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Modem technologies
ST-Ericsson’s platforms are inside many of the best devices on the market today and we are also carving out a leading position in the emerging mobile broadband technologies of TD-HSPA, HSPA+ and LTE (FDD/TDD).
Being a pioneer in access technologies with industry firsts such as the demonstration of a handheld LTE device utilizing a handover between HSPA and LTE and an end-to-end TD-LTE data call — we are taking the modem technology evolution into the next phase, with innovative solutions for multimode devices with global reach, bringing value to all players in the ecosystem.
Robust multimode
The latest Thor modems are all based on a new architecture concept, designed from ground up to be extraordinary flexible in terms of handling existing and future Radio Access Technologies (RATs).
While it theoretically is possible to use separate modems for 2G, 3G and 4G, it’s evidently challenging to synchronize and have the RATs co-operating seamlessly. The complexity grows exponentially with the number of RATs, since all RATs needs to be aware of the others, and that at all levels in the cellular stacks they each employ.
This is also referred to as Inter RAT - the ability to perform handovers without interruption of service. From only having to support handover of voice calls, now also services such as video and data needs to be supported. Since all sorts of services now are supported when users move across access networks, a certain Maintained level of Quality of Service (QoS) needs to be possible to guarantee. The guarantees are particularly important if the network capacity is insufficient, especially for real-time streaming multimedia applications such as voice over IP, online games and IP-TV.
Using common core structures also improves the inter-operability. Since late changes in emerging RAT standards are reality, there are no critical functions depending on hardware, instead, functions can dynamically move between hardware and software.
The new architecture provides for efficient execution and robust multimode of all 3GPP RATs.
Global roaming
Even though we are converging to a global standard with LTE, the network market is still fragmented and the allocated frequency bands depend on region and the available access technology.
The number of bands defined in 3GPP has increased tremendously and has resulted in unlimited band combinations depending on roaming agreements among operators, domestic band arrangements and operator specific bands. Furthermore needs the interference with other radio technologies, such as Bluetooth, GPS/GLONASS, NFC and Wi-Fi to be taken into account.
Since including support for all possible bands never is an option when designing a mobile device, means have to be taken to combat the band-increase without sacrificing the global roaming capability.
Thor platforms have particularly strong capabilities in ways to tailor the RF front-end solution, to facilitate band combinations that either reduce the number of bands for cost efficiency, or add bands based on specific operator demands and domestic requirements.
Also, by utilizing co-banding – using the same paths and RF front-end components for overlapping GSM and WCDMA/LTE FDD bands – the platforms cost and size can be brought down further.
The radio receiver’s strong support of multiple inputs and outputs, widely tunable to match several different frequency bands – up to eight bands, all including diversity and MIMO –results in a true global multi-band modem with unparalleled roaming capabilities.
Memory less solution
A Thor modem can operate without its own flash in Smartphone configurations.
In a standard Smartphone configuration, both the host application processor and the Thor modem have to have their own flash memory. To cut hardware costs, and to be able to further down-size the final design on PCB, it is possible to set-up the Thor modem to execute in flashless mode.
In such a solution, the modem code is loaded at boot-up from the flash memory on the Smartphone to the RAM in the Thor modem, code from which the final boot of the modem is being made.
Compact radio
The Thor M7400 RF solution is built around a 5.5 x 5.5 mm package. Thanks to the high integration, only a few components need to be added in the RF front-end to get support of up to eight bands. The radio transceiver’s particularly low noise levels mean also that no interstage filters are needed in HSPA+ and LTE bands.
This means only a very small PCB area will be occupied by the modem. The Thor M7400 reference design occupies about 500 mm2. The low component count means also savings in production costs.
