Two-hop Wireless Network Research Articles

Buffer-aided relay selection for secure communication in two-hop wireless networks with limited packet lifetime

Buffer-aided relay selection serves as one of the key approaches for achieving physical layer security (PLS) of wireless networks. Existing studies on buffer-aided relay selection mainly concentrate on the scenarios where transmitted packets have unlimited lifetime, while the more practical and important scenarios with limited packet lifetime remain largely unexplored. This paper therefore aims to study the buffer-aided relay selection for achieving PLS in two-hop wireless networks with limited packet lifetime. We first propose a novel buffer-aided relay selection scheme by carefully considering the remaining lifetimes of packets, conditions of available links and channel state information (CSI) of eavesdroppers. To model the security and reliability performances achieved by the proposed scheme, we then apply tools from the Markov chain theory to derive expressions of the secrecy outage probability (SOP) and the packet discarding probability (PDP) of the network, respectively. Finally, extensive simulation and numerical results are provided to illustrate the performances of our proposed scheme and our theoretical framework. The results show that although our scheme achieves a slightly higher SOP than the typical buffer-aided max-link relay selection scheme, it can greatly reduce the PDP of the network.

Buffer-aided relay selection for secure two-hop wireless networks with decode-and-forward relays and a diversity-combining eavesdropper

This paper investigates the buffer-aided relay selection issue for achieving physical layer security (PLS) in two-hop wireless networks with Decode-and-Forward (DF) relays. Available works mainly focus on scenarios with independent-decoding eavesdroppers. However, the more hazardous scenarios with diversity-combining eavesdroppers that combine the signals in two hops to decode the packets are largely ignored. This paper considers a two-hop wireless network with multiple DF relays and one diversity-combining eavesdropper under two cases with perfect and partial eavesdropper channel state information (CSI) respectively. We first propose two secure buffer-aided relay selection schemes to suppress the eavesdropper for both eavesdropper CSI cases respectively. We then derive analytical expressions for the end-to-end (E2E) secure transmission probability (STP) and E2E delay of the network. Finally, we provide extensive simulation and numerical results to validate the correctness of the expressions and also to investigate the E2E STP and E2E delay performances. The results showed that the proposed schemes can achieve better E2E STP performance than the well-known Max-ratio buffer-aided relay selection scheme but at the cost of an increased E2E delay.

On Security-Delay Trade-Off in Two-Hop Wireless Networks With Buffer-Aided Relay Selection

This paper investigates the security-delay trade-off of the buffer-aided relay selection scheme in a two-hop wireless system, which consists of a source-destination pair, one eavesdropper, and multiple relays each having a finite buffer. To evaluate the security and delay performances of the system, we derive analytical expressions for the end-to-end (E2E) secure transmission probability (STP) and the expected E2E delay under both perfect and partial eavesdropper channel state information (CSI) cases. These analytical expressions help us to explore the inherent trade-off between the security and delay performances of the concerned system. In particular, the results in this paper indicate that: 1) the maximum E2E STP increases as the constraint on the expected E2E delay becomes less strict, and such trend is more sensitive to the variation of the number of relays than that of the relay buffer size; 2) on the other hand, the minimum expected E2E delay tends to decrease when a less strict constraint on E2E STP is imposed, and this trend is more sensitive to the variation of the relay buffer size than that of the number of relays.

Energy-Aware Routing for SWIPT in Multi-Hop Energy-Constrained Wireless Network

Simultaneous wireless information and power transfer (SWIPT) transmits information and powers wireless nodes with the same radio frequency signal. It can prolong the life time of the energy-constrained wireless nodes. Current works of SWIPT focus on one-hop and two-hop wireless network. In order to verify the performance of SWIPT in multi-hop energy-constrained wireless network (MECWN) where the energy harvested by the receiver node can be as an energy compensation for data forwarding, this paper concurrently considers SWIPT and routing selection in MECWN. To reduce the energy consumption, we first formulate the information and energy allocation problem of link in a forwarding path, which is dependent on the next-hop node, and solve it by an iterative allocation algorithm. A novel routing metric evaluates the energy consumption of link transmitted with or without SWIPT. The energy-aware SWIPT routing algorithm allocates the information and energy of link with allocation algorithm during path finding process. To the best of our knowledge, this is the first solution that takes account of SWIPT and routing in MECWN. Our performance studies demonstrate that our proposed algorithms can effectively exploit those node resources whose energy are not enough and significantly decrease the energy consumption.

