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It is expected that next-generation wireless networks will provide a plethora of mobile wireless services to users and ubiquitous network coverage at all times. Meeting these expected goals requires that new and existing networks be seamlessly integrated together to form Heterogeneous Wireless Networks (HWNs). Thus, seamless and efficient handover mechanisms are pertinent for optimal network performance in HWNs; so that the mobile user can switch from one access network to another, in search of the best connection for the demanded services. The HWNs' performance can be reduced, if efficient network selection is not achieved. In HWNs, network-selection decisions can be evaluated by using multi-criteria, or a single criterion. However, network selection and decision-making in HWNs often involves taking into account a large number of complex and conflicting network-decision factors, or criteria. Thus multi-criteria decision-making techniques are more efficient than single-criterion techniques. Multi-Criteria Decision-Making (MCDM) techniques comprise of a developed branch of operational research for assisting in the resolution of complex decision-making problems. MCDM is an important tool that has been used to model and analyze handover-decisions and network-selection problems in HWNs. This paper reviews and classifies the most significant MCDM algorithms that have been used to address the network decision-making problems in HWNs in terms of algorithmic approach, the type of calls, the cardinality of decision criteria employed, handover-control points and the types of network utilities. Comprehensive step-wise mathematical implementations of the reviewed MCDM schemes are presented, while pointing out their strengths and limitations. This paper review fills a research gap in the investigation on network-selection criteria's interdependence and interactions, and their effects on criteria's weight of importance. It then provides an insight into the importance of network-criteria weighting and the current research trend in the application of MCDM algorithms to network-selection problems in HWNs. [ABSTRACT FROM AUTHOR]

The Orthogonal Frequency Division Multiplexing (OFDM) method provides effective bandwidth utilization and straightforward Frequency Domain Equalization (FDE). The OFDM system can be applied without a group of modulators and demodulators by using the Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT). The Fast Walsh Hadamard Transform (FWHT) and Inverse Fast Walsh Hadamard Transform (IFWHT) can also be used to build the OFDM system. In this work, we employ the IFWHT and FWHT to build the OFDM. This is followed by a proposal for a Joint Low-Complexity Regularized Zero Forcing-Successive Interference Cancellation (JLCRZF-SIC) equalizer with respect to various linear and nonlinear equalizers at various antenna configurations. A closed form for arithmetic operation count for the proposed equalizer is proposed. The proposed equalizer executes the equalization process more accurately than other schemes with low-complexity deployments. The analysis results show that the proposed equalizer outperforms the conventional one. [ABSTRACT FROM AUTHOR]