Cui Gaofeng

A centralized iterative water filling algorithm in coordinated multipoint OFDMA network

In the wireless mobile communication system, the performance of system throughput is seriously affected by the interference, which can be divided into intra-cell and inter-cell interference. Intra-cell interference could be refrained by orthogonal frequency-division multiple-access (OFDMA). Coordinated multipoint (CoMP) transmission is an effect way to decrease inter-cell interference. A CIWF algorithm is proposed to maximize the system throughput subjected to per-BS power constraint (PBPC) in the downlink OFDMA cellular network supporting CoMP transmission. In this algorithm, co-channel users are selected and the power allocated by per resource block is computed with the confirmation of an analytical derivation. Simulation results demonstrate that the proposed algorithm outperforms traditional ones from the aspect of throughput.

Beam Coverage Dynamic Adjustment Scheme Based on Maximizing System Capacity for Multi-beam Satellite Communication System

Multi-beam technique has been widely applied in modern satellite communication systems. However, the satellite power and bandwidth resources are scarce and expensive due to the limitation of satellite platform. Thus it is urgent to utilize the resources efficiently. Meanwhile, due to the disequilibrium of the non-uniform distribution of traffic request and the uniform coverage of satellite beams, the capacity of the overloaded beams may decrease since the lack of resources, while the resource utilization of the under-loaded beams will be insufficient. In order to increase the capacity of the multi-beam satellite communication system and improve the load balancing performance of the system, a beam coverage dynamic adjustment scheme based on maximizing system capacity is proposed in this paper. Theoretical analysis and simulation results demonstrate the correctness and effectiveness of the proposed scheme.

Random access preamble design based on time pre-compensation for LTE-satellite system

Abstract Because of the integration of long term evolution (LTE) technology and mobile satellite communication systems, uplink access technology for LTE-based geo-stationary earth orbit (GEO) satellite has become a popular research topic for satellite system. In order to solve the problem of unreasonable design for physical random access channel (PRACH) signal structure and reduce the effect of time uncertainty, this paper proposes a novel random access preamble based on time pre-compensation (TPC) for LTE-Satellite (LTE-S) system. In this scheme, by applying the method of non-linear least squares, the user terminal (UT) can use the receiving power to estimate the communication round trip delay (RTD) and based on the transmission delay of the beam center and the satellite, RTD can be compensated before transmission. Therefore, the preamble length and duration can be reduced without related to the maximum of RTD. In order to verify the performance of the scheme, the MATLAB is used to build a test system. The simulation results show that the proposed preamble satisfies the requirements of LTE-S system, and the better performance than previous researches is obtained.