considerable improvement in the delay performance is obtained. The numerical results obtained using a Qualnet simulator confirm both the effectiveness and the efficiency of the proposed architecture.

An integrated EPON/WiMAX network has been an attractive attention due to its features of achieving stable backhaul transmissions to WiMAX users and reducing the expenditure of network deployment. In implementing such a network, realizing a scheduling mechanism capable of sharing the available bandwidth between the heterogeneous Ethernet and WiMAX traffic in an effective manner is problematic. In the present study, this problem is addressed by using a game-theoretic-based scheme comprising a bankruptcy game and a bargaining game to perform an intra-ONU scheduling function at each ONU within the network. In the proposed approach, each ONU distributes the total amount of bandwidth allocated by the OLT between the Ethernet and WiMAX traffic buffers in accordance with the results of the bankruptcy game. By applying bargaining games, the allocated bandwidth is then further distributed to the different traffic classes within the Ethernet or WiMAX traffic in accordance with their QoS requirements. The simulation results confirm the validity and effectiveness of the proposed approach.