Cooperative Secrecy to Resist Authentication Error in Two‐Hop Wireless Networks

The authentication error in two-hop wireless networks is considered without knowledge of eavesdropper channels and location. The wireless informationtheoretic security has attracted considerable attention recently. A prerequisite for available works is the precise distinction between legitimate nodes and eavesdroppers. However it is unrealistic in the wireless environment. Error is always existing in the node authentication process. Best of our knowledge, there are no works focus on solving this problem in the information-theoretic security. This paper presents a eavesdropper model with authentication error and two eavesdropping ways. Then, the number of eavesdroppers can be tolerated is analyzed while the desired secrecy is achieved with high probability in the limit of a large number of relay nodes. Final, we draw two conclusions for authentication error: 1) The impersonate nodes are chosen as relay is the dominant factor of the transmitted message leakage, and the impersonation attack does seriously decrease the number of eavesdroppers can be tolerated. 2) The error authentication to legitimate nodes is almost no effect on the number of eavesdroppers can be tolerated.

Queuing Analysis of Two-Hop Relay Technology in LTE/LTE-A Networks With Unsaturated and Asymmetric Traffic

Relay technology is one of the key technologies for long-term evolution advanced (LTE-A) project. The introduction of relay will not only bring a wider coverage and higher capacity to the system but also lower the cost of network building. Multihop wireless relay technology plays an important role in next-generation mobile and wireless communication systems. Nowadays, we are witnessing the formation of a new technological marvel: Internet of Things (IoT). This formation is able to combine in a particular operational entity, all the bits and pieces of the world around us. In this paper, we perform queuing modeling of a two-hop wireless relay network and carry out performance analysis of end-to-end packet delay. In the two-hop wireless relay network, two groups of wireless nodes (WNs) and a single relay node (RN) are considered. A Poisson packet arrival process and IEEE 802.11 distributed coordination function are assumed in the network for the network traffic model and for regulating the nodes’ access to the shared channel, respectively. We model a node as a single-server queuing system, whose service time of a packet is unknown and dependent on the probabilistic parameters of IEEE 802.11 DCF medium access control (MAC). A system of equations is then obtained for numerically computing the probabilistic parameters of IEEE 802.11 DCF MAC through discretization of the continuous-time network operations, based on which we construct semi-Markov processes and derive an analytic result for the expectation of the end-to-end packet delay. As a key performance indicator in evaluation of wireless networks, the packet delay result helps measure the efficiency of IEEE 802.11 MAC in two-hop wireless relay networks.

Incentivizing Signal and Energy Cooperation in Wireless Networks

We consider a two-hop wireless network where the source(s) in the network have the ability to wirelessly power the relay(s) who also have their own data to send to the destination. Considering the fact that each node in the network aims to maximize its own metric, we adopt a game theoretic approach that foresees offering relaying of the sources’ data in exchange for energy provided to the relays, and simultaneously offering energy to the relays in exchange for their relaying services. We first study a Stackelberg competition with the single relay node as the leader, and investigate the impact of having multiple source nodes in the system. We next study the reciprocal Stackelberg game with the single source as the leader, and investigate the inter-relay competition with multiple relays. We find that in the Stackelberg games, the leader can improve its individual utility by influencing the follower’s decision accordingly, even more so when there are multiple followers. We next formulate a noncooperative game between the source and the relay and show the existence of a unique Nash equilibrium by an appropriate pricing mechanism. The equilibrium maximizes the total utility of the network and allows the destination to choose how much data to receive from each node.

Cooperative Transmission against Impersonation Attack and Authentication Error in Two-Hop Wireless Networks

The wireless information-theoretic security from inter-session interference has attracted considerable attention recently. A prerequisite for available works is the precise distinction between legitimate nodes and eavesdroppers. However, the authentication error always exists in the node authentication process in Two-Hop wireless networks. This paper presents an eavesdropper model with authentication error and two eavesdropping ways. Then, the number of eavesdroppers can be tolerated is analyzed while the desired secrecy is achieved with high probability in the limit of a large number of relay nodes. Final, we draw two conclusions for authentication error: 1) the impersonate nodes are chosen as relay is the dominant factor of the transmitted message leakage, and the impersonation attack does seriously decrease the number of eavesdroppers can be tolerated. 2) The error authentication to legitimate nodes is almost no effect on the number of eavesdroppers can be tolerated.

