OVER TIME, WIMAX is expected to achieve similar attach rates to devices as WiFi. Yet it will not eclipse the usefulness of WiFi. In fact, service providers can bundle WiMAX and WiFi to deliver high-speed Internet connectivity in more places. In a joint paper from Intel and Motorola, the companies focus on the synergies between the IEEE 802.11a/g/n Orthogonal Frequency Division Multiplexing (OFDM) and IEEE 802.16e-2005 OFDM-Access (OFDMA) air interfaces.

The 10-page paper, which is titled "WiMAX and WiFi Together: Deployment Models and User Scenarios," notes that both technologies leverage OFDM and advanced antenna innovations to attain high-broadband data rates and improved signal reception. Yet they have clearly been optimized for different usage models. The paper details those models and their associated characteristics in addition to the strengths and uses that could be created by bundling them together. With scalable OFDMA, WiMAX operators can build on fixed services by adding broadband connectivity on the move. Such capabilities can enable hot-spot providers to extend the range of their services.

The note delves into each of the following usage scenarios and explains how they can be better served by a combination of WiMAX and WiFi: last-mile broadband, broadband campus coverage, and citywide broadband. In citywide networks, for example, WiMAX can be used to wirelessly backhaul the WiFi mesh portals to the Internet. In addition, that WiMAX network can provide an overlay solution that enables the service provider to offer a two-tier service to subscribers. With such an offering, users can connect according to their mobility, bandwidth, and quality-of-service (QoS) requirements. If they are in close proximity to a WiFi access point, for example, users can connect via WiFi for high-bandwidth streaming. When they are in an area that is not covered by the mesh network or they need higher QoS for a video session, they can connect via WiMAX.

These possibilities are based upon the potential of IEEE 802.16e-2005 mobile WiMAX and IEEE 802.11n WiFi. The WiFi industry is currently transitioning to IEEE 802.11n, which is based on multiple-input multiple-output (MIMO) antenna advancements. Because both technologies are based on an OFDM air interface, they can share silicon blocks at the baseband level. The technologies also share MIMO-antenna mechanisms, making it possible for them to share the same antennas. This paper closes with an overview of the progress made by the WiMAX Forum's Network Working Group (NWG), which has developed specifications for users transitioning between WiMAX and different access technologies like WiFi. The interworking between WiMAX and WiFi is simplified because both networks are deployed using Internet Engineering Task Force (IETF) protocols.

Motorola, Inc., 1303 East Algonquin Rd., Schaumburg, IL 60196; (847) 576-5000, Internet: www.motorola.com.

Intel Corp., 2200 Mission College Blvd., Santa Clara, CA 95054-1549; (408) 765-8080, Internet: www.intel.com.