Olakunle Elijah

A Comprehensive Survey of Pilot Contamination in Massive MIMO—5G System

Massive MIMO has been recognized as a promising technology to meet the demand for higher data capacity for mobile networks in 2020 and beyond. Although promising, each base station needs accurate estimation of the channel state information (CSI), either through feedback or channel reciprocity schemes in order to achieve the benefits of massive MIMO in practice. Time division duplex (TDD) has been suggested as a better mode to acquire timely CSI in massive MIMO systems. The use of non-orthogonal pilot schemes, proposed for channel estimation in multi-cell TDD networks, is considered as a major source of pilot contamination in the literature due to the limitations of coherence time. Given the importance of pilot contamination in massive MIMO systems, we provide an extensive survey on pilot contamination, and identify other possible sources of pilot contamination, which include hardware impairment and non-reciprocal transceivers. We review established theories that have analyzed the effect of pilot contamination on the performance of massive MIMO systems, particularly on achievable rates. Next, we categorize the different proposed mitigation techniques for pilot contamination using the following taxonomy: pilot-based approach and subspace-based approach. Finally, we highlight the open issues, such as training overhead, deployment scenario, computational complexity, use of channel reciprocity, and conclude with broader perspective and a look at future trends in pilot contamination in massive MIMO systems.

Mitigating pilot contamination in massive MIMO system — 5G: An overview

5G, a future generation cellular networks is expected to meet the increasing demand of continuous growing mobile users and the emergence of services such as internet of things (IoT), machine-to-machine communication (M2M). Massive MIMO has been identified as a promising technology that offers orders-of-magnitude improvements in spectral-efficiency over 4G technologies. However, one of the major limiting factors is pilot contamination when TDD protocol is considered. Different methods have been proposed in literature to mitigate effect of pilot contamination in multi-cellular systems. This paper provides an overview of the proposed approaches in mitigating the effect of pilot contamination in massive MIMO systems. First, we classify the methods proposed under two categories: pilot-based approach and subspace-based approach. We examine the problems of pilot contamination and open issues are discussed.

A Proposed Framework for Massive MIMO Simulation Platform - 5G Systems

The study on 5G massive MIMO (maMIMO) systems has garnered a lot of research interest. Several research works are ongoing and some of which include, the development of mathematical models, performance evaluation, algorithm development and basic prototyping work. However, the framework for a unified simulation platform and methodology has not been established. The need for a massive MIMO simulation platform that can be used for comparative study and analysis purpose of different deployment scenarios of maMIMO systems is envisaged. Hence, in this paper, a framework for massive MIMO simulation platform (MMSP) for 5G cellular systems is proposed. To achieve this, key research areas related to massive MIMO were identified from the literature and a taxonomy which consists of three non-overlapping branches: (1) System configuration, (2) System processing and (3) System analysis is advocated. Preliminary results are presented using a developed prototype from the proposed framework.

EMF Radiation Effects from 5 × 5 Dipole Array Antenna Towards Human Body for 5G Communication

Electromagnetic Field (EMF) is defined as a physical field produced by electrically charged objects. Nowadays there is an extensive concern about the EMF radiation effects towards human body. In this paper, the effect of EMF radiation is studied using a single dipole and 5 × 5 array dipole antennas. The proposed antenna is designed and simulated by using FEKO software. Results and discussions are explored to scrutinize the EMF performance of the antenna particularly on the distance and the frequency of the antenna with respect to the human body. Subsequently, the results of the SAR and power density at various frequency and distance are presented. It is shown that SAR and power density increases as the frequency increases at a fixed distance. The result of power density for the array antenna at different distances is also presented.

On the sparsity-aware partial-update NLMS algorithms for UWB channel estimation

Partial updating of filter coefficients is an effective method for reducing computational load and power consumption in adaptive filter implementation. In this paper, we present a class of MMax partial update NLMS algorithms suitable for estimating UWB channels, whose characteristics have shown to vary between highly sparse and dense depending on the channel environment under consideration and the measured bandwidth. Simulation results show improved performance of the proposed algorithms in terms of convergence speed, and computational complexity.

Simulation of DVB-T2 integrated receiver decoder specifications for ASEAN countries

DVB-T2 (digital video broadcasting - second generation terrestrial) is considered as the most advanced digital terrestrial television system. It supports either or any combination of SD (standard definition), HD (high definition) UHD (ultra-high definition), and mobile TV. One of the challenges of the DVB-T2 is the many options it provides in system mode and parameters which needs to be accurately selected to suit different applications. In view of this, requirement for the IRD (integrated receiver decoder) for use with the DVB-T2 for ASEAN countries has been defined. This paper deals with the transmission performance for the AGWN (additive white Gaussian noise), fixed and portable TV channels. Simulation results of the BER (bit error ratio) after the FEC (Forward Error Correction) decoding were evaluated and compared for the three types of channels. The effect of constellation rotation is being explored for a particular IRD scenario. Appropriate simulations for this study were carried using common simulation platform (CSP) and MATLAB. Finally, the achieved results are evaluated and clearly discussed.

Design of ka band downlink radial line slot array antenna for direct broadcast satellite services

Ka-band is an emerging band for future satellite operators because of the increase in demand for capacity, availability as well as its applicability for broadband services. This submission attempts the implementation of the Ka-band (21.4 - 22.0) GHz Radial Line Slot Array (RLSA) antenna design using CST MWS 2013. Simulations results are presented and compared with the Ku-band DBS receive (12.25 - 12.75) GHz in terms of bandwidth availability, return loss and directivity.