On Security and Reliability using Cooperative Transmissions in Sensor Networks

Recent work on cooperative communications has demonstrated benefits in terms of improving the reliability of links through diversity and/or increasing the reach of a link compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide such benefits using space-time coding. In a multi-hop sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node, which will use its neighbors and so on to reach the destination. For the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions. However, the presence of malicious or compromised nodes in the network impacts the use of cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions may fare better or worse than SISO transmissions

On Security and reliability using cooperative transmissions in sensor networks

Cooperative transmissions have received recent attention and research papers have demonstrated their benefits for wireless networks. Such benefits include improving the reliability of links through diversity and/or increasing the reach of a link compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide diversity gain or range improvement using space-time coding. In a multi-hop ad hoc or sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node with greater reliability or at a larger distance than otherwise possible. The intermediate node will use its neighbors in a similar manner and this process continues till the destination is reached. Thus, for the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions as each hop spans a larger distance. However, the presence of ma-licious or compromised nodes in the network impacts the benefits obtained with cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. However, the relationships between the number of relays, the number of hops, and success probabilities are not trivial to determine. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions fare better or worse than SISO transmissions. We take into consideration additional parameters such as the path-loss exponent and provide a framework that allows us to evaluate the conditions when cooperative transmissions are better than SISO transmissions. This analysis provides insights that can be employed before resorting to simulations or experimentation. © Springer Science+Business Media, LLC 2012

Mobile Jammers for Secrecy Rate Maximization in Cooperative Networks

We consider a source (Alice) trying to communicate with a destination (Bob), in a way that an unauthorized node (Eve) cannot infer, based on her observations, the information that is being transmitted. The communication is assisted by multiple multi-antenna cooperating nodes (helpers) who have the ability to move. While Alice transmits, the helpers transmit noise that is designed to affect the entire space except Bob. We consider the problem of selecting the helper weights and positions that maximize the system secrecy rate. It turns out that this optimization problem can be efficiently solved, leading to a novel decentralized helper motion control scheme. Simulations indicate that introducing helper mobility leads to considerable savings in terms of helper transmit power, as well as total number of helpers required for secrecy communications.Comment: ICASSP 201

Resource Allocation for Secure Gaussian Parallel Relay Channels with Finite-Length Coding and Discrete Constellations

We investigate the transmission of a secret message from Alice to Bob in the presence of an eavesdropper (Eve) and many of decode-and-forward relay nodes. Each link comprises a set of parallel channels, modeling for example an orthogonal frequency division multiplexing transmission. We consider the impact of discrete constellations and finite-length coding, defining an achievable secrecy rate under a constraint on the equivocation rate at Eve. Then we propose a power and channel allocation algorithm that maximizes the achievable secrecy rate by resorting to two coupled Gale-Shapley algorithms for stable matching problem. We consider the scenarios of both full and partial channel state information at Alice. In the latter case, we only guarantee an outage secrecy rate, i.e., the rate of a message that remains secret with a given probability. Numerical results are provided for Rayleigh fading channels in terms of average outage secrecy rate, showing that practical schemes achieve a performance quite close to that of ideal ones

Enhancing wireless security via optimal cooperative jamming

In this work, we analyze the secrecy rate in a cooperative network, where a source node is assisted by relay nodes via cooperative jamming for delivering a secret message to the destination in the presence of an eavesdropper node. We consider the availability of both full and partial channel state information (CSI), and we take into account average power limitation at the relays as we formulate the rate maximization problem as a primal-dual problem. We derive the closed form solution for the full CSI case, and we show that the optimal solution allows the transmission of only one relay. For the partial CSI case, we define the concept of secrecy outage, where some of packets are intercepted by the eavesdropper, and we derive the secrecy outage probability and throughput in terms of average channel statistics. Due to the high nonlinearity of the secrecy throughput term, we propose a gradient update algorithm for obtaining the optimal power solutions for the partial CSI case. Our simulations demonstrate the gains of cooperative jamming over direct transmission for both full and partial CSI cases, where it is shown that the secrecy rate of the direct transmission is increased significantly, by %20−%80, when CJ is employed with our optimal power assignment algorithm