During the past few decades wireless technology has seen a tremendous growth. The recent introduction of high-end mobile devices has further increased subscribers' demand for high bandwidth and quality of service. The number of nodes in future cellular systems will be too large to be configured and maintained manually. Further the mobility of users, the varying nature of the wireless channel and variation in user demand systems requires optimization of network parameters and delay in configuration may cause congestion and poor Quality of Service. Due to this increased complexity and the huge scale of wireless systems the network configuration, optimization and maintenance process performed by radio engineers has become inefficient and therefore, lot of research is being done to introduce self-optimizing capabilities within the network, which is expected to permit higher end user Quality of Service (QoS) and less operation cost and maintenance cost for telecom service providers. This chapter details the key aspects related to self optimization of next generation cellular networks.
Top1. Introduction
Wireless technology has seen a tremendous growth during the past few decades. Mobile & wireless applications have become an important part of our daily lives; as a consequence user demand for data consuming mobile applications like interactive TV, mobile video, advanced games and so on has increased. It is becoming increasingly difficult to accommodate the demand of high bandwidth and quality of service.
In today's mobile networks many network elements and associated parameters are manually configured, due to exponential increase in number of users this manual process is error-prone and time consuming resulting in long delays which reduces Quality of Service. In addition training and maintaining skilled manpower is costly. Therefore, researchers are seeking to introduce self-organizing capabilities within the network, which is expected to permit higher end user Quality of Service (QoS) along with more spectrums to meet the rising mobile data demands from Subscribers. This chapter details key aspect related to self optimization of next generation cellular networks namely
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Automatic Neighbour Relations
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Load Balancing Optimization
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Handover optimization
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Random Access Channel Optimization
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Inter-Cell Interference Coordination
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Coverage and Capacity Optimization
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Energy Saving
It is expected that the development of novel self-optimization or self-healing methods will make the planning and management of future generation wireless networks much easier and minimize the needed human involvement. The next section gives a brief background of architecture of modern wireless networks subsequent sections outline the concept of self organization in next generation cellular networks.
Top2. Background
4G is Fourth generation of mobile/wireless broadband services which provides mobile ultra-broadband Internet access. 4G is a collection of wireless standards, and can be realized using various technologies; one of them is Long Term Evolution(LTE).
LTE/LTE-A (Long Term Evolution Advanced) based wireless broadband technology is basically designed to support mobile Internet access. The main features of LTE are:
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IP based system,
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High peak data rate,
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Flexibility of spectrum usage,
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Low latency times,
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Efficient radio usage,
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Higher capacity per cell,
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Cost-efficient deployment, etc.
4G supports IP (Internet Protocol) based packet switching communication system with OFDM (Orthogonal Frequency Division Multiplexing) multi-carrier transmission and other frequency domain schemes. This helps to obtain high data transfer rates, which are further increased by using Antenna arrays for MIMO (Multiple Input Multiple Output) communication to avoid multi-path propagation losses. The radio interface of LTE is based on Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink and Single Carrier-Frequency Division Multiple Access (SC-FDMA) in the uplink to provide high data bandwidth along with high-degree resilience to reflections and interference. SC-FDMA has the advantage of smaller peak to average power ratio and more constant power to get high RF power amplifier efficiency in the mobile handsets. Downlink peak rates are at least 100 Mbps while Uplink rates are at least 50 Mbps with RAN round-trip times of less than 10 ms.
Downlink and Uplink frames are shown in Table 1.
Table 1. Downlink and Uplink frames
| Downlink Frame (OFDMA) |
| Preamble | Header | Burst-1 | Burst-2 | Brust-3 | ------------- |
| Uplink Frame (SC-FDMA) |
| Preamble | Burst-1 | Preamble | Brust-2 | Preamble | Brust-3 | ---------- |