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60
Energy-efficient cooperative communication based on power control and selective single-relay in wireless sensor networks
- IEEE Trans. Wireless Commun
, 2008
"... Abstract—Cooperative communication with single relay selection is a simple but effective communication scheme for energyconstrained networks. In this paper, we propose a novel selective single-relay cooperative scheme, combining selective-relay cooperative communication with physical-layer power con ..."
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Cited by 35 (0 self)
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Abstract—Cooperative communication with single relay selection is a simple but effective communication scheme for energyconstrained networks. In this paper, we propose a novel selective single-relay cooperative scheme, combining selective-relay cooperative communication with physical-layer power control. Based on the MAC-layer RTS-CTS signaling, a set of potential relays compute individually the required transmission power to participate in the cooperative communication, and compete within a window of fixed length. The “best ” relay is selected in a distributed fashion with minimum signaling overhead. We derive power-control solutions corresponding to two policies on relay selection: One is to minimize the energy consumption per data packet, and the other is to maximize the network lifetime. Our numerical and simulation results confirm that the proposed scheme achieves significant energy savings and prolongs the network lifetime considerably. Index Terms—Selective relay cooperation, energy efficiency, wireless sensor networks, power control. I.
Splitting Algorithms for Fast Relay Selection: Generalizations, Analysis, and a Unified View
, 2010
"... Relay selection for cooperative communications promises significant performance improvements, and is, therefore, attracting, considerable attention. While several criteria have been proposed for selecting one or more relays, distributed mechanisms that perform the selection have received relatively ..."
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Cited by 20 (15 self)
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Relay selection for cooperative communications promises significant performance improvements, and is, therefore, attracting, considerable attention. While several criteria have been proposed for selecting one or more relays, distributed mechanisms that perform the selection have received relatively less attention. In this paper, we develop a novel, yet simple, asymptotic analysis of a splitting-based multiple access selection algorithm to find the single best relay. The analysis leads to simpler and alternate expressions for the average number of slots required to find the best user. By introducing a new ’contention load ’ parameter, the analysis shows that the parameter settings used in the existing literature can be improved upon. New and simple bounds are also derived. Furthermore, we propose a new algorithm that addresses the general problem of selecting the best Q 1 relays, and analyze and optimize it. Even for a large number of relays, the scalable algorithm selects the best two relays within 4.406 slots and the best three within 6.491 slots, on average. We also propose a new and simple scheme for the practically relevant case of discrete metrics. Altogether, our results develop a unifying perspective about the general problem of distributed selection in cooperative systems and several other multi-node systems.
Relay Subset Selection in Wireless Networks Using Partial Decode-and-Forward Transmission
"... Abstract — This paper considers the problem of selecting a set of relay nodes to assist a transmitting node in a two-hop wireless network. Throughput-maximizing relay subset selection is a difficult problem that depends on variables such as node locations and power constraints. It is proposed that a ..."
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Cited by 16 (4 self)
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Abstract — This paper considers the problem of selecting a set of relay nodes to assist a transmitting node in a two-hop wireless network. Throughput-maximizing relay subset selection is a difficult problem that depends on variables such as node locations and power constraints. It is proposed that all relays employ partial decode-and-forward operations to improve the tractability of the relay selection problem. This allows relay selection to be transformed into a simpler relay placement problem which motivates two proximity-based relay selection algorithms. These algorithms are compared with a greedy algorithm based on relay channel gains to the destination and an algorithm that randomly selects relays. The diversity gain achieved by employing multiple relay nodes is derived. The proposed proximity-based algorithms offer good performance in terms of the expected achieved rate. I.
Relay selection with network coding in twoway relay channels
- IEEE Trans. Veh. Technol
, 2010
"... Abstract—In this paper, we consider the design of joint network coding (NC) and relay selection (RS) in two-way relay channels. In the proposed schemes, two users first sequentially broadcast their respective information to all the relays. We propose two RS schemes: 1) a single RS with NC and 2) a d ..."
