Mutually Interfering Relay Channels

1. Towards Harnessing Relay Mobility in MANETs Rohit Naini, Pierre Moulin - University of Illinois, Urbana-Champaign Introduction Relay Channel as part of a MANET Mutually Interfering Relay Channels • The relay channel with single interferer though a good starting point , yields simplistic solutions. • An actual Adhoc Network could potentially have several interfering transmissions. Locations Should be Jointly Optimized Relay Relay Sensors (Accelerometers) Processing Module Mobile Relays • Sensors measure • user activity • Convert activities • to calories burnt Source Destination Source Compress and Forward rate vs Relay Position Calculations Log on PDA • Mobility should be viewed as a resource in an Adhoc Network • Exploring the potential held by mobility in a Relay Channel can provide valuable insights for larger networks optimal location Source Destination Destination • This problem introduces aspects such as inter-nodal cooperation in different parts of the network. • The joint-mobility of several nodes entitles a multiple objectives game-theoretic approach. • Solving this problem would give valuable insight into interaction between coexistent non-cooperating network blocks Source Relay Position- Angular Relay Position radial Destination • The transmissions from rest of the network are assumed to be from unknown Gaussian codebooks • Correlation between noises at Relay and Destination are computed based on Relay position with respect to the position of interfering nodes. • The throughputs of the three relay schemes are evaluated by varying the relay location Interferer Locations – (0.7,45),(0.7,72),(0.7,135) Relay Channel with Single Interferer • Relay Channel capacity is unknown but surrogate performance metrics can be used: • Cut-set Bound • Decode-Forward Rate • Compress Forward Rate • A Gaussian Channel model is employed with a corrected quadratic path loss • External Interferer emits Gaussian signal with an unknown codebook • Subject to mobility restrictions, optimal relay location/scheme can be chosen Conclusion and Future Directions Simulation Analysis and Discussion • Interference management holds the key to improving Adhoc Network performance • Mobility can be used to minimize the malicious impact of interference between the different parts of the network • The usually sub-optimal Compress-Forward scheme proves helpful in a system marred with a high degree of interference • Future Directions • Understand the role of mobility in other adhoc network blocks. • Devise mobility strategies for cooperative multi-hop relaying • The optimal relay locations vary significantly based on the scheme being used • For a Decode-Forward scheme, it is optimal for the relay to relocate itself away from the Interfering nodes • For a Compress-Forward scheme, relay should relocate itself to a point with higher interference reception and good correlation to Destination’s Noise • Compress-Forward scheme exploits the noise correlation to allow cooperation between the Relay and Destination • Compress-Forward is well suited when there is a relatively close interfering node with high power Node Polar Co-ords Source (0,0) Destination (1,0) Interferer (0.5,45) Compress-Fwd Cut Set Bound Decode-Fwd