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The problem of network coding over a multiple-access channel (MAC) is considered in this paper. Lattice strategies of encoding indexes of messages are proposed, ensuring that if the sum of any two lattice points is another point over a finite field, then the sum of the two indexes mapped to these two points is equal to the index mapped to another point. In this way, the interference caused by other...
This paper proposes the distributed space-time block code (D-STBC) over frequency selective fading channel that achieves both spatial diversity gain and low decoding complexity with decoupling property in amplify-and-forward (AF) relay networks. These two goals are simultaneously achieved by our proposed code design, where the source permutates and conjugates the transmitted data before sending to...
In this paper we consider an interference-free multi-beamforming protocol for multi-source multi-destination relay networks. The new protocol adopts the amplify and forward policy as its cooperative transmission strategy and adjusts the weights of relays to realize an improved multi-pair source-destination data transfer. We in particular investigate the issue how to choose the weights of relays to...
In this paper, we study the problem of joint carrier frequency offset (CFO) and channel estimation for two-way relay network (TWRN) that comprises two source terminals and one relay node. We build up the signal model, from which we identify the CFO and channels at the two source terminals. As the very first attempt to discuss the joint CFO and the channel estimation for TWRN, we consider relay node...
In this paper, we consider the relay selection problem for the cooperative transmission in wireless networks with multiple half-duplex relay nodes. In the existing scheme, by using multiple relay nodes, spatial diversity is exploited to improve the transmission reliability. However, only one relay node is active in each relay-help transmission. We propose a novel relay selection scheme to improve...
Relays can improve wireless links by providing an extra path to the direct path which together form a virtual multiple antenna system. Network Coded-Distributive Antenna System (NC-DAS) and Plain-Distributive Antenna System (PDAS) are examples of realizations of such scenario. Although the asymptotic diversity gain for both the schemes is comparable, the network coded scheme can further take advantage...
In a heterogeneous wireless network, where many different wireless networks interwork together, call admission control is an important issue to distribute user traffic among different access networks in order to provide quality of service (QoS). In this paper, we present and analyze the performance of a call admission control (CAC) policy for voice and data calls, which is based on one-hop cooperation...
In order to avoid the resource inefficiency of all-participated cooperation in wireless amplify-and-forward relay networks, a novel relay selection scheme based on the channel gain of the source-relay and relay-destination links is proposed. A condition is introduced to maximize the upper bound of the overall received signal-to-noise ratio (SNR). The relay nodes which have bad channel conditions are...
This paper analyzes a cooperative diversity scheme in which multiple (i.e., more than two) source nodes cooperate to deliver their packets to a common destination. To obtain spatial diversity, the source nodes form a partnership that enables each source node to transmit its own packets while relaying those of its partners. Instead of time-multiplexing the codewords for local packets and relay packets...
In this paper, we exploit cooperative spectrum sensing technique for applications in a relay based cognitive radio network. Relays are assigned in cognitive radio networks to transmit the primary user's signal to a cognitive coordinator. This research is focused on the detection of primary user in single or multiple cognitive relay scenarios. The performance of energy detector is analyzed for independent...
In this paper, we address the incentive-based relay-selection problem over multi-source and multi-relay wireless networks. A two-side market game approach is employed to jointly consider the benefits of all sources and relays. The equilibrium concept in such games is called core. The outcomes in the core of the game cannot be improved upon by any subset of players. These outcomes correspond exactly...
In this paper, we address the preamble-based channel estimation problem for orthogonal frequency-division multiplexing (OFDM) systems using multiple amplify-and-forward (AF) relays. We first establish a linear minimum mean-square-error (LMMSE) channel estimator which directly estimates the overall channels from the source to the destination. Then, based on the assumption that the channel correlations...
The growth in broadband access and increases in terminal capability have enabled us to provide large-scale multimedia services. The traditional unicast architecture cannot support such a service because the transportation from a content server to many end hosts causes the overload to a content server. Overlay multicast techniques have been proposed to solve this problem. This high-layer technology...
In this paper we study opportunistic communication in two relay channels, the shared relay channel (SRC) and the X-relay channel (XRC). The shared relay channel consists of multiple non-interfering source-destination pairs sharing one relay. The X relay channel is a multi-source multi-destination network where each source has a message for each destination and the network is assisted by one relay...
With demands increasing in lunar and Mars explorations, the need for a new space communication standard protocol is becoming more and more critical. The DTN Research Group (DTNRG) is developing a series of communication protocols with new architecture, generally called DTN protocols, to tolerate highly stressed communication environments with long propagation delays and frequent link disruptions....
In this paper, we propose a semi-blind channel estimation algorithm for amplify-and-forward (AF) relay networks. The algorithm fits well for the recently developed space-time coding (STC) technique in AF relay network that serves for small size terminal and achieve the transmission diversity. Compared to the optimal training based estimators, e.g., maximum likelihood (ML) or linear minimum mean square...
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...
TCP experiences severe performance degradation in cislunar communications because of some assumptions built into its design. Delay/disruption tolerant networking (DTN) is a class of network techniques that is developed to work over Internet protocols to accommodate long link delay and frequent link disruptions in space communication environment. Most of the work concerning DTN protocols and techniques...
In this paper, we investigate the asymptotic e-outage capacity of a half-duplex large fading relay network, which consists of one source node, one destination node, and N relay nodes. The relay nodes are assumed to be randomly deployed in a given area and under fatal independent random attacks with probability p. With a total power constraint on all the nodes, we examine the e-outage rate of the amplify-and-forward...
In this paper, we address the robust linear transceiver design for dual-hop amplify-and-forward (AF) MIMO relay systems, where both transmitters and receivers have imperfect channel state information (CSI). With the statistics of channel estimation errors in the two hops being Gaussian, we formulate the robust linear-minimum-mean-square-error (LMMSE) transceiver design problem using the Bayesian framework,...
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