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Cited by 14 (0 self)
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Abstract—In this paper, we consider the design of joint network coding (NC) and relay selection (RS) in two-way relay channels. In the proposed schemes, two users first sequentially broadcast their respective information to all the relays. We propose two RS schemes: 1) a single RS with NC and 2) a dual RS with NC. For both schemes, the selected relays perform NC on the received signals sent from the two users and forward them to both users. The proposed schemes are analyzed, and the exact bit-error-rate (BER) expressions are derived and verified through Monte Carlo simulations. It is shown that the dual RS with NC outperforms other considered RS schemes in two-way relay channels. The results also reveal that the proposed RS–NC schemes provide a selection gain compared with an NC scheme with no RS and an NC gain relative to a conventional RS scheme with no NC. Index Terms—Bidirectional relay, cooperative communications, decode and forward (DAF), network coding (NC), relay networks, selective relaying, two-way relay channels. I.
K.K.: ‘Distributed beamforming and power allocation for cooperative networks
- IEEE Trans. Wirel. Commun
"... Cooperative diversity systems rely on using relay nodes to relay copies of transmitted information to the destination such that each copy experiences different channel fading, hence increasing the diversity of the system. However, without proper processing of the message at the relays, the performan ..."
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Cited by 13 (3 self)
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Cooperative diversity systems rely on using relay nodes to relay copies of transmitted information to the destination such that each copy experiences different channel fading, hence increasing the diversity of the system. However, without proper processing of the message at the relays, the performance of the cooperative system may not necessarily perform better than direct transmission systems. In this paper, we proposed a distributed beamforming and power allocation algorithm which substantially improves the diversity of the system with only very limited feedback from the destination node. We also derive outage probability as well as study the outage behavior of this scheme. I.
The relay selection and transmission trade-off in cooperative communication systems
- IEEE Trans. Wireless Commun
, 2010
"... A common and practical paradigm in cooperative communication systems is the use of a dynamically selected best relay to decode and forward information from a source to a destination. Such systems use two phases a relay selection phase, in which the system uses transmission time and energy to select ..."
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Cited by 13 (7 self)
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A common and practical paradigm in cooperative communication systems is the use of a dynamically selected best relay to decode and forward information from a source to a destination. Such systems use two phases a relay selection phase, in which the system uses transmission time and energy to select the best relay, and a data transmission phase, in which it uses the spatial diversity benefits of selection to transmit data. In this paper, we derive closed-form expressions for the overall throughput and energy consumption, and study the time and energy trade-off between the selection and data transmission phases. To this end, we analyze a baseline non-adaptive system and several adaptive systems that adapt the selection phase, relay transmission power, or transmission time. Our results show that while selection yields significant benefits, the selection phases time and energy overhead can be significant. In fact, at the optimal point, the selection can be far from perfect, and depends on the number of relays and the mode of adaptation. The results also provide guidelines about the optimal system operating point for different modes of adaptation. The analysis also sheds new insights on the fast splitting-based algorithm considered in this paper for relay selection.
Cooperative relay networks using fountain codes
- in Proceedings of the IEEE Global Telecommunications Conference
, 2006
"... We investigate a cooperative communications scheme with N parallel relays, where both the transmissions from the source to the relays and from the relays to the destination use fountain codes. Receiver for codes can accumulate mutual information, while traditional energy collection methods, such as ..."
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Cited by 11 (6 self)
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We investigate a cooperative communications scheme with N parallel relays, where both the transmissions from the source to the relays and from the relays to the destination use fountain codes. Receiver for codes can accumulate mutual information, while traditional energy collection methods, such as repetition or cooperative space-time codes, only accumulate energy. As a consequence, using fountain codes can reduce the total energy required for transmitting data from the source to the destination. We first analyze the scenario where the source stops transmitting and the relay nodes start transmitting after L relay nodes have successfully decoded the source data. We optimize L, and also give closed-form equations for the energy savings that can be achieved by the use of mutual-information-collection at the receiver instead of the traditional energy-collection methods. We then analyze an alternate scenario where each relay node starts its transmission to the destination as soon as it has decoded the source data, and helps the other relay nodes that are still in reception mode. Doing so further reduces the total transmission time and energy consumption.