Markovian Process and Novel Secure Algorithm for Big Data in Two-Hop Wireless Networks

This paper checks the correctness of our novel algorithm for secure, reliable and flexible transmission of big data in two-hop wireless networks using cooperative jamming scheme of attacker location unknown through Markovian process. Big data has to transmit in two-hop from source-to-relay and relay-to-destination node by deploying security in physical layer. Based on our novel algorithm, the nodes of the network can be identifiable, the probability value of the data absorbing nodes namely capture node C, non-capture node NC, eavesdropper node E, in each level depends upon the present level to the next level, the probability of transition between two nodes is same at all times in a given time slot to ensure more secure transmission of big data. In this paper, maximum probability for capture nodes is considered to justify the efficient transmission of big data through Markovian process.

Performance Evaluation of Two-Hop Wireless Network under Asymmetric Fading Environment

To enhance the reliability of long wireless link, a relay is placed between transmitter and receiver which break the link into two parts: transmitter to relay called 1st hop and relay to receiver called 2nd hop; such arrangement is called two hop wireless links. In two-hop wireless communication sometimes 1st and 2nd hops are affected by different types of fading called asymmetric fading environment. In this paper we consider four different combinations of Rayleigh and Nakagami-m fading on 1st and 2nd hop to observe the profile of combined pdf (probability density function) and cdf (cumulative distribution function). With the help of cdf we determine the variation of outage probability of mixed fading. Finally we plot the SER (symbol error rate) against the SNR (signal to noise ratio) of the 2nd hop for all possible combinations of the two fading taking the SNR of 1st hop as a parameter. Although recent literature deals with asymmetric fading environment but in this paper instead of details statistical model of such fading we provide the relative scenario of mixed fading on 2-hop wireless link.

MPSK Symbol-based Soft-Information-Forwarding Scheme in Rayleigh Fading Channels

In this paper, we proposed a symbol-based multiple phase shift keying (MPSK) soft-information-forwarding (SIF) scheme for a two-hop parallel relay wireless network in Rayleigh fading channel. First the binary information streams at the source are mapped into MPSK symbols, and the relays construct the relay processing function by passing the intermediate soft decisions. Then the relays broadcast the processed symbols to the destination. After the maximum ratio combination, the received symbols at the destination can be decided by maximum-likelihood (ML) decision. Four MPSK symbol-based forwarding schemes are investigated and the simulation results show that the bit error rate (BER) performance of soft information forwarding scheme has better BER performance than the existing memoryless forwarding scheme based on MPSK modulation, and it is more practical than the SIF scheme based on BPSK modulation

Transmission protocol for secure big data in two-hop wireless networks with cooperative jamming

Wireless communications nowadays are increasingly becoming irreplaceable networking technologies for military, governmental and financial communications where the data is exploding in volume, variety and velocity, called big data. This poses great challenges to ensuring security through cryptography. Recently, cooperative jamming has been proved as a promising physical layer technique to provide the everlasting security for wireless networks. Based on this scheme, this paper proposes a two-hop transmission protocol with parameters l, k,r and τ (2HR-(l,k,r,τ)) to ensure secure and reliable big data transmissions in wireless networks with multiple eavesdroppers. We first determine the relay selection region (RSR) as the square of side-length l centered at the middle point between the source and the destination. Then one of the k best relays located in the RSR is randomly selected as the message relay. During the forwarding in both hops, the remaining relays at least distance r away from the intended receivers and with channel gain to the intended receivers less than τ are selected to generate jamming signals to confuse the eavesdroppers. The results in this paper indicate that our protocol can provide flexible control of security, reliability and the energy balance performance, which characterizes how energy consumption for forwarding message is balanced among all the relays.

