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In this paper, we propose a distributed angle estimation method for wireless sensor network localization with multipath fading. The multiple antenna system is equipped at the anchor and the angle of departure (AOD) can be estimated individually at each sensor node with single antenna system. Further, we exploit the space diversity to improve the estimation performance by deploying multiple parallel...
The capacity of a network in which a multiple access channel (MAC) generates interference to a single-user channel is studied. An achievable rate region based on superposition coding and joint decoding is established for the discrete case. If the interference is strong, the capacity region is obtained for both the discrete memoryless channel and Gaussian channel. A boundary point of the capacity region...
This papers considers the downlink of a wireless multicell downlink orthogonal frequency division multiple-access (OFDMA) system where neighboring base-stations (BSs) can jointly encode and transmit data signals to their users using zero-forcing (ZF) precoding in each frequency tone, but only a limited backhaul-capacity is available for each BS to share its user's data streams with the neighboring...
In this work, we propose a cognitive interference management scheme for heterogeneous cellular wireless networks (LTE-A and WiMAX) with macrocells and femtocells (that operate in a closed-access mode). The scheme presented allocates resources (in time and frequency) and transmission opportunities to the macro/femtocells in the network by considering their potential to cause interference at each others'...
In this paper, an efficient rate allocation scheme to maximize the throughput in uplink multi-rate time-hopping ultra-wideband (TH-UWB) communications is proposed. This is a challenging task due to the lack of a suitable closed form expression of the multiuser interference in a multi-rate context. Moreover, an exhaustive search for the optimal solution would be too prohibitive due to the high complexity...
Conventional distributed power control algorithms in cognitive radio networks are based on the assumption of perfect channel state information (CSI) which may lead to performance degradation in practical systems. In this paper, we investigate the robust distributed power control problem in cognitive radio networks by considering the uncertainty of channel gains. Our objective is to minimize the total...
Cognitive radios require accurate spectrum sensing decisions to minimize interference both to themselves and to primary and/or other secondary spectrum users. In dynamic spectrum environments, where interference may appear or disappear on any channel at any time instant, robust spectrum sensing is challenging particularly if only blind methods are available. Blind sensing methods for single spectrum...
In this paper, we evaluate the impact of a mix of co-channel MIMO interferers on the performance of Alamouti Coding in the downlink of a cellular-like system. In particular, taking into account the effects of both path-loss and Rayleigh fading, we derive closed-form expressions for the probability density functions of the resulting signal-to-interference ratios. Simulation results verify the validity...
Applying statistical physics, we study the degree distribution of a wireless ad hoc network node sustaining inter-system interference from heterogeneous wireless ad hoc networks. The relationship between the average number of neighbors of a wireless network node and the number of retransmissions of its message is clarified under different broadcasting schemes. The degree distribution is then generalized...
The problem of optimal resource allocation to share high-quality multimedia content in cognitive ad hoc networks with cooperative relays is addressed in this paper. Cooperative transmission is a promising technique to increase the capacity of wireless links by exploiting spatial diversity without multiple antennas at each node. However, mainstream research in this field focuses on optimizing physical...
Cooperative communication has been proposed as a means to increase the capacity of a wireless link by mitigating the path-loss, fading and shadowing effects of radio propagation. In this paper, we evaluate the efficiency of cooperative communication in large scale wireless networks under interference from simultaneous transmissions. Specifically, we consider tunable spatial reuse time division multiplexing...
We investigate the outage probability and the average bit error rate (BER) of a dual-hop fixed gain relaying system in the presence of co-channel interference and thermal noise at the relay and the destination. Our analysis assumes Rayleigh fading for the source-relay and relay-destination channels and Rician fading for the interfering channels. We present new closed-form/series expressions for the...
This paper describes the challenges of frequency channel selection for WLANs operating in the TV White Space (TVWS) and proposes a dynamic frequency selection (DFS) technique as a solution. Based on the statistics gained from past usage experience of channels, of the TVWS channels' vacancies and channel occupation by the adjacent WLANs, each WLAN evaluates and prioritize the channels independently...
In this paper, we consider filter-and-forward beamforming (FF-BF) for two-way relay networks employing single-carrier transmission over frequency-selective channels. In FF-BF, the relay nodes filter the received signal using finite impulse response (FIR) or infinite impulse response (IIR) filters. For the processing at the transceivers, we investigate two different cases: (1) simple slicing without...
This paper proposes a novel load distribution aware soft frequency reuse (LDA-SFR) scheme for inter-cell interference mitigation and performance optimization in next generation wireless networks. Our proposed scheme aims to provide a solution to effectively achieve inter-cell interference mitigation while maintaining high spectrum efficiency to all users in the cell. The proposed scheme consists of...
Downlink coverage issues for macrocellular users (UEs) in a macrocellular network with Closed Subscriber Group (CSG) femtocellular overlay have so far been investigated almost exclusively via simulation. However, consideration of specific scenarios via simulation may not provide general insights applicable to long-term planning for femto-macro deployments. In this paper, we employ general models for...
In this paper, we consider power control as network layer problem in wireless mesh networks. The network connectivity between nodes is determined by their communication range which in turn can be controlled by adjusting the transmit power level. It is generally acknowledged that reducing transmit power levels of nodes to the minimum required to retain connectivity always increases network capacity...
Cognitive radio (CR) networks can re-use the RF spectrum licensed to the primary user (PU) network by carefully controlling the interference to the PUs. However, due to lack of explicit support from the PU system, CR sensing algorithms often face difficulty in acquiring CR-to-PU channels accurately. Moreover, the sensing algorithms cannot detect silent PU receivers, which nevertheless have to be protected...
We consider a cognitive radio network where primary users (PUs) and secondary users (SUs) coexist and share the same spectrum. Secondary users access the spectrum randomly and limit the outage probability experienced by the primaries by controlling their transmission probability and by obeying a primary exclusion region (PER), within which all SUs have to be inactive. We propose a vertical cooperative...
Successive interference cancellation (SIC) is an effective way of multipacket reception to combat interference. We consider the problem of maximizing the number of successful transmissions based on the physical model in wireless networks with SIC at the physical layer. We propose weighted simultaneity graph to characterize the sequential detection nature of SIC and the accumulative effect of multiple...
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