The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Opportunistic relaying has been recently proposed to eliminate the need of symbol synchronization and challenging code design in distributed space-time coded (DSTC) cooperation yet achieving the same diversity multiplexing tradeoff. In opportunistic relaying, the relay terminal that possesses the best relay-destination channel quality is selected by the destination for cooperative forwarding. Combining...
We investigate the incremental relaying protocol in conjunction with relay-selection cooperative diversity networks with an aim to make efficient use of the degrees of freedom of the channels by exploiting a limited feedback signal from the destination. In particular, whenever the direct link from the source to the destination is not favorable to decoding, the destination will request the help from...
We consider the uplink of two mobile stations with the help of one common relay. Recently, joint network-channel coding based on LDPC codes was proposed for this setup where the channel codes at the mobile stations and the network code at the relay form one distributed LDPC code. This approach allows to gain diversity with a higher rate compared to a relay system without network coding. We propose...
In a protocol assisted switched diversity (PASD) system, the time separated repetition blocks are accumulated in order to increase decoding reliability. In this paper, we consider transmit antenna selection (TAS) protocols in a PASD system. To minimize system complexity we assume the feedback information is limited to the SNR of the current pair of antennas. We propose three TAS protocols : the random...
In, the authors have presented a detailed analysis on the problem of distributed space-time coding employing Amplify-and-Forward (AF) protocol for a synchronized wireless relay networks, where maximum likelihood (ML) decoding is employed. In this paper, an iterative turbo-like decoder is introduced to improve system performance by allocating interleavers at each relay node and using multiuser concept...
This paper presents a new cooperative MAC (medium access control) protocol called BRIAF (best relay based incremental amplify-and-forward). The proposed protocol presents two features: on-demand relaying and selection of the best relay terminal. "On-demand relaying" means that a cooperative transmission is implemented between a source terminal and a destination terminal only when the destination...
This paper presents an analysis of cooperative direct-sequence code division multiple access (DS-CDMA) relay communications with one source terminal and two relay nodes with multiuser detection over the frequency-flat fading channel for uplink transmission where the decode-and-forward (DF) protocol is employed at the relay nodes. We analyze for synchronous transmission with binary phase shift keying...
We propose an adaptive space-time block code (A-STBC) for the wireless communication system. A group of minimum-decoding-complexity quasi-orthogonal STBC (MDC-QO-STBC) matrices which are the same size and code rate but different in the performance of combating inter-symbol-interference are obtained, and a specific matrix is selected from the group for a certain channel according to its channel state...
The promise of substantial capacity increase by exploiting spatial diversity has made MIMO systems a new frontier in wireless communication research, but this performance gain is theoretical and does not take real world impairments like channel correlation into account. A lot of work has been done on MIMO detectors. However performance analysis in spatially correlated channels in real world scenarios...
Space-time coded modulation has been shown to efficiently use transmit diversity to increase spectral efficiency. Such high-rate orthogonal designs are available for complex symbol constellations only for two, three, and four transmit antennas. For five and six transmit antennas, two generalized complex orthogonal space-time block codes of rates 7/11 and 3/5 were proposed recently. In this correspondence,...
This paper proposes a novel scheme that combines coded cooperation and truncated ARQ/FEC protocol at the physical and data link layers. Although the coded cooperation method can achieve remarkable diversity gains through independent fading channels, its characters such as bit error rate (BER) and spectrum efficiency are influenced greatly by inter-users' channel qualities. Hence, we introduced the...
Cooperative communication schemes can provide diversity gain. However, when the network model is compose of multiple source-destination pairs with multiple common relays, interference problems arise. In this paper, we propose a cooperative transmission scheme based on Interleave-division multiple-access (IDMA) with decode-and-forward (DF) and amplify-and-forward (AF) protocols so that destinations...
In this paper we evaluate the coded and uncoded performance of a 2-antenna terminal relaying scheme, for downlink OFDM based systems, using efficient space-frequency block coding protocols. We consider that the relay and the base station are equipped with 2 antennas and the user terminal has a single antenna. Two types of relay protocols are accounted for: equalize-and-forward and decode-and-forward...
In this paper, we present a new outage probability analysis of a cooperative system with single antenna terminal. We first introduce the cooperation protocol of the presented scheme. Then, in the destination node, maximal ratio receiver combining (MRRC) and the maximum likelihood (ML) detection algorithm are applied to decode the received signal with the utilization of the signal received from the...
We investigate the symbol error rate (SER) and outage probability of the cooperative transmission with the decode-and-forward relay protocol over dissimilar Rayleigh fading channels. The technique of orthogonal space-time block coding (STBC) is applied at the links of source-relay, source-destination and relay-destination. Closed-form expressions of outage probability and SER are derived, respectively...
We investigate the performance of rateless codes for single-server streaming to diverse users, assuming that diversity in users is present not only because they have different channel conditions, but also because they demand different amounts of information and have different decoding capabilities. The LT encoding scheme is employed. While some users accept output symbols of all degrees and decode...
For multiple amplify-and-forward (AF) relays, optimal decoder and beamforming vector have been presented [3], [4]. The derivations of these optimal ones have been based on the generalized eigenvalue problem. In this work, we show the derivations using the Cauchy-Schwartz inequality. Moreover, the intimate relation between decoder and beamforming vector is analyzed.
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...
A technical consensus for future LTE-advanced 4G systems is the adoption of relay stations (RS) for better link performance. While study in relay systems is often carried out for individual users independently, in this paper, we present a new design termed as relay-based multi-user cooperative communication specifically for the uplink of 4G systems. In this system, data streams from multiple users...
Code diversity integrates space-time coding with beamforming by using a small number of feedback bits to select from a family of space-time codes. Different codes lead to different induced channels at the receiver, where channel state information (CSI) is used to instruct the transmitter how to choose the code. Feedback can be combined with sub-optimal low complexity decoding of the component codes...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.