Johnny Koh

Energy efficiency and cell coverage area analysis for macrocell networks

The issues of energy efficiency and environmental protection are becoming critical issues for both fixed and wireless network operators worldwide. For wireless network operators, the challenge generally lies on providing maximum energy efficiency with largest possible coverage area. In this paper we first investigate the parameters affecting energy efficiency and the cell coverage area. We later analyze the relationship between area power consumption and transmission range (cell radius), transmission power, frequency band, shadowing and the path-loss exponent. From the analysis, optimal inter site distance that utilizing minimum area power consumption can be obtained for different percentage requirement of coverage area corresponding to minimum transmit power that achieves this degree of coverage. The optimal inter site distance is determined for macrocell without the impact of shadowing to be equal about 1250 m with minimum area power consumption of 526 W/km2. With the effect of shadowing, the optimal inter site distance and minimum area power consumption are 1050 m and 778.7 W/km2 respectively.

Energy efficiency of LTE macro base station

The growing energy consumption in wireless networks driven by dramatic increases in mobile users and network traffic, are putting mobile operators under immense challenges towards meeting the demands of both cost reduction and environment conservation. The network Energy Efficiency (EE) considers not only energy consumed by the base station (BS), but also the capacity and coverage of the network. In this paper we study the impact of modulation and coding schemes (MCS), bandwidth (BW) size and transmitted power on the energy efficiency of a LTE macro base station. Although it is very much expected that higher transmission power results in lower EE, the difference actually diminishes when cell size increases. At around 1200m it is found that the EE are almost equal for all transmission power considered. On the other hand, EE increases significantly as the BW increases. Similar effect on EE is observed when MCS changes from lower order to higher order scheme. In fact EE becomes more sensitive to MCS change at higher bandwidth.

Energy-aware load adaptive framework for LTE heterogeneous network

One of the main approaches for improving the network energy efficiency EE is through the introduction of load adaptive techniques, where the networks components/subsystems are switched off when the network is lightly loaded. Optimising such a dynamic operation in a heterogeneous network HetNet remains an active topic of research. In this paper, a traffic load-adaptive model that aims to evaluate the EE of base stations in Long Term Evolution LTE HetNet is presented. First, a model that simulates the load-adaptive power consumption behaviour of LTE HetNet is developed. In this regard, a load adaptation factor is introduced to assess the networks EE performance. The model also adapts and predicts the achievable data rate of each base station with respect to the traffic load. Our study shows that the fully load-adaptive LTE HetNet can significantly improve networks EE up to 10%, 40%, and 80% for high, medium, and low loads, respectively, as compared to the conventional non load-adaptive HetNet. In addition, we show that the full adaptive network operation can achieve significant EE gains under a realistic daily traffic profile up to 86%. The proposed evaluation model is essential to assess the network EE and can be used in future studies that focus on improving the adaptation level of the already installed network equipments. Copyright ©2014 John Wiley & Sons, Ltd.

Downlink capacity improvement of WCDMA system by using adaptive antenna with novel MDPC beamforming technique

Smart antenna is a well known method to increase the spectral efficiency of the wireless channel and subsequently increase the mobile communication system capacity without jeopardizing the system QoS (De Sousa et al, 2003; Marikar, 2002). There are two major types of smart antenna systems; switch beam antenna and adaptive beam antenna. Adaptive antenna which has dynamic beam to cater for users needs is better in improving the system capacity but requires more advance beam forming algorithm and requires intensive processing power for beam forming. Thus, adaptive beamforming technique is critically important. In this paper, a novel adaptive downlink beam forming technique for WCDMA system namely Minimum Downlink Power Consumption (MDPC) is introduced. A dynamic radio network simulator was developed in Visual C++/spl reg/ to study the power consumption at WCDMA base station (Node B) and to estimate the downlink capacity improvement by implementing this novel algorithm. Simulation was done based on a single micro cell environment with consideration of interference from the first tier. User mobility is taken into account to provide a combined evaluation of Radio Resource Management (RRM). Capacity system expressed in downlink outage under various simulation scenarios was represented in this paper.