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.
The conventional cooperative protocols have to face some problems in practical broadcast and multicast systems because feedback channel is unavailable. An adaptive cooperative relay protocol, which can be adopted in future broadcast systems, is proposed in this paper. The outage probability performance of this protocol is analyzed over Nakagami-m fading channel, and the asymptotic expression of outage...
We consider the application of switch-and-stay transmit diversity (SSTD) to a three-node cooperative diversity system with decode-and-forward relaying. The basic idea of SSTD generally is to use a certain transmit antenna as long as the induced signal quality satisfies a given requirement while the transmitter switches to another antenna element if this is no longer the case. Applying this principle...
In this paper, we propose an output-threshold multiple relay selection scheme for dual-hop multi-branch cooperative wireless networks. The proposed scheme selects the first Lc arbitrary ordered relays out of L relays such that the maximal ratio combined signal-to-noise-ratio (SNR) of the Lc relayed paths and the direct path barely exceeds a preset threshold. Closed-form expressions are derived for...
In this paper, we have studied the energy efficiency of cooperative networks operating in either the fixed Amplify-and-Forward (AF) or the selective Decode-and-Forward (DF) mode. We consider the optimization of the M-ary quadrature amplitude modulation (MQAM) constellation size to minimize the bit energy consumption under given bit error rate (BER) constraints. In the computation of the energy expenditure,...
In this paper, we investigate the outage performance of Decode-and-Forward with partial selection relaying in dual-hop cooperative Nakagami-m fading links. The source, based on the unique knowledge of local first hop channel state information, selects the best relay to increase the chances of successful decoding and hence the possibility of cooperation when the direct link is also available. After...
In wireless cooperative networks, the asynchronism between the relays can be a source of diversity which is similar in its essence to the multipath diversity of frequency selective channels. In this context, an asynchronous two-relay cooperative wireless network using the Decode-and-Forward protocol is studied. Two strategies for relay coding are studied: independent coding and repetition coding....
In order to reduce power cost in regenerative relaying system, the concept of power price is proposed, which determined by the different fashions of power supply at the nodes. An algorithm is proposed to minimize the outage probability based on power price, which subjects to the constraint of power cost. Lagrange multiplier maximization method is used to solve this problem. Numerical results show...
In this paper we analyze the performance of a downlink single user multi-cellular multiple inputs single output (MISO) system using the Alamouti code. We derive, for the first time, an analytical expression of the cumulative distribution function of the output signal to interference plus noise ratio (SINR) or equivalently the outage probability in flat Rayleigh fading. The system is considered interference...
The performance of a cooperative network with Cooperative Maximal Ratio Combining (C-MRC) is analyzed. To this end, we propose a heuristic approximation to the total received SNR (signal-to-noise ratio) at the destination. The approximation is not only an accurate representation of the received SNR, but also amenable to performance analysis. We then derive the probability density function (PDF) of...
This paper derives approximations allowing the estimation of outage probability for standard irregular LDPC codes and full-diversity Root-LDPC codes used over nonergodic block-fading channels. Two separate approaches are discussed: a numerical approximation, obtained by curve fitting, for both code ensembles, and an analytical approximation for Root-LDPC codes, obtained under the assumption that the...
The performance of the ALOHA and CSMA protocols is evaluated within a bounded ad hoc network. Our network model comprises packets being distributed in finite space and time according to a 3-D PPP. Upon the formation of each packet, it is transmitted to its intended destination located a fixed distance away, using a fully-distributed MAC protocol. If the SINR of the received packet falls below a certain...
When it comes to space communication networks, there are many different kinds of space vehicles that need to communicate with each other, in space as well as with ground terminals and air borne platform. Example: Geosynchronous Earth orbit (GEO), Low Earth Orbit (LEO) satellites and UAVs. There is an ever growing demand for higher data rates and minimal redundancy, with satellites and various space...
In this paper we present outage regions for two cooperation strategies, namely multi-routing and adaptive multi-routing, if two different coding schemes are used. The first coding scheme is repetition coding and the second one is parallel channel coding. We show that for one cooperation strategy, the outage region for parallel channel coding is a strict subset of the outage probability of repetition...
In this work we consider a relayed transmission link where the relay is equipped with multiple (N) diversity antennas at their inputs and employs selection combining (SC) technique to improve reception from the source before retransmission to the destination via single transmit antenna. The statistical properties of such a link are studied for N Rayleigh-fading channels. The outage probabilities and...
This paper presents the system level performance evaluation for energy-detection based cooperative spectrum sensing in cognitive radio networks. Three performance criteria are quantitively analyzed for cooperative spectrum sensing. First, the average error probability is determined given fixed amplifier gains for a fixed number of secondary users by considering all possible channel realizations. Second,...
The paper introduces an asymptotic series expansion for the mutual information of Multiple-Input Multiple-Output (MIMO) channels. For low signal to noise ratio (SNR) the first term of expansion approaches mutual information from below. Using the low SNR approximation a new water filling power allocation at the transmitter is derived when the receiver and the transmitter have perfect channel state...
In this paper, a single antenna downlink channel with K users is analyzed in the presence of Rayleigh flat fading. A limited channel state information (CSI) feedback scheme is considered, where only 1-bit feedback per user is available at the base station for each fading block. We study the outage performance of such channels. The two cases of short-term and long-term average power constraints are...
With the increasing demand of reliable communications on move, cooperative communications has proved to be an efficient solution to reduce the effects of unreliable nature of wireless channel. In this paper, we study the Space-Time (ST) cooperative communications aided by a fixed relay, forwarding network coded bits to the destination. We present the performance analysis in terms of outage probability...
This paper studies the relay-assisted inter-vehicular communications (IVCs) with double Rayleigh fading vehicle-to-vehicle links. The OPA (optimal power allocation) solution is derived through maximizing source-to-destination channel capacity assuming amplify-and-forward relaying. The outage performance is discussed and the lower bound on outage probability at medium to high SNR (signal-to-noise ratio)...
In this work, we study the problem of optimal power allocation for decode-and-forward cooperative communications. From the perspective of service quality, rather than minimize the outage probability as much as possible, our goal is to use the minimum power to maintain the outage performance below a specific threshold and thereby conserve the power/energy resource. We investigate two scenarios, a system...
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.