The explosive demand for data has called for solution approaches that range from spectrally agile cognitive radios with novel spectrum sharing, to use of higher frequency spectrum as well as smaller and denser cell deployments with diverse access technologies, referred to as heterogeneous networks (HetNets). Simultaneously, advances in electronics and storage, has led to the advent of wireless devices equipped with multiple radio interfaces (e.g. WiFi, WiMAX, LTE, etc.) and the ability to store and efficiently process large amounts of data. Motivated by the convergence of HetNets and multi-platform radios, we propose HetNetwork Coding as a means to utilize the available radio interfaces in parallel along with network coding to increase wireless data throughput. Specifically we explore the use of random linear network coding at the network layer where packets can travel through multiple interfaces and be received via multihoming. Using both simulations and experimentation with real hardware on WiFi and WiMAX platforms, we study the scaling of throughput enabled by such HetNetwork coding. We find from our simulations and experiments that the use of this method increases the throughput, with greater gains achieved for cases when the system is heavily loaded or the channel quality is poor. Our results also reveal that the throughput gains achieved scale linearly with the number of radio interfaces at the nodes.
There have been some previous studies related to offloading of cellular traffic on WiFi links, such as @cite_11 , @cite_19 where authors implement the offloading only at the destination cell by choosing a set of nodes, which can receive the data from the destination base station on behalf of the destination node and then forward it to the destination node via WiFi links. propose a system called iCAR (integrated cellular and ad-hoc relaying system) @cite_27 , where ad-hoc relay nodes are strategically placed inside a cellular network to offload the traffic from congested cells to non-congested cells. @cite_34 suggest various schemes for using an ad-hoc network in a cellular packet data network, but in these schemes the base station is actively involved with the ad-hoc network in improving the performance. The scheme proposed in this paper does not require any explicit coordination between the cellular and WiFi networks, but instead relies on the multiplatform radio enabled wireless nodes to adapt their packet processing at the network layer.
@cite_19 @cite_27 @cite_34 @cite_11
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The paper presents an ad-hoc architecture for wireless sensor networks and other wireless systems similar to them. In this class of wireless system the physical resource at premium is energy. Bandwidth available to the system is in excess of system requirements. The approach to solve the problem of ad-hoc network formation here is to use available bandwidth in order to save energy. The method introduced solves the problem of connecting an ad-hoc network. This algorithm gives procedures for the joint formation of a time schedule (similar to a TDMA schedule) and activation of links therein for random network topologies. This self-organization method is energy-sensitive, distributed, scalable, and able to form a connected network rapidly. Integrated cellular and ad hoc relaying systems (iCAR) is a new wireless system architecture based on the integration of cellular and modern ad hoc relaying technologies. It addresses the congestion problem due to unbalanced traffic in a cellular system and provides interoperability for heterogeneous networks. The iCAR system can efficiently balance traffic loads between cells by using ad hoc relaying stations (ARS) to relay traffic from one cell to another dynamically. This not only increases the system's capacity cost effectively, but also reduces the transmission power for mobile hosts and extends system coverage. We compare the performance of the iCAR system with conventional cellular systems in terms of the call blocking dropping probability, throughput, and signaling overhead via analysis and simulation. Our results show that with a limited number of ARSs and some increase in the signaling overhead (as well as hardware complexity), the call blocking dropping probability in a congested cell and the overall system can be reduced. While several approaches have been proposed in literature for improving the performance of wireless packet data networks, a recent class of approaches has focused on improving the underlying wireless network model itself. Several of such approaches have shown that using peer-to-peer communication, a mode of communication used typically in ad-hoc wireless networks, can result in performance improvement in terms of both throughput and energy consumption. However, the true impact of using the ad-hoc network model in wireless packet data networks has neither been comprehensively studied, nor characterized. In this paper, we investigate the benefits of using an ad-hoc network model in cellular wireless packet data networks. We find that while the ad-hoc network model has significantly better spatial reuse characteristics, the improved spatial reuse does not translate into better throughput performance. Furthermore, although considerable improvement is seen in energy consumption performance, we observe that using the ad-hoc network model as-is might actually degrade the throughput performance of the network. We identify and discuss the reasons behind these observations. Finally, using the insights gained through our performance evaluations, we discuss strawman versions of three techniques which when used in tandem with the ad-hoc network model result in better throughput, energy consumption, fairness, and mobility-resilience characteristics. Through our simulation results, we motivate that using the ad-hoc network model in conventional wireless packet data networks is a promising approach when the network model is complemented with appropriate mechanisms.