Results 1  10
of
21
Recent and Emerging Topics in Wireless Industrial Communications: A Selection
, 2007
"... In this paper we discuss a selection of promising and interesting research areas in the design of protocols and systemsforwirelessindustrialcommunications.Wehaveselected topicsthathaveeitheremergedashottopicsintheindustrial communicationscommunityinthelastfewyears(likewireless sensornetworks),orwhi ..."
Abstract

Cited by 96 (1 self)
 Add to MetaCart
(Show Context)
In this paper we discuss a selection of promising and interesting research areas in the design of protocols and systemsforwirelessindustrialcommunications.Wehaveselected topicsthathaveeitheremergedashottopicsintheindustrial communicationscommunityinthelastfewyears(likewireless sensornetworks),orwhichcouldbeworthwhileresearchtopicsin thenextfewyears(forexamplecooperativediversitytechniques for error control, cognitive radio/opportunistic spectrum access for mitigation of external interferences).
Clusterbased Cooperative Communication with Network Coding in Wireless Networks
 IEEE MILCOM
"... Abstract—Cooperative communication is a promising way to reduce probability of packet loss. The massive deployment of nodes in wireless sensor network renders such networks especially attractive for exploiting the advantage of cooperative diversity. Similarly, when used appropriately, network coding ..."
Abstract

Cited by 7 (2 self)
 Add to MetaCart
(Show Context)
Abstract—Cooperative communication is a promising way to reduce probability of packet loss. The massive deployment of nodes in wireless sensor network renders such networks especially attractive for exploiting the advantage of cooperative diversity. Similarly, when used appropriately, network coding could also improve the probability of correct reception. In this paper, we introduce the clusterbased Cooperative Coding (CC) protocol, which is based on the integration of cooperative communication and network coding. In particular, in the CC protocol, network nodes are grouped into multiple clusters and nodes within the same cluster cooperate in transmitting and receiving packets. Such an integration reduces the amount of redundant information being forwarded to ensure high probability of correct endtoend reception, when linklevel retransmission of erroneous packets is not allowed (i.e., no linklevel feedback). In particular, our analysis shows how to optimize the performance of the network by properly sizing the clusters. Compared to schemes without cooperation (whether with or without network coding), our simulation results demonstrate the significant performance improvement of the proposed scheme.
On optimal cooperator selection policies for multihop ad hoc networks
 IEEE Trans. Wireless Commun
, 2011
"... Abstract—In this paper we consider wireless cooperative multihop networks, where nodes that have decoded the message at the previous hop cooperate in the transmission toward the next hop, realizing a distributed spacetime coding scheme. Our objective is finding optimal cooperator selection policie ..."
Abstract

Cited by 5 (1 self)
 Add to MetaCart
(Show Context)
Abstract—In this paper we consider wireless cooperative multihop networks, where nodes that have decoded the message at the previous hop cooperate in the transmission toward the next hop, realizing a distributed spacetime coding scheme. Our objective is finding optimal cooperator selection policies for arbitrary topologies with links affected by path loss and multipath fading. To this end, we model the network behavior through a suitable Markov chain and we formulate the cooperator selection process as a stochastic shortest path problem (SSP). Further, we reduce the complexity of the SSP through a novel pruning technique that, starting from the original problem, obtains a reduced Markov chain which is finally embedded into a solver based on focused real time dynamic programming (FRTDP). Our algorithm can find cooperator selection policies for large state spaces and has a bounded (and small) additional cost with respect to that of optimal solutions. Finally, for selected network topologies, we show results which are relevant to the design of practical network protocols and discuss the impact of the set of nodes that are allowed to cooperate at each hop, the optimization criterion and the maximum number of cooperating nodes. Index Terms—Ad hoc wireless networks, automatic repeat request, cooperative communication, MIMO systems, multihop communication, optimal policies. I.
Energyspectral efficiency tradeoff in virtual MIMO cellular systems
 IEEE J. Sel. Areas Commun
, 2013
"... technology promises significant performance enhancements to cellular systems in terms of spectral efficiency (SE) and energy efficiency (EE). How these two conflicting metrics scale up in large cellular VMIMO networks is unclear. This paper studies the EESE tradeoff of the uplink of a multiuser ..."
Abstract

