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In this contribution, we focus on a frequency domain two-user Multiple-Input-Single-Output Broadcast Channel (MISO BC) where the transmitter has imperfect and (un)matched Channel State Information (CSI) of the two users in two subbands. We provide an upper-bound to the Degrees-of-Freedom (DoF) region, which is tight compared to the state of the art. By decomposing the subbands into subchannels according...
In this paper, we propose a method to find an optimal correction value for multiple carrier frequency offsets (CFO) compensation, where two received signals have different path gains, in orthogonal frequency division multiplexing (OFDM) systems. Multiple CFOs are occurred when two spatially-separated transmitters are used to transmit the same signal simultaneously. In this case, the sidelobes of the...
A 2×2 60 GHz MIMO solution combined with polarisation diversity is proposed for high throughput WLAN applications. In addition to a PHY throughput of more than 12 Gbps, this scheme is robust against polarisation mismatch and antenna tilting due to the adoption of circular polarisation. It also offers the possibility to detect LOS/NLOS conditions for antenna adaptation. A fast beamforming ability that...
In this paper, a ray-tracing technique taking into consideration the effects of user-body shadowing is investigated. With the rapid growth in the applicability of mobile devices, accurate received signal predictions are increasingly important. The user's body especially has a great impact on the received signals, because it is nearly always located close to the mobile device. We consider two deterministic...
In this paper, we present a wideband single-input single-output (SISO) car-to-car (C2C) channel model based on a geometrical semicircular tunnel (SCT) scattering model. Starting from the geometrical scattering model, a reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS) and non-LOS (NLOS) propagation environments. In the proposed channel model,...
Localization of Wireless Capsule Endoscope (WCE) inside the small intestine is a very challenging problem, which is very important for the diagnosis of certain diseases. Previous studies have shown that Time-of-Arrival (TOA) localization can be more effective than Received Signal Strength (RSS) based localization. Performance evaluation of TOA-based localization techniques for WCE requires understanding...
Applications based on precise indoor and urban area localization are becoming quite popular. The integration of localization in currently existing wireless data communication systems is especially interesting. The popularity comes from the possibility to economically use the same analog front-end for data communication and localization. In indoor environments, where the precision should be under 1...
This paper investigates the optimal resource allocation for a Gaussian multiple access channel (MAC) with two transmitters powered by a shared energy harvester. A deterministic energy-harvesting (EH) model is adopted, which assumes that the energy arrival amounts and timing are non-causally known before transmissions. Besides, packets for both transmitters are assumed always ready before transmissions...
In this paper, we study the effects of finite size resources in point-to-point energy harvesting wireless networks. We consider a transmitter and a receiver with finite size buffers and batteries, both powered by energy harvesters. We use a discrete-time analysis technique to study total packet loss at the transmitter and receiver when both are constrained by finite resources. We show how resources...
The direct-conversion architecture used for Orthogonal Frequency Division Multiplexing (OFDM) systems suffers from intercarrier interference (ICI) between image subcarriers in each OFDM symbol due to I/Q imbalance between the inphase (I) and quadrature (Q) branches at the transmit and receive sides. One of the widely-used metrics to evaluate the performance degradation due to I/Q imbalance is the...
Due to the broadcasting nature of wireless transmission, the cochannel interference in heterogeneous networks among the cells can be a potential limiting factor in cellular systems. To overcome this limitation, many interference mitigation techniques for femto-cells have been proposed, which mainly focus on power control and spectrum allocation. In this paper, through the technique of dirty-paper...
When energy is harnessed by wireless nodes from renewable sources, its availability becomes uncertain and its use for communications must be carefully designed. While the optimal power allocation has been derived in previous works when energy availability is fully (a priori) known, practical algorithms are needed when only causal and statistical information is available. In this paper, we study the...
Beamspace MIMO (BS-MIMO) is a newly proposed transmission technique that can successfully overcome the two significant disadvantages of conventional MIMO. More specifically, BS-MIMO using Electronically Steerable Passive Array Radiators (ESPAR) achieves similar multiplexing and beamforming capabilities using a single RF chain. Moreover, it is proved that BS-MIMO benefits from the use of small sized...
We consider the two-user time correlated multiple-antenna interference channel (IC) under realistic conditions. Specifically, the transmitters have not only perfect delayed channel state information (CSIT), but also asymmetrically imperfect current CSIT. Delayed CSIT, met to cases of practical interest (certain feedback latency and limited quality), can still be useful as shown by Maddah-Ali and Tse...
Interference alignment (IA) is a promising technique to achieve more than one degree of freedom in wireless interference networks. It has been shown that in a k-user multiple-input multiple-output (MIMO) interference channel where each N-antenna transmitter communicates with its intended M-antenna receiver by sending d independent data streams, the aggregate number of transmit and receive antennas...
This paper addresses the problem of decoding and precoding in the K-user MIMO interference channels. At the receiver side, a joint decoding of the interference and the desired signal is able to improve the receive diversity order. At the transmitter side, we introduce a joint linear precoding design that maximizes the joint cut-off rate, known as a tight lower bound on the joint mutual information...
In this work we propose a variation to the Block Diagonalization (BD) algorithm described that mitigates the interference from an external interference source which does not participate in the joint transmission inherent to the BD algorithm. The idea consists of precoding the signal at the transmission side so that the received signal at each receiver lies in a subspace orthogonal to the subspace...
The performance of multiple-input multiple-output (MIMO) systems can be enhanced with the availability of channel direction information at the transmitter. One of the known techniques to feedback channel direction (eigenvector) information is parametrization using Givens rotations, which is also adopted in IEEE 802.11n standard. In temporally correlated MIMO channels, the feedback overhead can be...
We consider the distributed pricing (DP) algorithm for adapting transmit beamforming vectors in a multi-user multiple-input multiple-output interference channel. Our objective is to maximize the sum of all user utilities. Each user announces an interference price which reflects the marginal cost of interference from other users. A particular user then updates its beamforming vector to maximize his...
Base station cooperation is a promising technique to address the serious co-channel interference issue, but dramatic signaling overhead and high computational complexity are inherent in this advanced coordination technology. Limited form of cooperation among base stations becomes an practical method to deploy this multiple cell processing in a realistic network. After analyzing the multi-cell sum...
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