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Energy efficiency is a considerable criterion in design of wireless sensor networks. MIMO technology has the potential of supporting a higher data rate under a lower power budget and bit-error-rate, which makes cooperative MIMO in WSNs a popular research topic. This paper investigates a cluster-based time division cooperative MIMO communication system for WSNs. An optimum algorithm for the power and...
A (layered) broadcast approach is studied for fading wiretap channels. The basic idea is to employ superposition coding to encode information into a number of layers and use stochastic encoding for each layer to keep the corresponding information secret from an eavesdropper. The legitimate receiver successively decodes information one layer after another by canceling the interference caused by the...
3GPP LTE specification is stable now in release 8. To meet much higher requirements than release 8, 3GPP has initiated the LTE-A (LTE-Advanced) study item. In LTE-A, CoMP (coordinated multiple point transmission and reception) and CA (carrier aggregation) are two new features. CoMP is used to improve coverage and to increase cell-edge throughput. It is considered as an effective approach for ICIC...
The problems of resource allocation and the characterization of cooperative behavior in a two-user fading multiple-access channel (MAC) in the presence of uncertainty about the channel state information at the transmitters (CSIT) are considered. Game-theoretic techniques are used to characterize cooperative behavior and obtain the system operation point from an individualistic perspective. A two-user...
Conflict-free power allocation for secondary user (SU) in cognitive networks is a challenging problem since the accessible spectrum of the SU is shared with the primary user (PU); the problem becomes to be especially difficult when it is wanted to achieve the maximum network capacity considering the mutual interference between PU and SU. In this paper, specifying the single SU case with multiple PUs,...
The fading cognitive multiple-access channel with confidential messages (MAC-CM) is investigated, in which two users attempt to transmit common information to a destination and user 1 also has confidential information intended for the destination. User 1 views user 2 as an eavesdropper and wishes to keep its confidential information as secret as possible from user 2. The multiple-access channel (both...
A new amplify-and-forward (AAF) strategy is proposed for user cooperation channels. Differing from the previously reported ones in which users either send independent signals, i.e., Azarian's AAF, or do not directly send information to the base station, i.e., Laneman's AAF, the proposed AAF strategy allows users to send signals that are correlated with the previously transmitted signals. The achievable...
The achievable transmission rate of the multicast services is in general limited by the worst case mobile users within the multicast service sectors. Yet, unlike relay-assisted unicast service, there is a unique challenge in applying relay to multicast service. To be more specific, the multicast service shall be able to provide a uniform treatment for the mobile users within and without the relay...
In this paper, we investigate the error rate performance of a multi-relay two-way cooperative communication system with amplify-and-forward relaying over Rayleigh fading channels. We derive a closed-form expression for symbol error rate (SER) in terms of finite-range integrals. This is later utilized to optimize power allocation among cooperating terminals. Exploiting the location information of terminals,...
An adaptive resource allocation scheme is proposed for regenerative relay-based orthogonal frequency division multiplexing access systems. This scheme allocates subchannels to guarantee fairness between users, and also saves energy by minimising the transmission power. The subchannel allocation for data rate fairness is considered between direct link users and relay stations in the first time subslot...
We propose a subchannel allocation by considering multiuser diversity to reduce self interference (SI) which arises due to the destrunction of orthogonality of spreading codes in orthogonal frequency division mutiple access - code division multiplexing (OFDMA-CDM) system. The conventional OFDMA-CDM does not effectively reduce SI, since it does not consider multiuser diversity. The proposed scheme...
With the proliferation of wireless multimedia applications, multicast/broadcast has been recognized as an efficient technique to transmit a large volume of data to multiple mobile stations at the same time. In most multicast systems, the transmitter (e.g. base station) adapts its data rate to the furthest located users, so as to guarantee service quality to as many users as possible. Predictably,...
We consider the fading broadcast channel from a secrecy point of view. In this channel, each user views the other user as an eavesdropper, and wants to keep its information as secret from the other user as possible. First, we consider a more general channel model which consists of L independent sub-channels, where in each sub-channel, one of the users' channel is less noisy with respect to the other...
In the broadband mobile service market, it is reasonable that the carrier (service provider) should choose a Pareto-efficient resource allocation policy so that both the revenue of the carrier and the utility of users can be maximized. In this paper, we investigate the fundamental problem of the existence of resource allocation policies that are Pareto-efficient between the revenue and the utility...
We study the problem of jamming in a fixed-rate wireless system over fast fading channels. Both transmitter and jammer are subject to long term (average) power constraints. Our jamming problem is formulated as a zero-sum game, with the probability of outage as pay-off function and power control functions as strategies. We consider both the case with full channel state information (CSI) at all parties...
Based on decode-and-forward strategy, we investigate the achievable outage probability of opportunistic relaying, in which there is a single source-destination transmission pair with the help of one of multiple relays. In two-hop scenario, based on adaptive decode-and forward strategy, the achievable diversity-multiplexing tradeoff with the knowledge of channel state amplitudes is analyzed. We show...
We consider the estimation of a Gaussian source by a Gaussian sensor network where L distributed sensors transmit noisy observations of the source through a Gaussian multiple access channel to a fusion center. In a recent work, Gastpar showed that for a symmetric sensor network with no fading, analog (uncoded) transmission achieves the optimal performance theoretically attainable (OPTA). In this work,...
In this paper, a two-hop amplify-and-forward cooperative diversity system using OFDM modulation was considered. We proposed an associated waterfllling power allocation scheme under separate power constraints at source and relay, which allocated source and relay power in an associated fashion. The scheme first allocated power to subcarriers uniformly, then gave an approximate equivalent channel gain...
In this paper, we study an optimum power allocation problem for expected achievable rate maximization in a typical three node cooperative relay network with slow block fading channels. A long term average power and an outage probability threshold serve as the constraints on the problem. This is motivated by the fact that in many applications, a mixture of delay-sensitive and -insensitive data are...
In this paper, distributed power allocation schemes are studied for amplify-and-forward (AF) cooperative relay networks, where only partial channel state information (CSI) is available at the source and relays. Aiming at minimizing the total transmit power while providing a target outage probability, a scheme is first investigated in which the source decides transmit power and a relay-forwarding threshold,...
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