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The paper aims at considering an alternative structure for transmitter and receiver in OFDM/OQAM systems. Such a structure is based on the frequency spreading at the transmitter and on the frequency despreading at the receiver and it is considered with reference to its implementation complexity. A modified structure is also proposed in order to reduce its computational complexity.
This paper describes the OFDM/QAM and OFDM/OQAM platforms that have been built these last years in Orange Labs in order to compare both modulation schemes. The targeted application was related to the physical layer of mobile terrestrial digital video broadcasting networks; then system parameters are borrowed from the corresponding DVB standards. In addition to a usual evaluation on AWGN channel, SFN...
Characteristic of receiver output SNR associated with Source-to-Relay-to-Destination link for Amplify and forward relaying systems is studied and theoretical expressions for probability density function and cumulative distribution function are derived. Thereby, closed-form solution for outage probability of the system is derived. The analysis is then extended to a scenario where the destination combines...
In this paper, we propose a new transmission scheme with two relay stations and phase feedback channels between the relays and the destination node. The exploiting of a preprocessor use in the relay stations is managed to achieve a full diversity order and also an array gain at the destination node. A phase feedback investigation for the proposed scheme is presented assuming quasi-static flat Rayleigh...
Wireless sensor networks have increasingly been gaining importance because of their applications in many domains, including remote sensing, traffic management, disaster alarm, and anomaly detection. In many of these applications, sensor nodes cooperate in obtaining an estimate of a control or environmental parameter to achieve capabilities that cannot be achieved by letting the nodes work individually...
The Device-to-Device (D2D) communication can increase data rates and resource utilization in cellular networks. However, the direct application of the D2D communication can cause harmful interference to the cellular network. Therein, power control algorithms become essential tools to keep interference controlled and to ensure improved system performance. In this paper, we study two power control strategies...
This paper presents results of the Seventh Framework Programme (FP7) LOLA (achieving LOw LAtency in wireless communications) project about the design of a cooperative broadcast (CB) technique based on a decode and forward (DF) protocol, in the context of a clusterized wireless mesh network (WMN) based on 3GPP LTE PHY/MAC layers. The CB technique is compared to a baseline broadcast technique, obtained...
In this paper, a spatially multiplexed orthogonal frequency division multiplexing multiple input multiple output (SM-OFDM-MIMO) IEEE 802.11n system is assumed. The 802.11n system performance is comparatively analyzed implementing either linear minimum mean squared error (MMSE) receiver or MMSE ordered successive cancellation (MMSE/OSIC) receiver with both hard and soft decision Viterbi decoding over...
In this paper, a two-stage detector is proposed for signals transmitted using multiple antenna configurations over frequency-selective channels. For the first stage, a frequency domain equalizer applying the minimum mean-squared error criterion is used to mitigate the intersymbol interference introduced by the channel's non-flat frequency response. Following, the output of this frequency domain equalizer,...
The coexistence of a single-input single-output (SISO) primary link and a multiple-input single-output (MISO) secondary link is considered in an extended cognitive radio channel setup, where the secondary transmitter has to obtain (“learn”) the primary message in a first phase rather than having non-causal knowledge of it. An achievable rate region is derived that combines decode-and-forward relaying...
Communication between clusters of wireless terminals in an ad hoc network can be initialized using distributed beamforming, where low-power wireless terminals cooperatively form a multiantenna array. Various methods for implementing distributed beamforming in wireless ad hoc networks have been considered before, but little research has been conducted so far in the connection initialization and cluster...
In this paper, we propose and analyse an adaptive algorithm for distributed beamforming in OFDM systems over time and frequency selective channel conditions. We discuss how the key parameters related to convergence speed of the algorithm can be optimized to suit networks with different degrees of transmitter mobility. We show that the proposed adaptive algorithm is beneficial when used in mobile conditions;...
In wireless ad hoc network communications, both the network interference and the thermal noise should be considered in receiver design, due to the strong impairments each may cause on the quality of the reception at the destination. Since the closure under convolution of stable distributions only holds for the same stability index members, in general the additive convolution of impulsive stable interference...
Interference alignment (IA) has been shown to achieve the maximum degrees of freedom in the multiple-input multiple-output (MIMO) K-user interference channel (IFC). In the presence of frequency-selective channels, orthogonal frequency-division multiplexing (OFDM) is typically used to deal with the multipath nature of the channel. While IA techniques can be applied in a per-subcarrier basis (post-FFT),...
A novel interference alignment (IA) algorithm is presented. IA solutions can be obtained in closed-form for special cases only. In general, iterative algorithms need to be used. Most of these algorithms are based on a joint design of precoders at the transmitter side and receive filters at the receiver side, while the proposed method achieves IA with a precoder design only. A design based on precoders...
We consider the maximization of Weighted Sum Rate (WSR) for a Noisy Multiple-Input-Multiple-Output (MIMO) K cell Interfering Broadcast Channel (IBC) when only partial channel state information is available at the transmit side (CSIT) while assuming perfect CSI at the receiver (CSIR). In this work, CSIT is modeled by means of a Gaussian prior representing the mean and the covariance of the channel...
In the context of green technology, we propose in this work1 a new channel access method for wireless systems to reduce energy consumption. This method uses the concept of Cross Layer Design and cognitive radio blind sensing techniques to formulate a unified framework for congestion and fading analysis as well as Backoff exponent computation. It allows to acquire from the physical layer the information...
We propose a MIMO spatial multiplexing system with distributed single-antenna relay stations which operate in the amplify-and-forward mode. A maximum likelihood detector is implemented at the receiver. We evaluate the system bit error rate (BER) performance by means of a semi-analytic bounding method which can closely bound BER at high signal to noise ratio (SNR), and hence determine diversity order...
We consider a Gaussian multiple-access channel (MAC) with an amplify-and-forward (AF) relay, where all nodes except the receiver have multiple antennas and the direct links between transmitters and receivers are neglected. Thus, spatial processing can be applied both at the transmitters and at the relay, which is subject to optimization for increasing the data rates. In general, this optimization...
A new approach of indoor positioning has recently been proposed: the repealite system. It aims at providing a continuity of the positioning service through the use of GNSS (Global Navigation Satellite Systems) signals, thus leading to a single technological mean, the GNSS receiver, for both outdoors and indoors. A few error sources have to be dealt with in order to reach sub-meter accuracy, among...
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