Cited by 5 (4 self)
 Add to MetaCart
(Show Context)
technology promises significant performance enhancements to cellular systems in terms of spectral efficiency (SE) and energy efficiency (EE). How these two conflicting metrics scale up in large cellular VMIMO networks is unclear. This paper studies the EESE tradeoff of the uplink of a multiuser cellular VMIMO system with decodeandforward type protocols. We first express the tradeoff in an implicit function and further derive closedform formulas of the tradeoff in low and high SE regimes. Unlike conventional MIMO systems, the EESE tradeoff of the VMIMO system is shown to be susceptible to many factors including protocol design (e.g., resource allocation) and scenario characteristics (e.g., user density). Focusing on the medium and high SE regimes, we propose a heuristic resource allocation algorithm to optimize the EESE tradeoff. The fundamental performance limits of the optimized VMIMO system are subsequently investigated and compared with conventional MIMO systems in different scenarios. Numerical results reveal a surprisingly chaotic behavior of VMIMO systems when the user density scales up. Our analysis indicates that low frequency reuse factor, adaptive resource allocation, and user density control are critical to harness the full benefits of cellular VMIMO systems. Index Terms—Energy efficiency, spectral efficiency, virtual MIMO, adaptive resource allocation. I.
Randomised collaborative transmission of smart objects
 in 2nd International Workshop on Design and Integration
, 2008
"... We propose a randomised approach to time and frequency synchronisation of superimposed received signals from collaboratively transmitting smart objects. The technique is feasible without communication between nodes and entirely relies on the receiver feedback. It is practical for an arbitrary number ..."
Abstract

