ry configuration to access services and management of the software on mobile devices. OMA DM supports provision, configuration, software upgrades, fault managements, and SO on, functions. OMA DM uses XML for data exchange, more specifically the subset defined by SyncML. The Device Management takes a client and server approach to handle bi directional communications. Unlike the proprietary solutions, OMA DM provides a continuous management relationship between the client (mobile terminal) and the server by using IP (XML/WBXML/HTTP)7 as bearer and by following a "feedback process approach" rather "push and forget" policy. Mobile Performance Enhancement Techniques This section briefly discusses some key techniques that can enhance the performance of handsets namely Mobile Receive Diversity (MRD), Mobile Transmit Diversity (MTD), MIMO, Interference Cancellation and Security. 10.9.1 Mobile Receive Diversity (MRD) The idea behind the Mobile Receive Diversity approach is to combine signals from two separate antennas in the handset to reduce the impact of spatial variations in signal strength and thus increase the average data rate and voice capacity. In addition to two antennas, Receive Diversity uses two receive RF (Radio Frequency) chains to improve signal reception in a mobile phone (Figure 10.11). One antenna provides both transmit and receive functions while the second antenna can ONLY receive signals. The distance XML: Extensible Markup Language. WBXML: WAP Binary XML. WAP: Wireless Application Protocol. HTTP: Hypertext Transfer Protocol. Smart Wireless Devices Mobile Chipset Figure 10.11 Mobile terminal with diversity. Reproduced with permission from Asif © 2004 IEEE [29] between the antennas could be as little as one inch [29]. The MRD can double the number of voice users and the data capacity (i.e., 3 dB gain), but the addition of elements like second antenna and RF components in the devices will be costly. The MRD based solutions will be expensive to deploy beyond high-end devices and data cards. 10.9.2 Mobile