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One of the crucial challenges in practical wireless networks is how to provide robust communication over fading channels. Recently, cooperative communications have emerged as a promising approach to achieve spatial diversity and thereby reduce the negative effects of fading on wireless channels. Nevertheless, a few existing works indicate that deploying cooperative relays in large-scale wireless networks...
Energy consumption is one of the active research areas in wireless communication due to the limited battery attached to mobile devices. This paper describes an energy efficient network architecture for infrastructured wireless networks. The contributions of this paper are the study of a distributed localized algorithm for constructing Voronoi diagram followed by a network architecture based on Voronoi...
The selection of routes is an important issue in wireless networks when network coding is used. Existing research formulate network-coding-aware routing as a linear optimization program. However, deploying such method in real wireless networks is impractical. To solve this issue, in this paper, a practical network-coding aware routing protocol is proposed for unicast sessions in wireless networks...
Previous research on physical layer network coding (PNC) focuses on the improvements in bandwidth usage efficiency. In this paper, we propose a PNC-based node localization mechanism. When two signal sequences collide at the receiver, the starting point of collision is determined by the distances between the receiver and senders. When the signal interference results from two receivers are combined...
Internet mobility protocols are designed to support handover between different wireless networks. Many of them, such as Mobile IPv6, suffer problems such as high handover latency, high packet overhead, high packet loss during handoff, requirement for infrastructure change, etc. To solve these problems, SEamless MObility using SHIM6 (SEMO6), a multihoming based mobility protocol framework for host...
Cooperative positioning algorithms have been recently introduced to overcome the limitations of traditional methods, relying on GNSS or other terrestrial infrastructure. In particular, SPAWN (Sum- Product Algorithm over a Wireless Network) was shown to provide accurate position estimate even in challenged indoor environments, thanks to exchange of local information among peers. In this paper we extend...
The rate optimization for wireless networks with low SNR is investigated. While the capacity in the limit of disappearing SNR is known to be linear for fading and non-fading channels, we study the problem of operating in low SNR wireless network with given node locations that use network coding over flows. The model we develop for low SNR Gaussian broadcast channel and multiple access channel respectively...
The reliable broadcast and multicast lifetime maximization problems in energy-constrained wireless ad-hoc networks are considered in this paper. In packet loss-free networks, the optimal solution of lifetime maximization problem can be easily obtained by tree based algorithms. In unreliable networks, we formulate them as min-max tree problems. A link quality-aware heuristic algorithm called MLRBT...
Successive interference cancellation (SIC) is an effective way of multipacket reception to combat interference. We study link scheduling under SINR (Signal to Interference Noise Ratio) model in ad hoc networks with SIC at physical layer. The facts that interference is accumulated and the links decoded sequentially by SIC are correlated pose key technical challenges. We propose conflict set graph (CSG)...
In this paper, we study the problem of transmission power control and its effects on the link-scheduling performance when a set of end-to-end flows established in the network are given. This problem is approached by means of the stability region of the link-scheduling policy. The stability region is defined for link-scheduling policies as the set of input-packet rates under which the queues in the...
To support seamless communications for roaming users over heterogeneous wireless networks, mobile ad-hoc networks (MANETs) are receiving a special interest in the research community due to its infrastructure-less nature. MANETs can help to achieve a seamless service for users roaming over areas with no coverage from other wireless networks. As a result, MANETs are a key access network component of...
In this paper, we investigate the convergence behavior of the primal-dual scaled gradient algorithm (PDSGA) for solving distributed network utility maximization problems under time-varying fading channels. Our analysis shows that the proposed PDSGA converges to a limit region rather than a point under FSMC channels. We also show that the asymptotic tracking errors are given by O(T̅/N̅), where T̅ and...
Employing channel state information at the network layer, an effective routing metric is obtained that minimizes the end-to-end outage probability in amplify-and-forward multihop wireless networks. A disadvantage of the routing metric obtained is that it cannot be optimized in distributed manner, i.e., it does not converge onto optimal routes. The disadvantage cannot be remedied by exhaustive search...
The existing credit-based mechanisms mainly focus on stimulating the rational packet droppers to relay other nodes' packets, but they cannot identify the irrational packet droppers such as compromised or broken nodes, which has negative impact on the network performance. In this paper, we propose a credit-based mechanism that uses credits to stimulate the rational packet droppers to cooperate, and...
When asymmetric cryptography techniques are used in wireless networks, the public keys of the nodes need to be widely available and signed by a Certificate Authority (CA). However, the existence of a single CA in large wireless networks such as mobile ad hoc networks and wireless sensor networks can lead the hotspot problem and become a security weakness. In this work, we propose a distributed technique...
In this paper, we study the transition phase in the network connectivity. We focus on the critical time points that mark the network transformation from partition to connected state following a growth of node density. The percolation theory is used to analyze the relationship between the density increase process and the connectivity transition. Specifically, we derive the lower bound and the upper...
Cooperative Peer-to-Peer (P2P) information repair has been proposed to mitigate the packet loss among mobile peers during the 3G Cellular Base Station (BS) broadcast. Then network coding based P2P information exchange algorithms have been proposed to further improve the network performance, e.g., PIE algorithm and DNC-CPR algorithm. In this paper, we propose a connected dominating set (CDS) based...
Cognitive radios (CR) and cooperative communications represent new paradigms that both can effectively improve the spectrum efficiency of future wireless networks. In this paper, we investigate the problem of cooperative relay in CR networks for further improved network performance. The objective is to provide an analysis for the comparison of two representative cooperative relay strategies, decode...
Opportunistic Routing (OR) has recently been proposed to improve the efficiency of unicast in multi-hop wireless networks. OR exploits the broadcast nature of wireless transmission medium and opportunistically selects a relay path to deliver a packet to its receiver. To adopt OR in wireless multicast, the main challenge is to efficiently share opportunistic relay paths between multiple receivers....
This paper focuses on the security problem in unreliable wireless ad hoc networks when involving network coding. A typical example of misbehaviors by bad nodes is presented to show the misbehavior propagation problem of network coding. To reduce the influence of bad nodes, we propose to combine network coding with trust scheme. In our trusted network coding, a trust model is established according...
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