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Radio convergence complicates device development
Mobile broadband devices incorporate multiple radio and frequency band support for incremental services and coverage everywhere.
A multi-mode mobile communications device is one that supports multiple radios and protocols. Unlike cellular phones that only support GSM, UMTS, or CDMA today, a multi-mode device supports multiple, non-compatible protocols. A combination of GSM, CDMA, WiMAX, LTE, Wi-Fi, GPS, Bluetooth, and Near-Field Communications are examples of radios that could be combined in a multi-mode device.
The benefits of a multi-mode device include signal coverage in more places and support for more applications and services. Cellular voice networks do not have the capacity to support high-speed Internet access. A multi-mode device could utilize the cellular radio for voice services, while utilizing a dedicated data radio for Internet-based services.
Each radio supports one or more frequency bands. A GSM phone that has quad-band support means that it can be used on GSM cellular networks that support any of four frequency bands. Different protocols and frequency bands also have different antenna requirements. Is it easy to see how complicated the device becomes when multiple wireless protocols, radios and frequency bands are incorporated.
Several chipset announcements underscore the trend towards multi-mode capability. Intel is expected to begin shipments of its Wi-Fi/WiMAX combination chipset, called Montevina, this year for embedded notebook systems. Comsys has developed a pair of reference designs that converge Bluetooth, Wi-Fi, GPS, WiMAX, and GSM/EDGE. Qualcomm announced LTE chipsets that pair: UMTS, HSPA+ and LTE; EV-DO Rev. B, UMB and LTE; or UMTS, HSPA+, EV-DO Rev. B, UMB and LTE. NXP chose to address end-users' demands to be continuously connected in the best possible way on a single mobile phone breaking-down the RF portion of the design into three classes, based on data rates. For example, the low-end would include a combination RF chip dealing with Near-Field Communication, Bluetooth, Zigbee, Wibree and UWB; in the middle-tier is a reconfigurable RF channel for cellular communications; and for high data rates a reconfigurable RF channel for high-bandwidth applications such as Wi-Fi, WiMAX and LTE is proposed.
Samsung Electronics has already introduced a couple multi-mode WiMAX devices for consumers. The company's SPH-M8200 PDA-type device supports Mobile WiMAX and CDMA EV-DO connectivity. It also supports Mobile TV (using the Terrestrial DMB protocol) and Bluetooth. Samsung is also developing a tri-radio PC Card for SKTelecom in Korea that supports WiBro (Mobile WiMAX), CDMA 1x EV-DO and HSDPA.
By Jeff Orr
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