by a multipath improves the rank distribution of the channel matrices across frequency tones, thereby increasing the capacity. Planning Overview for 4G Networks Increasing demand for a high performance 4G broadband wireless mobile calls for the use of multiple antennas at both the base station and subscriber ends. These multiple antennas technologies provide high capacities suited for multimedia services and also increase the range and reliability. Multiple antennas at the transmitter and receiver also provide diversity in a fading environment. MC-CDMA MC-CDMA is actually an OFDM with a CDMA overlay. Here the users are multiplexed with orthogonal codes to distinguish users in MC-CDMA. In MC-CDMA each user can be allocated several codes where the data are spread in time or frequency. Local Multipoint Distribution System (LMDS) The local multipoint distribution system (LMDS) is the broadband wireless technology used to deliver voice, Internet and video services in the 25 GHz and higher spectra. 5.4.2 Network Architectures in 4G The three possible architectures that can be used in the future are as follows. Multimode Device This configuration basically uses a single physical terminal with multiple interfaces to access different wireless networks like AMPS and the CDMA dual-function cell phone. This multimode device architec- ture is advantageous as it may improve call completion and expand the effective coverage area. It should also provide a reliable wireless in the case of network, link or switch failure, and the user, device or network can initiate a handoff between networks. The handling of quality-of-service (QoS) is the main issue in this case. Overlay Network In this case a user accesses an overlay network consisting of several universal access points (UAPs). These UAPs in turn select a wireless network based on availability, QoS specifications and user-defined choices. A UAP performs protocol and frequency translation, content adaptation and QoS negotiation- renegotiation on behalf of users. The overlay netw