Degrees of Freedom of Two-Hop Wireless Networks: Everyone Gets the Entire Cake

We show that fully connected two-hop wireless networks with K sources, K relays, and K destinations have K degrees of freedom both in the case of time-varying channel coefficients and constant channel coefficients (in which case the result holds for almost all values of constant channel coefficients). Our main contribution is a new achievability scheme which we call Aligned Network Diagonalization. This scheme allows the data streams transmitted by the sources to undergo a diagonal linear transformation from the sources to the destinations, thus being received free of interference by their intended destination. In addition, we extend our scheme to multihop networks with fully connected hops, and multihop networks with MIMO nodes, for which the degrees of freedom are also fully characterized.

Exploring Relay Cooperation for Secure and Reliable Transmission in Two-HopWireless Networks

Exploring Relay Cooperation for Secure and Reliable Transmission in Two-HopWireless Networks

Practical throughput analysis for two-hop wireless network coding

Network coding (NC) has been regarded as a promising technology for throughput improvement in wireless networks, so a thorough understanding on the possible throughput gain from using NC is essential for the application of such technology. Available studies of throughput gain from NC, which mainly focus on only coding sub-layer or both MAC layer and coding sub-layer but largely neglect the primary impact of physical-layer, may lead to an inaccurate (or even qualitatively incorrect) estimation of possible coding gain. To have a more thorough understanding on the practical throughput gain of NC, this paper explores the possible coding gain in the typical two-hop wireless relay network with a careful consideration of interactions among physical layer, MAC layer and coding sub-layer. We first develop an embedded Markov chain theoretical framework to capture the complicated interactions among physical layer, MAC layer and coding sub-layer, based on which the close-form expression of throughput is then derived. We further explore the optimal bandwidth allocation problem in relay nodes for throughput maximization, and also provide a coding condition to clarify the scenarios where network coding does improve the throughput. Our analysis indicates that network coding may actually degrade throughput under some scenarios that were misjudged as being beneficial by previous studies without a careful consideration of primary impact of physical-layer.

On Secure Wireless Communications for Service Oriented Computing

Two-hop wireless network serves as the basic net-work model for the study of general wireless networks, while cooperative jamming is a promising scheme to achieve the physi-cal layer security. This paper establishes a theoretical framework for the study of eavesdropper-tolerance capability (i.e., the exact maximum number of eavesdroppers that can be tolerated) in a two-hop wireless network, where the cooperative jamming is adopted to ensure security defined by secrecy outage probability (SOP) and opportunistic relaying is adopted to guarantee relia-bility defined by transmission outage probability (TOP). For the concerned network, closed form modeling for both SOP and TOP is first conducted based on the Central Limit Theorem. With the help of SOP and TOP models and also the Stochastic Ordering Theory, the model for eavesdropper-tolerance capability analysis is then developed. Finally, extensive simulation and numerical results are provided to illustrate the efficiency of our theoretical framework as well as the eavesdropper-tolerance capability of the concerned network from adopting cooperative jamming and opportunistic relaying.

