Performance Evaluation of Spatial Multiplexing MIMO Systems with Various Detection Schemes

Spatial Multiplexing (SM) over multiple-input multiple output (MIMO) channels significantly improves the data rates over wireless channels. The challenge is to design low complexity and high performance algorithms that capable of accurately detecting the transmitted signals. In this paper, the general model of MIMO communication system was introduced in addition to several MIMO Spatial Multiplexing (SM) detection techniques. The Bit Error Rate (BER) performance and computational complexity of Minimum Mean Square Error (MMSE), Zero Forcing (ZF), and Maximum Likelihood (ML) detection schemes have been analyzed and compared to each other using Matlab R2009b. Results of simulation illustrates that their performances of MMSE and ZF detectors are close together and need more than 14 dB of Signal to Noise Ratio (SNR) to achieve 10-4 BER. On the other hand ML detector shows better results than MMSE and ZF detectors but the complexity and the delay are large. Been proposed to install the number of transmitter antennas fixed on 2 and change receiving antennas 2, 3, and 4. Results showed that the present proposal came close to the results of the previous model, but less complexit

Evaluation of Low Density Parity Check Codes Over Various Channel Types

Low density parity check (LDPC) codes are one of the best error correcting codes in today’s coding world and are known to approach the Shannon limit. As with all other channel coding schemes, LDPC codes add redundancy to the uncoded input data to make it more immune to channel impairments. In this paper, the impact of low-Density Parity-Check code (LDPC) on the performance of system under Binary Phase Shift keying (BPSK) over an Additive White Gaussian Noise (AWGN) and other fading (Raleigh and Rician) channels is investigated. Obtained results show that LDPC can improve transceiver system for various channel types. At Bit Error Rate (BER) of 10-4 such code with code rate of ½ reduces the Signal to Noise Ratio (SNR) by range of 6.5 to 9 dB for fading channels in contrast to uncoded system. By studying modern research it has been found that turbo code can achieved same manner but LDPC decoder faster than turbo decoder and can be implemented in parallel

Log-Likelihood Ratio to Improve Hard DecisionViterbi Algorithm

Hard decision of Viterbi decoder suffer from the need of high Signal to Noise Ratio (SNR) to achieve reasonable Bit Error Rate (BER). For the purpose of improving the efficiency of its performance, it must increase the constraint length of the code, in this case highlights the problem of complexity in the structure. Several methods are used to solve this problem. In this paper the Log-Likelihood Ratio (LLR) with 3 bit soft decision and unquantized scheme has been implemented with simple transceiver using Convolutional codes. Results are achieved using the last version of Matlab (R2011b) illustrates that such scheme 2.7 dB over conventional system. In addition it has been examine such system with increasing the speed of data rate to double, the results of simulation confirm that it need 7 dB to achieve 10-6 BER

Design and implementation of log domain decoder

Low-Density-Parity-Check (LDPC) code has become famous in communications systems for error correction, as an advantage of the robust performance in correcting errors and the ability to meet all the requirements of the 5G system. However, the mot challenge faced researchers is the hardware implementation, because of higher complexity and long run-time. In this paper, an efficient and optimum design for log domain decoder has been implemented using Xilinx system generator with FPGA device Kintex 7 (XC7K325T-2FFG900C). Results confirm that the proposed decoder gives a Bit Error Rate (BER) very closed to theory calculations which illustrate that this decoder is suitable for next generation demand which needs high data rate with very low BER

Human body blockage effect on wireless network performance for outdoor coverage

The rapid development in the field of communications and growing numbers of the population every year stimulate telecommunications companies to develop communications systems to accommodate all users. In this paper, we will study the blockage effect of the student body on the propagation of the signals in the external wireless network. We took various numbers of the student density on the campus to know the extent it affects especially in crowded environments. The student body structure and buildings are designed in the college according to the real dimensions by Wireless InSite software. We compared scenarios for the different numbers of student density, we noticed that whenever an increase in the student density in the college will lead to increased path loss and delay spread time. In addition, note there is a gradual decrease in the received power (RP) if there is no student density highest RP is -28.2 dBm, when there are 300 students highest RP is -34.7 dBm, and when there are 600 students highest RP is -36.5 dBm. The reasons are that signals path spread inside the college will be passing through several collisions whether student body blockage or buildings that are built from different materials