The worldwide acceptability of wireless communication is due to its portability and flexibility. However, its performance is governed by the multipath propagation effects which make wireless communication modelling challenging. The existing technique being used to solve this propagation effects is based on Probability Density Function (PDF) which is inefficient in addressing diversity over combined Rayleigh and Rician (C_(Ray-Ric)) fading due to its complexity. Therefore, this paper aims to develop an approximated Moment Generating Function (MGF) for spatial diversity combining such as Equal Gain Combining (EGC) and Maximal Ratio Combining (MRC) over C_(Ray-Ric) fading channel. A MGF model in form of Taylor’s series is generated from the expected value of the C_(Ray-Ric) fading channels. The MGF is characterized using Amount of Fading (AF) and Bit Error Rate (BER) in term of Line of Sight (LOS) component ‘k’. The MGF is transformed into EGC and MRC, and were measured in terms of propagation paths (L). These are approximated using the Pade ́ Approximation (PA). The approximates obtained are used in the derivation of BER expression of M-ary Quadrature Amplitude Modulation (MQAM) and M-ary Phase Shift Keying (MPSK) in terms of Signal to Noise Ratio (SNR). The models are evaluated using AF and BER at different values of LOS to determine the performance of the diversity techniques. The results obtained show that as LOS component ‘k’ increases from 0, the Af and BER reduce indicating reduction in fading effects. Therefore, the models developed are effective in predicting the performance of diversity techniques and overcome the multipath effects associated with the wireless communication.

Wireless communication system is of paramount importance in the world of telecommunication infrastructure and is expected to be a leading role in the development of a nation. However, the system is characterized by multipath propagation effects that lead to variability of the received signal thereby degrading the performance. Equal Gain Combiner (EGC) being used to address this problem is associated with hardware complexity that results in long processing time, while Threshold Combiner (TC) with low processing time has poor performance. Hence, in this paper, a hybridized Diversity Combiner (DC) consisting of EGC and TC, (TC-EGC) with a closed form expression over Nakagami fading channel is developed. TC-EGC is derived using the conventional EGC and TC at the receiver. Randomly generated bits used as source data are modulated using M-ary Quadrature Amplitude Modulation (M-QAM) and transmitted over Nakagami channel after filtering. The faded signals generated at varying paths ‘L’ (2, 3, 4) are scanned by TC to select the strongest paths. The outputs from the three TCs are combined by EGC to obtain the received signal which is converted to baseband through demodulation. A mathematical expression using the Probability Density Function (PDF) of Nakagami fading channel at varying paths ‘L’ for Outage Probability (OP) is also derived. The technique is simulated using Matrix Laboratory (version 7.2). The performance is evaluated using Signal-to-Noise Ratio (SNR), Outage Probability (OP) and Processing Time (PT). The study shows that the TC-EGC gives lower OP and PT values when compared with conventional EGC and TC, with reduction in hardware complexity. The TC-EGC developed can be used to enhance the performance of wireless communication system.

Spectrum sensing is of paramount importance in the Cognitive Radio Network (CRN) due to massive spread of wireless services. However, spectrum sensing in CRN is affected by multipath effects that make detection difficult. Square- Law Combining (SLC) technique, which is one of the methods previously used to address this problem, is associated with hardware complexity that results in long processing time. Hence, this paper aim to modify SLC technique for primary user detection in the CRN. The modified model consists of three Secondary User (SU) antennas which receive the faded signals through the Rayleigh fading channel. The received signals are combined using Switch Combiner (SC) at Radio Frequency (RF) stage. The selected signal passes through only one Energy Detector (ED) before making decision. The modified model is incorporated into simulation model which consists of Primary User (PU) transmitter that processes the randomly generated data through some signal processing techniques for transmission to the SU receiver. Probability of False Alarm (PFA) expression is derived for the modified Square-Law Combiner (mSLC) to set the thresholds at 6.64 and 9.14 for PFA of 0.01 and 0.02, respectively. The modified model is evaluated using Probability of Missing (PM), Probability of Detection (PD) and Processing Time (PT) to determine the performance. The results of the mSLC show that at SNR of 4 dB and PFA of 0.01, the values obtained for PD, PM, PT are 0.6575, 0.3530, 5.5540 s, respectively, as against the conventional SLC of 0.4000, 0.600, 6.2055 s, respectively. At SNR of 4 dB and PFA of 0.02, the values obtained for the mSLC are 0.7600, 0.3457, 6.1945 s for PD, PM and PT, respectively, as against 0.4000, 0.6000, 7.2197 s for conventional SLC. The results show that mSLC gives lower PM, higher PD and lower PT values when compared with conventional SLC.