Special Issue on: Cooperative and Distributed Wireless Communications

Recent advances in radio technology as well as in hardware and software design have resulted in new possibilities for future mobile communication networks. Among those, cooperative communications among the peer nodes of a cellular network could create much anticipated improvement in coverage and capacity of the cellular systems. Such cooperation would generate a distributed network topology where the abundant processing power and storage capacity of the nodes can be shared for carrying out complex tasks. Distributed wireless communications would also enable mobile computing within the mobile cloud. In this context, the 23rd Annual Symposium on Personal Indoor and Mobile Radio Communications (PIMRC 2012) served as a major international telecommunication forum for researchers and technologists to discuss original contributions and results in all fields of personal, indoor and mobile communication systems, including those related to the above topic of cooperative and distributed wireless communications. This special issue is based upon a selection of a very limited number of papers presented at IEEE PIMRC2012. Authors of the top 15 papers from the symposium were invited to submit an extended version of their papers to this special issue. Among those, we are happy to present you with four papers that have been accepted after a rigorous peer review process. The first paper, New Diversity Combining Receivers for Cooperative Multiplexing in Wireless Multiuser Relay Networks, by Chang Kyung Sung, Iain B. Collings, Maged Elkashlan, and Phee Lep Yeoh, proposes two new diversity combining receivers that support cooperative multiplexing in two-hop wireless multiuser relay networks. Cooperative multiplexing has the potential to double the achievable throughput by allowing the base station (BS) and the relay station (RS) to transmit to different users at the same time in the second time slot of the half time division duplexed (TDD) relay transmission. This throughput improvement comes at a cost of performance degradation due to interuser interference between the BS and the RS. To overcome this degradation, two new receivers for the relay-link users are proposed: (1) cooperative multiplexing optimum combining (CMOC) and (2) cooperative multiplexing selection combining (CMSC). Exact closed-form expressions are derived for the moment generation function, probability density function, and the cumulative distribution function of the output SINR, and new analytical expressions for the outage probability, symbol error rate, and achievable throughput are presented. The authors show that the symbol error rate performance and achievable throughput were notably improved relative to the standard single-channel receiver in the high interference regime. The second paper, Improving Cooperative Transmission Feasibility by Network Reconfiguration in Limited Backhaul Networks, by Martin Draxler, Thorsten Biermann, and Holger Karl, develops a mixed integer linear program (MILP) and a BS selection heuristic for Coordinated MultiPoint (CoMP) that takes into account both aspects of the wireless channels and the backhaul network status. This heuristic can also identify which bottlenecks in the A. Jamalipour (&) University of Sydney, Sydney, NSW, Australia e-mail: a.jamalipour@ieee.org

New Diversity Combining Receivers for Cooperative Multiplexing in Wireless Multiuser Relay Networks

We propose two new diversity combining receivers that support cooperative multiplexing in two-hop wireless multiuser relay networks. Cooperative multiplexing has the potential to double the achievable throughput by allowing the base station (BS) and the relay station (RS) to transmit to different users at the same time in the second time slot of the half time division duplexed (TDD) relay transmission. This throughput improvement comes at a cost of performance degradation due to inter-user interference between the BS and the RS. To overcome this degradation, we propose two new receivers for the relay-link users: (1) cooperative multiplexing optimum combining (CMOC) and (2) cooperative multiplexing selection combining (CMSC). The proposed CMOC receiver combines the signals in the first and second time slot of the half TDD transmission such that the output signal-to-interference-plus-noise ratio (SINR) is maximized. The proposed CMSC receiver allows the relay-link user terminal to be active in only one of the two half TDD time slots. As such, CMSC offers power savings relative to CMOC. New insights are drawn from our exact closed-form expressions that we derive for the moment generation function, probability density function, and the cumulative distribution function of the output SINR. Based on these, we present new analytical expressions for the outage probability, symbol error rate, and achievable throughput. Our results show a 3.5 times improvement in the achievable throughput relative to the standard single-channel receiver in the high interference regime.

Throughput analysis of two-hop wireless networks with network coding

A Two-hop Wireless Network (TWN) is the basic topology structure that provides network coding opportunity for improving throughput. Network coding on a homogeneous TWN, in which all the data flows have the same packet size and all the links have the same transmission rate, has been extensively investigated. In this paper, network coding on more practical heterogeneous TWNs, featured by various packet sizes and transmission rates, is studied. Based on the Markov model, the throughput of the proposed network coding scheme, together with the throughput gain, is derived, which matches the simulation results very well. Numerical analyses indicate that, encoding the packets with close size and close transmission rate and enlarging buffer size at the relay node help in improving the throughput gain.

Performance analysis of multiple-antenna cooperative networks under Weibull fading

In wireless communications, cooperative relaying is well-known to enhance the overall system performance, but implementation and cost constraints stand against its wide deployment. This paper investigates the performance of cooperative relays with and without multiple antennas under independent and identically distributed (i.i.d.) Weibull faded channels in a two-hop wireless network. We consider the Weibull fading channel model due to its flexibility in describing the radio propagation environment more than the classical Rayleigh model. Our study relies on applying selection combining (SC) along with threshold decode and forward (TDF) protocol at the cooperative relays as a good compromise between cost and performance. In addition, maximal ratio combining (MRC) is used at the destination. We derive analytical expressions for the end-to-end (E2E) error performance of the network under such scenario and provide simulation results to confirm the validity of the obtained analytical expressions.