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We consider a system where users aboard communication-enabled vehicles are interested in downloading different contents from Internet-based servers. This scenario captures many of the infotainment services that vehicular communication is envisioned to enable, including news reporting, navigation maps, and software updating, or multimedia file downloading. In this paper, we outline the performance...
A hybrid wireless network combines a mobile ad-hoc network and an infrastructure network. Efficient and reliable data routing is important for high throughput in such networks. Existing routing schemes that simply combine ad-hoc and infrastructure routings inherit the drawbacks of ad-hoc routing and fail to take advantage of the infrastructure for high efficiency. Current reputation systems relying...
Overlay network architectures that use orthogonal channels have been known to provide effective additional resources to underlying networks in high demand. Overlays are composed of relay nodes provided with rich computational resources and multiple wireless interfaces that make them capable of establishing several non-interfering networks. These networks can be used to move traffic around in a non-interfering...
The prime focus of this work is in describing a symbiotic architecture for a Cognitive Radio network, called Cognitive Relaying with Frequency Incentive. The incumbent Primary User (PU) of the spectrum, with a weak transmission link, seeks cooperation from the cognitive Secondary User (SU) nodes in its vicinity, and in return rewards them with incentive frequency bands for their own communication...
In this paper, we study the capacity and delay scaling laws for cognitive radio networks (CRN). The primary network consists of static, randomly and evenly distributed primary users (PUs), which require high throughput with low delay. The secondary network consists of $m=O(n^{1+\delta})$ randomly and evenly distributed cognitive secondary users (SUs) with $\delta>0$, which move in different area...
This paper considers distributed opportunistic scheduling (DOS) with cooperative relaying in wireless ad hoc networks, with a focus on characterizing the desired tradeoff between the probing cost for establishing cooperative relaying and the higher throughput via opportunistic cooperative networking. Specifically, distributed scheduling and probing for cooperative relaying is treated as an optimal...
We consider communication in the uplink of a wireless mesh or sensor network. A group of mobile radios or sensors (hereafter called "nodes") have information to transmit to one or more access points (APs) (or "sinks"). When the channels from the nodes to the APs suffer from fading, direct transmissions to the APs may fail with a high probability, and packets may need to be relayed...
Due to the broadcast nature of wireless transmis- sions, overheard signals can be exploited in multi- hop wireless networks so as to improve the network performance. It has been shown that energy accumulation and information accumulation are two main approaches to utilize multiple overheard signals. However, how to jointly accumulate energy and information in multi-hop wireless networks is still unknown...
Cooperative Network-Coded Hybrid ARQ (Coop-NC HARQ) has recently been proposed as a smart way to improve Decode & Forward (D&F) relaying. According to this idea, cooperators send HARQ redundancy on behalf of a source coded together with a data packet intended for the destination they are helping and taken from their own queue. This paper applies for the first time such a technique in ad hoc...
Relay node (RN) plays a key role in cooperative communications and RN selection may substantially affects the performance gain. In this paper we address the issue of RN selection while taking into account Medium Access Control (MAC) overhead, which is incurred by not only handshake signaling but also frame retransmissions due to transmission error. We use a theoretical model to analyze the cooperation...
This paper analyzes the performance of the Physical Layer Network Coding (PLNC) approach based on Decode-and-Forward (DF) and operating in multipath fading channel. In actual channel affected by multipath fading the DF method has poor performance since the relay node cannot properly perform data decoding. In addition the decoding at the relay requires the knowledge of the channels involved in the...
Delay/Disruption Tolerant Network (DTN) differs from the conventional networks in that it has no continuous or contemporaneous connections among wireless nodes. Its inherent characteristic of intermittent connections makes existing routing solutions hardly to be applied directly. Epidemic routing using random linear network coding has been studied and proved as an efficient way for light data delivery...
The broadcast nature of wireless links makes wireless networks an attractive environment for intersession network coding. Most intersession network coding protocols exploit this property, but ignore the diversity among the links by turning off coding when the channels are lossy. Other protocols deal with the packets separately - not as members of flows - which makes the intersession network coding...
In this paper, we consider a simple network consisting of a source, a half-duplex decode-and- forward relay, and a destination. In contrast to most of the existing literature, we assume that the relay is equipped with a buffer and show that this can lead to substantial performance gains. We propose a simple protocol which chooses either the source-relay or the relay-destination link for transmission...
In this paper, we study the delay/throughput trade-off with opportunistic relaying over channels with random connections, in which the channel connections are independent and identically distributed (i.i.d.). Previous work~\cite{CA:07} which proposed an opportunistic relaying scheme has focused on the throughput analysis only, we show that the opportunistic relaying scheme provides an upper bound...
Supporting real-world activities online has been one of the main goals in applied computer science. However, the gathering of a large crowd for a specific purpose (e.g., lecture, concert, rally), has not yet moved online. The recent concept of crowdcasting (i.e., broadcasting to an audience while engaging them with real-time feedback) may pave the way towards it, but the audience scale and feedback...
We consider the two-way relay channel with random access for the cases of symmetric and asymmetric channel statistics in the low SNR regime. We propose three different schemes implementing different physical layer techniques for collision recovery and channel adaptation and obtain analytical throughput expressions. We compare the proposed schemes with several benchmarks in order to study their bandwidth...
In cognitive radio (CR) networks, cooperative relaying is emerging as a key technology to improve the performance of secondary users (SUs), while ensuring the quality of service of primary transmissions. Most previous work considers maximizing physical layer throughput as a design criterion. However, the end-to-end Transmission Control Protocol (TCP) performance perceived by SUs is largely ignored...
Among the techniques proposed to reduce interference in cellular ODFMA networks, base station cooperation (BSC) is currently the technique known to achieve the highest network throughputs. Its deployment however is vastly expensive and cheaper alternatives are expected to play an important role in future wireless access standards. This contribution introduces relay-augmented networks based on the...
In this paper we introduce a novel Automatic Repeat reQuest (ARQ) scheme for cooperative wireless networks. Our scheme adopts network coding techniques in order to enhance the total bandwidth of the network by minimizing the total number of transmissions. The performance of the proposed approach is evaluated by means of computer simulations and compared to other cooperative schemes, while an analytical...
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