Carrier aggregation in lte-advanced

Abstract

Advancement in mobile communication technology has led to an increase in data usage due to smart electronic gadgets. Despite of increased spectrum efficiency the required data rates (1 Gbps) for 4G LTE Advanced system cannot be attained. To attain these very high data rates it is required to increase the transmission bandwidths (up to 100 MHz) over those that can be supported by a single carrier or channel. The technique being proposed is named as carrier aggregation (CA) to aggregate two or more component carriers (CCs). These channels or carriers may be contiguous components of the spectrum, or they may be in different bands resulting in Intra-band contiguous CA, Intra-band non-contiguous CA and Inter-band CA. Carrier aggregation is supported by both formats of LTE, namely the FDD and TDD variants. This guarantees that both FDD LTE and TDD LTE are capable of meeting the high data throughput requirements placed upon them. With carrier aggregation, it is likely to schedule a user equipment (UE) on multiple component carriers simultaneously i.e. multiple spectrum bands are exploited by the same user in order to fulfil the large bandwidth requirement of the service and attain enhanced performance. The first release of 3GPP LTE facilitated extensive support for deployment in spectrum allocations of several characteristics, with transmission bandwidths extending from 1.4MHz up to 20MHz in both paired and unpaired bands. One of the most significant features to drift from LTE system to LTE-A system is Carrier aggregation. Furthermore an LTE Advanced user is backward compatible with LTE. Carrier aggregation is a multi-carrier technique, where vacant SCC (Secondary Component Carrier) is combined with the PCC (Primary Component Carrier) that is allocated to the user equipment. Five component carriers each of 20 MHz are combined to increase bandwidth to 100 MHz for high data rates.