Yamuna Dhungana Supervisor : Dr. R.M.A.P. Rajatheva May 16, 2011

Motivation Goal Goal of 4G wireless Network : to offer high data rate and high quality of service anytime, anywhere Condition Condition : Such network can cover any geographical area by either using terrestrial network or satellite network Solution Solution : Integration of terrestrial and satellite networks into a hybrid architecture forming Hybrid Satellite/Terrestrial Network This thesis proposes … terrestrial relay node assisted cooperative communication approach towards Hybrid Satellite/ Terrestrial network

Satellite Communications voice, data, video and networking services through large, expensive, high-power earth station transmitters communicating via geostationary satellites provides services through low earth-orbit (LEO) and medium earth orbit (MEO) satellites directly communicating with lower power mobile user terminals Works like terrestrial cellular communication Earth station (ES) Transmitter Traditional satellite communication Land mobile satellite (LMS) communication

Relay Assisted Cooperative Communicat ion a collaborative communication in which a relay station helps to forward information between source and destination Major Relay protocols –Amplify and Forward(AF) –Decode and Forward(DF) S R D  Improves transmission reliability through diversity

Proposed System: Basic Model Applies the concept of relay transmission to LMS communication Implements through a terrestrial relay node forwarding information between satellite and land mobile user terminal Develops a form of Hybrid Satellite/ Terrestrial Network

Demonstration of relaying concept in LMS communication

Advantages  Brings satellite coverage indoor or in tunnels Link not available due to heavy shadowing  Can serve low cost user terminal with no satellite transmission/ reception capab ilities  Serves as spatial diversity technique in mitigating the blockage effect in LMS channels  Support terrestrial networks unable to provide their services (e.g., because of lack of coverage, emergency situations, network overloads)

Proposed System: Enhanced Model The basic relaying concept in LMS communication is enhanced through the incorporation of multiple antennas at all the three terminals. Transmitter.... Receiver Single Antenna SystemMultiple input multiple output (MIMO) system MIMO system offers  Enhanced throughput  Increased transmission reliability  MIMO relaying technology A new paradigm with tremendous potential Already proposed as a next major extension of IEEE WiMAX

Satellite Channel Model LMS communication suffers from strong variations of the received signal power due to signal shadowing and multipath fading. Signal shadowing by obstacles in the propagation path (e.g. buildings, trees, etc.) results into attenuation of the signal power over the entire bandwidth. Proper modeling of such phenomena is important for performance evaluation. In this thesis, LMS link is modeled with Shadowed Rician fading model which accounts for both line- of-sight (LOS) random shadowing and multipath fading.

System configurations proposed for implementation Configuration I: Source (S) Relay (R).. Destination (D).... Transmit Beamforming Receive Beamforming NsNs NrNr NdNd Selected Antenna H SR h RD The configuration is analyzed  Under both AF and DF relaying  Considering both uncorrelated and correlated antennas

Configuration II: OSTBC encoder Fixed gain Amplifier OSTBC decoder H1H1 H2H2 Satellite (S) Terrestrial Relay node (R) 1 NsNs 1 NrNr 1 NrNr 1 NdNd Noise whitening filter Mobile Station (D)

Results and Discussions: Configuration I Average SER of AF and DF system using QPSK modulation for antenna configuration (N s,N r,N d ) Average SER of AF system for antenna configuration (N s,N r,N d ) in different correlation scenarios

Results and Discussions: Configuration II Average SER of BPSK and 4PAM constellations using Alamouti’s coding for antenna configuration (N s,N r,N d )

Summary An approach to hybrid satellite/terrestrial network towards the achievement of ambitious coverage requirement of 4G networks is proposed. The proposed concept is complemented with MIMO technology. MIMO system is found to have significant performance gains over single input single antenna (SISO) system. Two different system configurations are proposed for MIMO relaying concept implementation in LMS communica tion.

Future Research Feasibility and performance analysis in multiple relay environment. Assessment of advantages and drawbacks of relaying characteristics of infrastructure based fixed relays or mobile devices carried by subscribers.

List of Publications Conference Publication Yamuna Dhungana and Nandana Rajatheva, “Analysis of LMS based dual hop MIMO systems with beamforming,” in Proc. IEEE Int. Conf. on Commun. (ICC2011), accepted for publication. Journal Publications Yamuna Dhungana and Nandana Rajatheva, “Impact of antenna correlation on LMS based dual hop MIMO systems with beamforming,” IEEE Trans. Wireless Commun., submitted for publication. Yamuna Dhungana and Nandana Rajatheva, “Dual Hop MIMO OSTBC for LMS Communication,” IEEE Commun. Letter., submitted for publication.

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