Carrier Aggregation (CA) is one of the key features in Long Term Evolution-Advanced (LTE-A) to support wider bandwidth than the bandwidth supported by LTE. In this chapter, design and implementation of LTE-A to support greater bandwidth by improving the carrier aggregation technique and deployment scenarios such as intra-band contiguous carrier aggregation, intra-band non-contiguous carrier aggregation, and inter-band non-contiguous carrier aggregation are provided. As a result, this chapter presents the first evolution case of carrier aggregation on LTE-Advanced to support bandwidth up to 120 MHz in contiguous carrier aggregation instead of 100 MHz and 100 MHz in non-contiguous carrier aggregation instead of 80 MHz, where these challenges can provide high peak data rate, low latency, and high spectral efficiency. Although LTE already in its first release provides very high performance, it can also serve as a robust structure for evolving into even higher performance, as prospectively the revolution will go on beyond LTE-A to converge future requirements emerging with increased user expectations.
TopIntroduction
The developments of carrier aggregation in Release 10 (LTE-A) specifications are continuing to provide enhanced capacity and higher peak data rates. Some extensions are provided in Release 10, including support for User Equipment (UE) positioning and enhanced beamforming (Song & Shen, 2011). The initial version of Release 8- LTE can satisfy many of these demands in terms of the peak data rate requirements, spectral efficiency and some particular deployment scenarios which require significant new features and provide extensive support for deployment in spectrum allocations of various characteristics, with transmission bandwidths ranging from 1.4 MHz up to 20 MHz in both paired and unpaired bands. While release 10 (LTE-Advanced) transmission bandwidth can be further extended with carrier aggregation (CA), where multiple component carriers are aggregated and used for transmission to/from a single mobile terminal. Carrier aggregation has two scenarios: intra-band carrier aggregation and inter-band carrier aggregation, as described in section 8, both of which can achieve higher bandwidth and throughput.
LTE standard evolution from Rel-8 to beyond Rel-11 is shown in Figure 1. Importantly, the one eminent challenge of Release 11 is carrier aggregation, whereby multiple carriers at several frequencies, and possibly of several bandwidths, are used in coupling with each other in a single cell, as explained schematically in Figure 1 (Zhang & Zhou, 2013).
Figure 1. LTE evolution from Rel-8 to Rel-11
In addition, this chapter also describes the two main parts of LTE-Advanced. The first part concerns the uplink (UL) and presents Single Carrier Frequency Division Multiple Access (SC-FDMA), where the data from mobiles is transmitted from user equipment (UE) to the base station (eNB). The second part covers the downlink (DL) and which presents Orthogonal Frequency Division Multiple Access (OFDMA), where data from mobiles is transmitted from the base station (eNB) to user equipment (UE).
This chapter presents LTE-A downlink designed to increase the number of component carriers which lead to reach bandwidth equal to 120 MHz in contiguous carrier aggregation, instead of 100 MHz and 100 MHz in non-contiguous carrier aggregation while it was 80 MHz only. All the fundamentals of MIMO are included in section II, while its capacity is explained in section III. Section IV then goes on to cover the combination of MIMO with LTE-Advanced, which is followed by sections V and VI that present LTE-Advanced as peak data rate and peak spectral efficiency, respectively. The design of the downlink for LTE-Advanced is then explained in section VII, while all the scenarios of carrier aggregation are described in section VIII. Following this, all the types of intra band carrier aggregation (contiguous and non-contiguous) are included in sections IX and X. Simulation examples of these cases with all the results are included in sections XI and XIII. Finally, the main conclusions from the implementation of the proposed new design are explained in conclusion section.
TopThe use of the term MIMO is meant to differentiate it from a classical wireless system where a single antenna is used both at the transmitting and at the receiving end, called Single Input Single Output (SISO). More generally, it is common to define an antenna system related to the number of antennas at the receiver and transmitter. Figure 2 shows four antenna configurations that can characterize any wireless radio communication system: SISO, Single Input Multiple Output (SIMO) (which is characterized by a single transmit antenna and multiple receive antennas), Multiple-Input Single-Output (MISO) (which is characterized by multiple transmit antennas and a single receive antenna), and MIMO, where multiple antennas are used at both ends of the transmission. Multi antenna techniques are used in order to achieve the following parameters:
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Diversity gain;
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Array gain;
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Multiplexing gain.