The Turbo decoding performance will suffer serious degradation under low signal-to-noise ratios （SNR） conditions for the reason of residual frequency and phase offset in the carrier. In this paper, an improved resid...The Turbo decoding performance will suffer serious degradation under low signal-to-noise ratios （SNR） conditions for the reason of residual frequency and phase offset in the carrier. In this paper, an improved residual carrier frequency offset estimation algorithm based on a priori probability aided （APPA） phase estimation is proposed. A carrier synchronization loop that combines the iterative turbo decoder and the phase estimator together is constructed, where the extrinsic information obtained from the Turbo decoder is used to aid an iterative phase estimation process. The simulation results show that the algorithm performs successfully under very low SNR conditions （for example, less than -7.4 dB） with large frequency offset and phase error and the performance of this algorithm is very close to the optimally synchronized system.展开更多
Neighbor discovery is important for docking applications,where mobile nodes communicate with static nodes situated at various rendezvous points.Among the existing neighbor discovery protocols,the probabilistic methods...Neighbor discovery is important for docking applications,where mobile nodes communicate with static nodes situated at various rendezvous points.Among the existing neighbor discovery protocols,the probabilistic methods perform well in average cases but they have aperiodic,unpredictable,and unbounded discovery latency.Yet,deterministic protocols can provide bounded worst-case discovery latency by sacrificing the average-case performance.In this study,we propose a mobility-assisted slot index synchronization(MASS),which is a new synchronization technique that can improve the average-case performance of deterministic neighbor discovery protocols via slot index synchronization without incurring additional energy consumption.Furthermore,we propose an optimized beacon strategy in MASS to mitigate beaconing collisions,which can lead to discovery failures in situations where multiple neighbors are in the vicinity.We evaluate MASS with theoretical analysis and simulations using real traces from a tourist tracking system deployed at the Mogao Grottoes,which is a famous cultural heritage site in China.We show that MASS can reduce the average discovery latency of state-of-the-art deterministic neighbor discovery protocols by up to two orders of magnitude.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.60602008National 863 Programs under Grant No.2007AA01Z299,2006AA01Z269
文摘The Turbo decoding performance will suffer serious degradation under low signal-to-noise ratios （SNR） conditions for the reason of residual frequency and phase offset in the carrier. In this paper, an improved residual carrier frequency offset estimation algorithm based on a priori probability aided （APPA） phase estimation is proposed. A carrier synchronization loop that combines the iterative turbo decoder and the phase estimator together is constructed, where the extrinsic information obtained from the Turbo decoder is used to aid an iterative phase estimation process. The simulation results show that the algorithm performs successfully under very low SNR conditions （for example, less than -7.4 dB） with large frequency offset and phase error and the performance of this algorithm is very close to the optimally synchronized system.
基金Project supported by the National High-Tech R&D Program of China(No.2012AA101701)the National Key Technology Support Program of China(Nos.2013BAK01B00 and2014BAK16B00)Grotto Temples Digital Protection of Cultural Relics and Equipment Upgrading of National Cultural Heritage Administration Scientific Research Institutes
文摘Neighbor discovery is important for docking applications,where mobile nodes communicate with static nodes situated at various rendezvous points.Among the existing neighbor discovery protocols,the probabilistic methods perform well in average cases but they have aperiodic,unpredictable,and unbounded discovery latency.Yet,deterministic protocols can provide bounded worst-case discovery latency by sacrificing the average-case performance.In this study,we propose a mobility-assisted slot index synchronization(MASS),which is a new synchronization technique that can improve the average-case performance of deterministic neighbor discovery protocols via slot index synchronization without incurring additional energy consumption.Furthermore,we propose an optimized beacon strategy in MASS to mitigate beaconing collisions,which can lead to discovery failures in situations where multiple neighbors are in the vicinity.We evaluate MASS with theoretical analysis and simulations using real traces from a tourist tracking system deployed at the Mogao Grottoes,which is a famous cultural heritage site in China.We show that MASS can reduce the average discovery latency of state-of-the-art deterministic neighbor discovery protocols by up to two orders of magnitude.