Robust wireless relay networks: slow power allocation with guaranteed QoS
- Istanbul Technical University
, 2007
"... Abstract—In wireless networks, power allocation is an effective technique for prolonging network lifetime, achieving better quality-of-service (QoS), and reducing network interference. However, these benefits depend on knowledge of the channel state information (CSI), which is hardly perfect. Theref ..."
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Cited by 10 (1 self)
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Abstract—In wireless networks, power allocation is an effective technique for prolonging network lifetime, achieving better quality-of-service (QoS), and reducing network interference. However, these benefits depend on knowledge of the channel state information (CSI), which is hardly perfect. Therefore, robust algorithms that take into account such CSI uncertainties play an important role in the design of practical systems. In this paper, we develop relay power allocation algorithms for noncoherent and coherent amplify-and-forward (AF) relay networks. The goal is to minimize the total relay transmission power under individual relay power constraints, while satisfying a QoS requirement. To make our algorithms practical and attractive, our power update rate is designed to follow large-scale fading, i.e., in the order of seconds. We show that, in the presence of perfect global CSI, our power optimization problems for noncoherent and coherent AF relay networks can be formulated as a linear program and a second-order cone program (SOCP), respectively. We then introduce robust optimization methodology that accounts for uncertainties in the global CSI. In the presence of ellipsoidal uncertainty sets, the robust counterparts of our optimization problems for noncoherent and coherent AF relay networks are shown to be an SOCP and a semi-definite program, respectively. Our results reveal that ignoring uncertainties associated with global CSI often leads to poor performance. We verify that our proposed algorithms can provide significant power savings over a naive scheme that employs maximum transmission power at each relay node. This work highlights the importance of robust algorithms with practical power update rates in realistic wireless networks. Index Terms—Amplify-and-forward, linear program, quality-of-service, relay networks, robust optimization, semi-definite program, slow power allocation. I.
Progressive accumulative routing: Fundamental concepts and protocol
- IEEE Trans. Wireless Comm
, 2008
"... This paper considers a multi-hop network in which relay nodes cooperate to minimize the total energy consumed in transmitting a (unicast) packet from a source to a destination. We propose the Progressive Accumulative Routing (PAR) algorithm, which progressively performs relay discovery, relay orderi ..."
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Cited by 7 (4 self)
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This paper considers a multi-hop network in which relay nodes cooperate to minimize the total energy consumed in transmitting a (unicast) packet from a source to a destination. We propose the Progressive Accumulative Routing (PAR) algorithm, which progressively performs relay discovery, relay ordering and relay power allocation in a distributed manner, such that each relay node only needs local information. We assume Destination Energy Accumulation, in which the destination accumulates the energy of multiple received copies of a packet, each of which is too weak to be reliably decoded by itself, while the lower-complexity relay nodes use a decodeand-forward approach. We also provide a closed-form analysis of the energy-saving achieved by the PAR when a relay node is added to an already existing DEA route. Simulations verify that the algorithm considerably reduces the total energy consumption, and can be implemented efficiently.
Routing in cooperative wireless networks with mutual-information accumulation
- in Proc. IEEE ICC 2008
, 2008
"... Cooperation between the nodes of wireless multihop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual-information accumulation, e.g., by using rateless codes. In this paper, we investi ..."
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Cited by 7 (2 self)
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Cooperation between the nodes of wireless multihop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual-information accumulation, e.g., by using rateless codes. In this paper, we investigate routing problems in such networks. Given a network, a source and a destination, our objective is to minimize end-to-end transmission delay under a sum energy constraint. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any node decoding order we show that solving for the optimum resource allocation can be formulated as a linear problem. We then show that the decoding order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear program leads to a locally optimum solution in a very efficient manner. In comparison to the cooperative routing, it is observed that conventional shortest-path multihop routings incur additional delays and energy expenditures on the order of 70%. Since this initial solution is centralized, requiring full channel stat information, we exploit the insights to design two distributed routing algorithms that require only local channel state information. We provide simulations showing that in the same networks the distributed algorithms find routes that are only about 2-5 % less efficient than the centralized solution.
