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We study the definition of exclusion region through handshake control bursts. The RTS/CTS (request to send/clear to send) bursts that typically take part in the handshake between the radio transmitter and receiver are a perfect medium for sounding their surroundings. Therefore, they can be utilized for setting exclusion regions - geographical areas protecting the active receivers from interference...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) systems aim to reduce the utilized spectrum by multiplexing non-orthogonal overlapped carriers. Since the per carrier transmission rate is maintained, SEFDM yields higher spectral efficiency relative to an equivalent Orthogonal Frequency Division Multiplexing (OFDM) system. Yet, due to the loss of the orthogonality, detection of the SEFDM...
We consider a two user discrete memoryless broadcast channel (DMBC) with perfect feedback from both the receivers. The best known achievable region for the general DMBC without feedback is known as the Marton's region, where the achievable strategy employs random coding. By effectively using the available feedback, we construct explicit coding schemes which achieve any rate-pair in the Marton's region.
In this paper, an adaptive limited feedback linear precoding technique for temporally correlated multiple-input multiple-output (MIMO) channels is proposed, where the receiver has perfect channel knowledge but the transmitter only receives a quantized channel direction. To perform adaptation to the time correlation structure, we employ a differential feedback, where the "amount" of the perturbation...
In this paper we consider a class of degraded relay networks with multiple receivers, address the capacity region for the multicast case, and consider information-theoretic security aspects. Exemplary, we study a degraded relay network, which is comprised of one source, an arbitrary number of relay nodes, and two receiver nodes in a degraded setting. Based on a simple combination of superposition...
In a multiple-input multiple-output (MIMO) precoding system based on finite-rate feedback, the receiver sends a precoding matrix to the transmitter via a feedback channel. The overall system performance is degraded due to feedback error. In this paper, we propose a robust feedback scheme that employs the index permutation technique to provide the system with redundancy-free protection against the...
In order to efficiently use the common channel resources in multi-user multiple-input and multiple-output (MIMO) systems, an independent component based multiple access (ICMA) scheme is introduced. In ICMA, the signals generated by different users are distinguished only from their independence, where neither non-interfering subchannels nor orthogonality constraints are needed. The scheme is based...
A differential cross-correlation cell ID identification algorithm is proposed for IEEE 802.16e OFDMA cellular system. First, we construct the downlink (DL) preamble structure and signal model with carrier frequency offset (CFO) and channel effects. Next, in order to achieve the initial synchronization, a differential receiver with cross correlation for all preamble patterns is proposed to search cell...
In this paper we analyze the performance of random beamforming schemes in a multi-user Gaussian broadcast channel. Each user will have N > 1 receive antennas allowing optimal combining to be performed. To notify the transmitter of its current channel state, each user feeds back their SINR after LMMSE combining. Two feedback schemes are analyzed. The first scheme allows each user to feedback the...
This paper considers the design and analysis of a filter at the receiver of a source coding system to mitigate the excess distortion caused due to channel errors. The index output by the source encoder is sent over a fading discrete binary symmetric channel and the possibly incorrect received index is mapped to the corresponding codeword by a Vector Quantization (VQ) decoder at the receiver. The output...
Opportunistic interference alignment (OIA) and interference subspace projection techniques developed for cognitive radio networks (CRN) works when the transmitters have the perfect knowledge of the channels, which is quite unrealistic in real-time. In this paper, we investigate limited feedback precoding schemes for CRN with a primary and a cognitive MIMO links. Based on the precoding scheme used...
In OFDMA multiple access wireless communication systems, carrier frequency offsets between the transmitter and the receiver tend to destroy the orthogonality among subcarriers, and hence, introduces intercarrier interference. A two-stage frequency offset estimation algorithm based on subspace processing is proposed. The main advantage of the proposed method is that it can obtain the CFOs of all users...
In this paper, we introduce the three-user cognitive radio channels with asymmetric transmitter cooperation, and derive achievable rate regions under several scenarios depending on the type of cooperation and decoding capability at the receivers. Two of the most natural cooperation mechanisms for the three-user channel are considered here: cumulative message sharing (CMS) and primary-only message...
In this paper we propose a novel switched interleaving algorithm based on limited feedback for downlink DS-CDMA systems. The proposed switched chip-interleaving DS-CDMA scheme requires the cooperation among the transmitter, the receiver and a feedback channel sending the index of the interleaver to be used. The transmit chip-inter leaver is chosen by the receiver from a codebook of interleaving matrices...
In this paper, an achievable rate region for the three-user discrete memoryless interference channel with asymmetric transmitter cooperation is derived. The three-user channel facilitates different ways of message sharing between the transmitters. We introduce a manner of noncausal (genie aided) unidirectional message-sharing, which we term cumulative message sharing. We consider receivers with predetermined...
In this paper, we propose a new achievable rate for two-level relay networks by introducing a new strategy named simultaneous partial and backward decoding. In the proposed method, benefitting from regular encoding/backward decoding strategy, different message parts transmitted in the network are simultaneously decoded at the relays and the receiver. The proposed strategy is shown to achieve better...
While the conventional codebook is defined only for the initial transmission in the closed-loop MIMO system, this paper proposes a new retransmission structure with a sequence of multiple codebooks, rather than using a single identical codebook for every retransmission. The pre-coding matrices, in each codebook, are sequentially linked so that each one can be used for a sequential hybrid ARQ transmission...
We consider a compressive wide-band spectrum sensing scheme for cognitive radio networks. Each cognitive radio (CR) sensing receiver transforms the received analog signal from the licensed system in to a digital signal using an analog-to-information converter. The autocorrelation of the compressed signal is then collected from each CR at a fusion center. A compressive sampling recovery algorithm that...
In this paper, we propose a new data receiver mechanism on broadcast environment such that allow mobile clients to determine the time interval of active and sleep mode for connection according to turnaround time. We develop a benefit-oriented data retrieve protocol that allows mobile users to acquire more valuable data with little power consumption within a limited turnaround time. Our performance...
When the GPS signal pass through the ionosphere irregularities effect to rapid fluctuation of signal or scintillation occurred. This effect to the GPS receiver position error. This paper presents the error reduction of GPS receiver due to ionosphere irregularities by artificial neural network. The GPS position error depends on the strength of scintillation which measured in scintillation index or...
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