Future Enhancements

There are likely to be many future enhancements to mobile radio. Some of the key innovations include software defined radios, spatial division multiple access (SDMA), and 4th generation mobile telephones.

Software Defined Radios

Software defined radios are transceiver devices that use digital signal processing to create and decode radio messages. Because they use digital signal processing for almost all functions, it is possible to change access technologies and radio transmission characteristics through software changes. Thus it may be possible in the future for a handset or other terminal to download the necessary parameters of a network as the mobile moves from one technology to another.

Spatial Division Multiple Access (SDMA)

Spatial Division Multiple Access (SDMA) is a technology that increases the quality and capacity of wireless communications systems. Using advanced algorithms and adaptive digital signal processing; Base Stations equipped with multiple antennas can more actively reject interference and use spectral resources more efficiently . This would allow for larger cells with less radiated energy, greater sensitivity for portable cellular phones, and greater network capacity.

Figure 1.9 shows an example of an SDMA system. Diagram (a) shows the conventional sectored method for communicating from a cell site to a mobile telephone. This system transmits a specific frequency to a defined (sectored) geographic area. Diagram (b) shows a top view of a cell site that uses SDMA technology that is communicating with multiple mobile telephones operating within the same geographic area on a single frequency. In the SDMA system, multiple directional antennas or a phased array antenna system directs independent radio beams to different directions. As the mobile telephone moves within the sector, the system either switches to an alternate beam (for a multi-beam system) or adjusts the beam to the new direction (in an adaptive system).

Figure 1.9: Spatial Division Multiple Access (SDMA)

Fourth Generation (4G) Networks

Even before 3G networks are fully launched and utilized, various study groups are considering the shape of the next generation of cellular technology, so called 4G. There is no single global vision for 4G as yet but the next generation of network is likely to be all IP-based, offer data rates up to 100 Mbps and support true global mobility. One route towards this vision is the convergence of technologies such as 3G cellular and Wireless LANs (WLANs).