LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Evolution of the IMT-Advanced Standards

Despite the many similarities between LTE and WiMAX, their origins are radically different. While LTE is the inheritor of a voice-service based technology, namely the voice circuit switching, WiMAX originated from a data-service based technology, the computer networks. In other words, WiMAX was born as an all IP technology while LTE went through a slow and long development stages to become an all IP network. The evaluation of both standards is shown in Figure 15.1.

LTE predecessors can be traced back to the circuit-switched analog, 1G networks. These networks were designed in the mid 80s to deliver voice services to mobile users. Shortly afterwards, the 2G circuit-switched networks had evolved to improve the quality of these services. This has been achieved through using digital communications techniques, including modulation and coding. In this generation, two technologies prevailed, the TDMA based GSM and the CDMA based IS-95. The development of these two technologies was led by two standardization bodies, 3GPP leading GSM and 3GPP2 leading IS-95. GSM supported voice services neatly; however, it fell behind in data services. This motivated the development of GPRS technology as a 2.5G network. This technology could successfully handle data services over the GSM circuit switched network. Since then, 3GPP continued its work in improving the performance of the data transmission capabilities by increasing the supported data rates over the GSM ...