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The disturbance (clutter plus noise and jamming) covariance matrix which plays a central role in radar space time adaptive processing (STAP) should be estimated from sample training observations in practice. Traditional maximum likelihood (ML) estimators lead to degraded false alarm and detection performance in the realistic regime of limited training. Therefore constrained ML estimation has received...
Modern cellular networks need to serve user terminals with large disparities in mobility, which incurs different accuracy of the channel state information for each user. The impact of such heterogeneous mobility on the multi-cell downlink is analyzed in this paper. The base stations serve a multitude of users by coordinated beamforming. We derive deterministic equivalents for the user performance...
This paper develops a general approach to evaluating SINR-based performance metrics like coverage, throughput, or bit error rate. Specifically, we first propose a generalized channel model which accounts for transmit power, power spectral density and carrier frequency. Then we derive a general expression which can be used to compute a large class of performance metrics that are functions of SINR....
Modern concepts for cellular networks, e.g., heterogeneous networks and small cells, increase base station densities to satisfy the capacity demand and, hence, lead to a highly dynamic, interference-limited regime. For instance, base stations can be turned on and off dynamically in order to adapt the energy consumption, and frequency usage, to fluctuating traffic demand. The time scale of such operations...
The great potential of multi-cell processing in Coordinated Multi-point (CoMP) transmission is hindered by the limited bandwidth of the backhaul network. In this paper, we tackle this problem from two perspectives. First, we provide a thorough analytical study of the expected capacity when employing zero forcing (ZF) beamforming based on quantized channel state information (CSI). We derive simple...
To improve the spectral efficiency of amplify-and-forward (AF) half-duplex relaying schemes, we propose a multidestination AF relaying protocol, in which the source sends two different data streams in two time-slots to two destinations with the aid of two relay nodes. In contrast to the conventional singledestination AF relaying protocol, the proposed multi-destination AF relaying protocol allows...
Despite great effort from the research community, wireless networks still operate below full capacity. To increase the network throughput it is important to study algorithms that select communication requests that can decode their signals despite mutual interference. In this paper, we study the joint problem of data rate assignment and link scheduling in the physical interference model. The objective...
In this paper, we analyze the performance of two-way relaying (TWR) protocol in Rayleigh fading channels, where the terminals and relay are interfered by a finite number of co-channel interferers. The relay is assumed to operate in the decode-and-forward mode. The average symbol error rate (SER) performance for binary phase shift keying (BPSK) is analyzed. To make the analysis mathematically tractable,...
Device-to-device (D2D) communication has seen as a major technology to overcome the imminent wireless capacity crunch and to enable new application services. In this paper, we propose a social-aware approach for optimizing D2D communication by exploiting two layers: the social network and the physical wireless layers. First we formulate the physical layer D2D network according to users' encounter...
This paper investigates the optimal relay beamforming matrix design problem in amplify-and-forward (AF) based multiuser two-way relay channels (TWRC). A unified framework is proposed for beamforming designs for various design criteria. The core of our framework is the solution to the classic max-min signal-to-interference-plus-noise ratio (SINR) problem for multiuser TWRCs. Treated as a max-min fractional...
Multi-tier architecture improves the spatial reuse of radio spectrum in cellular networks, and user classification allows consideration for diverse user service requirements. But they introduce complicated heterogeneity in the spatial distribution of transmitters, which brings to new challenges in interference analysis. In this work, we present a stochastic geometric model to evaluate the uplink interference...
A monotonic optimization approach to downlink beamforming is developed to maximize the weighted sum of user rates. After formulating the problem as a monotonic program (MP), a polyblock outer approximation algorithm is devised to construct a nested sequence of polyblocks, and search for the optimal MP solution among the vertices of these polyblocks. In the downlink beamforming context, construction...
CSMA (Carrier Sense Multiple Access), which resolves contentions over wireless networks in a fully distributed fashion, has recently gained a lot of attentions since it has been proved that appropriate control of CSMA parameters guarantees optimality in terms of system-wide utility. Most algorithms rely on the popular MCMC (Markov Chain Monte Carlo) technique, which enables one to find optimal CSMA...
For realizing convincing daily shopping, collecting useful market information is very important. Generally, useful market information for shopper relies heavily on time and place in addition to the person's interest. Then, we have considered a new SNS sharing useful market information among shoppers by using smart phone. In this paper, we report an overview of proposed SNS and propose its new communication...
Current wireless networks are becoming increasingly heterogeneous both in terms of the radio access technologies (RATs) and the base station capabilities. Downlink rate or throughput in such heterogeneous networks is a crucial metric and has been primarily studied using system level simulations. To derive the distribution of rate analytically we develop a fairly general tractable model that consists...
In cellular networks, all base stations (BSs) do not continuously transmit i.e., the BSs transmit only when their queues are non-empty. This implies that the system resources are only partially loaded, and the dynamics of such a network differs significantly from that of a fully-loaded system. The coverage probability in a fully- and partially-loaded cellular network is analysed. We consider a regular...
This paper proposes a coverage-oriented femtocell network deployment scheme, in which the femtocell base stations (BSs) can decide whether to be active or inactive depending on their distances from the macrocell BSs. Specifically, as the areas close to the macrocell BSs already have satisfactory cellular coverage, the femtocell BSs located inside such areas are kept to be inactive. Thus, all the active...
Cooperative relaying achieves a wide range of advantages including diversity gain, coverage extension and mitigation of shadowing. Nevertheless, the performance advantages of cooperative relaying diminish considerably if co-channel interference is present. Optimum combining (OC) can be used to mitigate the adverse effects of co-channel interference in wireless communications. The performance of optimum...
This paper studies the opportunistic spectrum access (OSA) of secondary users in a large-scale overlay cognitive radio network. Particularly, a threshold-based protocol is investigated, where the secondary transmitter is allowed to access the spectrum only if the maximum signal power of the received beacons transmitted by the primary receivers is lower than a certain threshold. To measure the resulting...
Broadcast is a fundamental operation in wireless networks and is well supported by the wireless channel. However, the interference resulting from a node's transmission pose a key challenge to the design of any broadcast algorithms/protocols. In particular, it is well known that a node's interference range is much larger than its transmission range and thus limits the number of transmitting and receiving...
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