Performance analysis of LTE-advanced networks in different spectrum bands

Hutchison 3G under the brand name of Three launched 3rd Generation Partnership Project, 3GPP Rel 5 High Speed Downlink Packet Access (HSDPA) networks, worldwide. The HSDPA network is capable of delivering data rates up to 21 Mbps today. In Rel 7, 3GPP standardised HSPA Evolution (HSPA+) which was specified to deliver maximum user data rates up to 42 Mbps by using dual Carrier Aggregation and 64 QAM in the Downlink. Since the launch of HSDPA network in the UK, Hutchison 3G observed significant increase in the data traffic. In order to deliver Mobile BroadBand (MBB) services to its customers more efficiently, Three UK has started to focus on new technologies which have been standardised by 3GPP in Rel 8/9/10. Although Long Term Evolution (LTE) network performance was studied by other researchers, the aim of this paper is to analyse the performance of LTE Carrier Aggregation (CA) in different spectrum bands to meet the International Mobile Telecommunications Advanced (IMT-Advanced) requirements.

I. Introduction

Convergence of mobile and internet puts pressure on mobile service providers to offer faster and more efficient mobile internet access. Today, High Speed Packet Access (HSPA) networks are delivering high volumes of data transactions. However, the growth in video downloads and the increase in data usage due to smart phones will require larger air interface bandwidths. Long Term Evolution or LTE, on the other hand, is the evolution of HSPA, which was first standardized in 3GPP Release 8 to support larger bandwidths [1]. One of the requirements of LTE was to provide higher averaged user throughput. It was specified to deliver services with high efficiency based on Internet Protocol (IP). Unlike HSPA, LTE adopts Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink and Single Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink direction for resource sharing among multiple users. These multiple accesses increase network capacity and user throughput because of multi-user diversity gain. One of LTE features is that the operators can select various spectrum bandwidths, e.g., 1.4, 3, 5 10, 15, and 20 MHz depending on availability. 3GPP has further extended the original proposal of LTE, which is known as LTE-Advanced [2]. LTE-Advanced can be considered as one of the prominent 4G proposals that has been specified by 3GPP in Release 10. LTE-Advanced should, however, provide a backward compatibility in terms of spectrum coexistence with Release 8 based LTE. This means that it should be possible to implement LTE-Advanced in a spectrum which is already occupied by LTE devices. Furthermore, LTE-Advanced will also use the same radio interface technology as LTE.