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MAC layer duty-cycling is widely used to reduce idling listening, which is energy-intensive in wireless sensor networks. Among duty-cycling MAC protocols, asynchronous protocols generally have higher energy-efficiency and lower packet latency than synchronized ones. In this paper, we propose a Markov model to analyze the throughput of X-MAC, an asynchronous duty-cycled MAC protocol for wireless sensor...
For wireless LANs, such as IEEE 802.11 networks, the channel utilization efficiency, the system stability, and the fairness of bandwidth allocation are three important criteria for designing medium access control (MAC) protocols. This paper aims to design a simple access mechanism optimized for all the aforementioned issues from a game theoretic perspective. In particular, this paper enables nodes...
Traditional contention-based random-access wireless MAC protocols such as IEEE 802.11 DCF are designed for single-hop wireless networks and do not perform well in multi-hop scenarios due to inefficiency in their medium reservation mechanisms. In this paper, we introduce a new MAC protocol, called EMAC, which improves the efficiency of wireless medium reservation for general asynchronous multi-hop...
In this paper, we consider the coordinated spectrum access problem in a multiuser single-transceiver cognitive radio network (CRN). Our objective is to maximize the sum-rate achieved by all contending cognitive radio users with respect to both spectrum assignment and transmission rate. The problem is posed as a rate-maximization problem subject to hardware and interference constraints. Specifically,...
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...
Several underwater network characteristics, including long propagation delays and a bandwidth dependent on distance, provide unique challenges to protocol designers. In this paper we present STUMP-WR, a distributed routing and channel scheduling protocol, designed for heavily loaded underwater networks. STUMP-WR selects and schedules links using a distributed algorithm to overlap communications by...
Random access is critical to OFDMA wireless networks. However, due to special features of an OFDMA system, how to carry out random access in an efficient manner is still an open issue for OFDMA wireless networks. In this paper, a new random access protocol is proposed for OFDMA wireless networks. It is distinguished by a novel mechanism called concurrent multi-channel carrier sense multiple access...
We describe a methodology that incorporates the impact of control information transfer into MAC protocol optimization. We apply this methodology to the problem of a synchronous broadcast MAC channel, to generate the optimal protocol when the objective function is the average network throughput per slot. We describe a recursive procedure for the symbolic generation of the optimization program for any...
We consider a wireless multi-hop network with sources that are Poisson distributed and relays which are placed on the source-destination line. Given a combined TDMA/ALOHA MAC protocol, we explore the following question of optimal spatial reuse: Increasing the number of nodes that are simultaneously scheduled to transmit in a route allows nodes to transmit more often. At the same time, it results in...
This article presents a new MAC layer protocol for IEEE 802.11 EDCA-based ad-hoc networks with hidden nodes. The key idea of the proposed solution is based on an intelligent two-step reservation procedure which is combined with the advantages of EDCA service differentiation. The new protocol achieves significant performance improvement for high priority traffic (e.g., Voice) in terms of fairness,...
In this paper, we present and evaluate a cross-layer protocol that integrates opportunistic routing into a CSMA wireless mesh network. We develop a MAC model and protocol with enhanced spatial reuse that enables spatial efficient anycast transmissions with more realistic assumptions about the carrier sensing capabilities. Using an optimization framework, we derive a cross-layer algorithm that solves...
The cognitive cooperative system with coexisting scenario of multiple primary users and one secondary capable of relaying is considered. The primary users transmit packets in orthogonal sub-channels. According to the cognitive principle, the secondary activity cannot interfere with the primary performance. Therefore, in this paper, the secondary user makes use of the spectrum when sensed idle. Based...
The paper analysed MAC protocol based on multiple-channel RMA by dividing transmission time of information packet into 1 & a. The paper adopts a joint-control strategy that detect with probability p1 in time 1, detect with probability p2 in time a. On this basis the paper brought forward a new RMA and wireless sensor networks MAC protocol. The paper resolves the throughput of the system, of the...
In this paper, we study two fundamental issues of cooperative communications in distributed wireless networks, namely when to cooperate and whom to cooperate with. In specific, we focus on cross-layer medium access control (MAC) protocol design with beneficial node cooperation. To increase long-term network throughput, we propose an optimal grouping strategy for relay node selection, and devise a...
Contention resolution diversity slotted ALOHA is a simple but effective improvement of slotted ALOHA. It relies on MAC bursts repetition and on interference cancellation to increase the throughput of a classic slotted ALOHA access scheme. This improvement permits to achieve a throughput up to T ≃ 0.55, whereas slotted ALOHA is capable of providing T ≃ 0.37. In this paper we show that the iterative...
This paper proposes a new Random Channel Selection scheme with probabilistic backoff, called RCS, for a class of multi-channel MAC protocols in heavy loads WSNs to tackle the channel conflict problem. By adopting RCS, a node can reduce the probability of selecting a busy channel for data communication. Therefore, RCS can avoid data packet collision, and thus conserve more energy to extend the lifetime...
This paper investigates open vs. closed access in the uplink of femtocell networks, for the particular case of orthogonal multiple access protocols like TDMA or OFDMA. Open access reduces near-far interference and provides an inexpensive way to expand the capacity of the operator's network. Additionally, with a cap on the amount of resources allocated to the cellular users, open access ensures the...
We consider the problem of selfish misbehavior in scheduling algorithms of wireless networks. All wireless scheduling algorithms are designed under the assumption that network users will follow the algorithm specifications. In this paper, we study two scheduling algorithms in which a selfish user might misbehave in order to achieve better performance. In the first case, we consider a network that...
The Web Services Challenge (WSC) is a forum where academic and industry researchers can share experiences of developing tools that automate the integration of web services. In the sixth year (i.e. WSC-10) of the Web Services Challenge, software platforms will extend their solutions to the several composition challenges. Again this year, requests and results will be transmitted within SOAP messages...
Relaying is a well known technique to extend coverage and improve conditions for nodes in the outer coverage region. In this paper we propose a relaying scheme that exploits the spatial separation of relay and destination pairs to improve throughput by allowing simultaneous transmissions. The proposed scheme is a cross-layer optimization for two-hop relaying that uses position information to jointly...
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