Cited by 4 (3 self)
 Add to MetaCart
(Show Context)
We propose a randomised approach to time and frequency synchronisation of superimposed received signals from collaboratively transmitting smart objects. The technique is feasible without communication between nodes and entirely relies on the receiver feedback. It is practical for an arbitrary number of received signals and transmitter nodes. The superimposed received signal has its maximum constructive interference focused on an arbitrary location of a remote receiver. In both, analytic considerations and in a simulation environment we demonstrate that synchronisation of several hundred received signals is possible within milliseconds.
FeedbackBased ClosedLoop Carrier Synchronization: A Sharp Asymptotic Bound, an Asymptotically Optimal Approach, Simulations, and Experiments
"... Abstract—We derive an asymptotically sharp bound on the synchronization speed of a randomized black box optimization technique for closedloop feedbackbased distributed adaptive beamforming in wireless sensor networks. We also show that the feedback function that guides this synchronization process ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
Abstract—We derive an asymptotically sharp bound on the synchronization speed of a randomized black box optimization technique for closedloop feedbackbased distributed adaptive beamforming in wireless sensor networks. We also show that the feedback function that guides this synchronization process is weak multimodal. Given this knowledge that no local optimum exists, we consider an approach to locally compute the phase offset of each individual carrier signal. With this design objective, an asymptotically optimal algorithm is derived. Additionally, we discuss the concept to reduce the optimization time and energy consumption by hierarchically clustering the network into subsets of nodes that achieve beamforming successively over all clusters. For the approaches discussed, we demonstrate their practical feasibility in simulations and experiments. Index Terms—Analysis of algorithms, wireless communication, wireless sensor networks. Ç 1
1 RelayAssisted Transmission with Fairness Constraint for Cellular Networks
"... Abstract—We consider the problem of relayassisted transmission for cellular networks. In the considered system, a source node together with n relay nodes are selected in a proportionally fair (PF) manner to transmit to the base station (BS), which uses the maximal ratio combining (MRC) to combine t ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
Abstract—We consider the problem of relayassisted transmission for cellular networks. In the considered system, a source node together with n relay nodes are selected in a proportionally fair (PF) manner to transmit to the base station (BS), which uses the maximal ratio combining (MRC) to combine the signals received from the source node in the first half slot and the n relay nodes in the second half slot for successful reception. The proposed algorithm incorporates the PF criterion and cooperative diversity, and is called proportionally fair cooperation (PFC). Compared with the proportional fair scheduling (PFS) algorithm, PFC provides improved efficiency and fairness. The ordinary differential equation (ODE) analysis used to study PFS cannot be used for PFC, otherwise one has to solve a large number of nonlinear and interrelated ODE equations which is timeprohibited. In this paper, we present a mathematical framework for the performance of PFC. The cornerstone of our framework is a realistic yet simple model that captures node cooperation, fading, and fair resource allocationinduced dependencies. We obtain analytical expressions for the throughput gain of PFC over traditional PFS without node cooperation. Compared with the highly timeconsuming ordinary differential equation (ODE) analysis, our formulae are intuitive yet easy to evaluate numerically. To our knowledge, it is the first time that a closedform expression is obtained for the throughput of relayassisted transmission in a cellular network with the PF constraint. Index Terms—relayassisted transmission, proportional fairness, cellular networks. I.
Distributed orthogonal space–time coding: Design and outage analysis for randomized cooperation
 IEEE Trans. Wireless Commun
, 2007
"... Abstract — In this paper we consider a cooperative wireless network where each terminal communicates to a destination node with the aid of multiple relaying nodes. The focus is on cooperative transmission protocols that are based on the simultaneous transmission by a number of cooperating nodes. Out ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
(Show Context)
Abstract — In this paper we consider a cooperative wireless network where each terminal communicates to a destination node with the aid of multiple relaying nodes. The focus is on cooperative transmission protocols that are based on the simultaneous transmission by a number of cooperating nodes. Outage performances are analyzed by assuming a Distributed Randomized Orthogonal SpaceTime Coding scheme (DROSTC) to be employed by the relaying terminals during the transmission session. The DROSTC scheme requires that each cooperating node chooses randomly and independently to serve as one of the spacetime virtual antennas. By avoiding any predefined terminaltocodeword mapping, the random selection of the spacetime codewords substantially reduces the needed control overhead with respect to other distributed spacetime coding strategies simplifying the node coordination task. According to this scheme, in this paper it is tackled the problem of designing both the minimum number of cooperating nodes M and the spatial dimension L of the spacetime code matrix so as to meet a specific outage probability requirement at the destination. Outage performances are also analyzed by developing simple but effective design rules tailored for two cooperative trasmission protocols in realistic propagation environments. Index Terms — Distributed spacetime coding, cooperative diversity, spacetime coding design, adhoc and sensors networks, wireless networks. I.
CrossLayer Optimization Frameworks for Multihop Wireless Networks Using Cooperative Diversity
"... Abstract—We propose crosslayer optimization frameworks for multihop wireless networks using cooperative diversity. These frameworks provide solutions to fundamental relaying problems of determining who should be relays for whom and how to perform resource allocation for these relaying schemes joint ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
(Show Context)
Abstract—We propose crosslayer optimization frameworks for multihop wireless networks using cooperative diversity. These frameworks provide solutions to fundamental relaying problems of determining who should be relays for whom and how to perform resource allocation for these relaying schemes jointly with routing and congestion control such that the system performance is optimized. We present a fully distributed algorithm where the joint routing, relay selection, and power allocation problem to minimize network power consumption is solved by using convex optimization. Via dual decomposition, the master optimization problem is decomposed into a routing subproblem in the network layer and a joint relay selection and power allocation subproblem in the physical layer, which can be solved efficiently in a distributed manner. We then extend the framework to incorporate congestion control and develop a framework for optimizing the sum rate utility and power tradeoff for wireless networks using cooperative diversity. The numerical results show the convergence of the proposed algorithms and significant improvement in terms of power consumption and source rates due to cooperative diversity. Index Terms—Cooperative diversity, multihop wireless network, mesh network, convex optimization, crosslayer design, network utility maximization, routing, power control. I.
EFFECT OF MUTUAL COUPLING ON THE ENERGY REQUIREMENT OF MIMOBASED WIRELESS SENSOR NETWORKS
"... A theoretical model was developed to estimate effect of the mutual coupling on the energy requirement of a multipleinput multipleoutput (MIMO) based wireless sensor network (WSN). Clustered channel modeling with Rician fading distribution is assumed to include the effect of the lineofsight (LOS) ..."
Abstract
 Add to MetaCart
A theoretical model was developed to estimate effect of the mutual coupling on the energy requirement of a multipleinput multipleoutput (MIMO) based wireless sensor network (WSN). Clustered channel modeling with Rician fading distribution is assumed to include the effect of the lineofsight (LOS) ray paths. The effect of propagation environments is included in the analysis by assuming a twoslope path loss model. The effect of knowing the channel state information (CS) in the MIMO system (MIMo,i) is also included in the analysis. It is shown that the presence of mutual coupling between elements of MIMO array decreases the energy required by the MIMO based WSN. Simulation results also show that it is possible to use a compact circular antenna array with a quarter wavelength diameter to build a MIMO,,i based WSN that requires almost constant energy for applications that cover a range from few meters up to around 100m. Index Terms Energy efficiency, multipleinput multipleoutput (MIMO), wireless sensors networks.