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This paper proposes a cooperative multiple relay transmission scheme for broadband wireless mesh networks in which the number of hops is limited to two. In the proposed scheme, a source node multicasts a signal to some relay nodes that locate sufficiently close to the source node. Then each relay node simultaneously transfers a different part of spectrum in a cooperative manner. Because only a part...
We analyze the gain in network connectivity that is obtained by implementing multiple radio interfaces in the nodes. The multi-radio nodes can act as if the network had effectively multiple physical layers. We model such a network topology by a multigraph and capture the gain by introducing the novel graph theoretic concept of the multigraph advantage. When applied to connectivity, it is the surplus...
We consider a spectrum sharing protocol in which a secondary system operates on the same spectrum as a primary system, without adversely affecting the rate of the primary system. The protocol comprises of a two-phase transmission. In the first phase, the primary transmitter transmits a primary signal to the primary receiver, which is also received at the secondary transmitter and receiver. The secondary...
We address the problem of radio resource allocation in the Downlink (DL) of a cellular system with multiple Relay Stations (RS), based on Orthogonal Frequency Division Multiple Access (OFDMA) transmission technology. The design of efficient resource allocation algorithms for such a system is crucial, in order to exploit the potential capacity and coverage increase offered by the relays. We propose...
A fair distributed channel, route, and power control algorithm for multi-hop radio networks is proposed in the present paper. Since adaptive channel and route control algorithms that maximize the total throughput allocate more resources to links with good quality, there will be a large difference in throughput among communication links, and thus these algorithms are not necessarily fair. In order...
The introduction of relaying into wireless communication system for coverage enhancement can cause severe decrease of spectral efficiency due to the requirement on extra radio resource. In this paper, we propose a method to increase spectral efficiency in such a wireless relay network by employing an interference cancellation technique. We focus on a typical scenario of relaying in a cellular system,...
Efficient bi-directional multi-hop wireless networks based on MIMO algorithm or network coding have been proposed in recent literatures. In this paper, a new technique named as MIMO network coding, that is a combination of network coding and MIMO algorithm, will be proposed. By using MIMO network coding, co-channel interference cancellation and efficient bi-directional transmission can be realized...
This paper proposes enabling technologies and strategies for radio resource management (RRM) in decentralized heterogeneous wireless networks. To cope with dynamic variation of user signals' bandwidth in the decentralized RRM, dynamic spectrum control (DSC) is applied to flexibly utilize spot-wise available spectra. Spectrum clipping is further applied as a bandwidth adjustment technique to fit the...
To cope with limited spectrum resources, inefficient spectrum usage and overcrowded wireless communication, the Federal Communications Commission's (FCC) has introduced a new way to manage RF resources: the interference temperature model. With this model the key point is to let unlicensed users use licensed frequencies, provided they can quantify and bound their interference toward the primary license...
Practical implementation of video compression for distributed sources is currently an active research area. The distributed compression paradigm based on the Slepian-Wolf model has been proposed for low-complexity video compression algorithms and energy efficient wireless sensor networks. In this paper, we consider a joint source-channel resource allocation for sensor network applications based on...
This paper analyzes the outage performance of cooperative protocols for the two-way relaying model in which a halfduplex relay assists in the bi-directional communications of two terminals. We first define the outage events of conventional nonadaptive Amplify-and-Forward (AF) and Decode-and-Forward (DF) two-way relaying protocols and derive closed form results for their respective outage probabilities...
This paper studies interference channels with security constraints. The existence of an external eavesdropper in a two-user interference channel is assumed, where the network users would like to secure their messages from the external eavesdropper. The cooperative binning and channel prefixing scheme is proposed for this system model which allows users to cooperatively add randomness to the channel...
In mobile communication environments, traditional routing protocols designed for static wireless sensor networks may fail to deliver data timely. The aim of this work is to identify improvements that can be obtained considering mobility and to recognize its research challenges. We briefly describe different levels of mobility in wireless sensor networks (WSNs) and highlight the efficiency of routing...
Interference and delay are considered as the main reasons limiting the capacity and increasing the new call blocking probability in the cellular systems. The Probability of handover failure is considered a common criterion for performance evaluation of handovers in cellular systems. In this paper we discuss and analyze cognitive radio handover managements based on social agent technology in cellular...
In delay- and disruption-tolerant wireless communication networks, capacity is commonly traded off for delay. That is the case of spatial intermittent connectivity (SIC) networks. SIC networks are designed to provide high data rates to mobile nodes in small disjoint geographical areas. However, because of userspsila mobility, these high data rates come at the expense of significant connectivity delay...
This paper derives an exact closed-form expression for the phase-envelope joint distribution of the kappa-mu fading environment, a general fading model that includes the Rice and the Nakagami-m models as special cases. The derived joint statistics are obtained so that compatibility with both Rice as well as Nakagami-m cases are kept. Monte Carlo simulations are used to validade the formulations.
In this paper, we analyze the capacity of orthogonal frequency division multiplexing (OFDM) systems with carrier frequency offset (CFO) in frequency-selective Nakagami-m fading channels. Previous work on this topic has not taken into account the frequency selectivity of the channel. In this work, we have explicitly attributed the effect of channel frequency selectivity, i.e. frequency domain correlations,...
This paper describes an energy-efficient BOP-based beacon transmission scheduling (EBBS) algorithm. EBBS is the centralized approach, in which a resource-sufficient node called as Topology Management Center (TMC) allocates the time slots to transmit a beacon frame to the nodes and manages the active/sleep schedules of them. We also propose EBBS with Adaptive BOPL (EBBS-AB), to adjust the duration...
Currently a number of 802.11 based standards support multiple rates at physical layer and recently 802.11 MAC protocols have been modified to make use of these multiple rates. Two such mechanisms, opportunistic auto rate (OAR) and receiver based auto rate (RBAR) have shown to improve throughput performance of wireless LANs as well as infrastructure-less wireless networks. However these protocols are...
Seamless IP mobility protocols like Fast Mobile IPv6 (FMIPv6) requires the knowledge of candidate access routers, to which the mobile node will hand over its connection to, well in advance while the mobile node is still connected to its current AR. The candidate access router discovery (CARD) protocol is one such protocol that provides the identity and capabilities information of the candidate access...
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