Using LDPC coding and AMC to mitigate received power imbalance in carrier aggregation communication system

Abstract

When a carrier aggregation communication system suffers from receiving power imbalance (RPI) in its antenna array due to design flaw, operator's negligence etc. the system performance may be degraded to an unacceptable level. Specifically in this paper a carrier aggregation communication system with two carrier links while one link suffers RPI is considered, various modulation techniques, such as QPSK, 16 QAM and 64 QAM and/or coding schemes, Convolution Code (CC) and Low Density Parity Check Code (LDPC) are implemented in the system performance simulation to investigate the system behavior when it has the design request to maintain the same system performance in each link when the RPI has values of 7 or 10 dB.

Using turbo iterative receiver to mitigate RPI effect in MIMO OFDM communication system

“…(1) the relation between the received signal y[p, k] ∈ C Nrx that is resulted from removing the CP and passing through the fast Fourier transform (FFT) block and the transmitted signal x[p, k] ∈ Ω Ntx for the pth OFDM symbol and kth subcarrier, the matrix of the channel frequency response H[p, k] ∈ C NrxNtx [1,5] and the RPI effect, denoted as ΔG [3,4] can be expressed as in Eq. (1)…”

“…System bandwidth of 1.4 MHz is adopted in the simulation. When the system suffers various levels of RPI effect then a LDPC code with code rate 1/2 or a (2, 1, 6) Convolution code (CC216) with code rate 1/2 is used as the channel coding, and also in LDPC decoding it performs 16 iterative operations within the LDPC channel decoder [3]. When the allowable BER in the system is set less than 10 −3 , the simulation results are listed in Table I for the required SNR in our proposed turbo iterative receiver with either LDPC or CC216 decoder is cascaded with the MOD and the turbo iteration number between MOD and channel decoder varies from 0 to 3 for the RPI effect in the MIMO OFDM communication system has the range from −10 dB to 0 dB.…”

“…However according to literature [3,4], the received power imbalance (RPI) effect, which is caused by design flaw or user's negligence, may exist at the multiple antennas receiver in MIMO wireless communication. This RPI effect can vary in a wide range from −10 dB to 0 dB and its effect may exhibit in burst pattern; and consequently when it occurs the channel estimator may not have the capability to mitigate or conquer this effect and the system performance may be degraded seriously.…”

Performance Analysis With Coordination Among Base Stations for Next Generation Communication System

“…After the user is inter-connected by these base stations and through the implementation of the coordination among these base stations, the user's effective receiving gain can be increased, and also the interference among users can be reduced by implementing the techniques such as Coordinated Multi-input Multioutput (Co-MIMO) and Coordinated Multiplexing (CoMP) [1][2][3][4][5][6][7].…”