Ericsson and Qualcomm, Inc. Demonstrate World's First Release 9 Circuit Switched Fallback from LTE TDD to GSM

In order to facilitate the reuse of existing GSM networks, Ericsson and Qualcomm Incorporated have demonstrated the world’s first Release 9 Circuit Switched Fall Back (CSFB) from LTE TDD (TD-LTE) to GSM, live, using a standard Ericsson radio base station RBS 6000 and an LTE multimode chipset from Qualcomm.

With this achievement, both LTE FDD and LTE TDD modes, using un-paired spectrum, could also make use of the broad GSM coverage.

A live, public demonstration at the PT Expo in Beijing was held with Ericsson LTE TDD network and Qualcomm chipset. It supports the development of LTE multi-mode devices, providing a better user experience through the implementation of Release 9 CSFB in the network and device.

With circuit-switched fallback (CSFB), when the user’s device is operating in LTE (data connection) mode and a call comes in, the LTE network pages the device. The device responds with a special service request message to the network, and the network signals the device to move (fall back) to 2G/3G to accept the incoming call.

For outgoing calls, the same special service request is used to move the device to 2G/3G to place the outgoing call.

The mobile communication standard Long-Term Evolution (LTE) is optimized for data transfer and designed as a packet switched all-IP system only; it does not include any circuit switched domain currently used for regular voice and SMS services. Demand for mobile broadband services is proven in the increase of data traffic. Recently, operators have been launching high-speed data networks with LTE technology. However, voice and SMS business still generates around 70 percent of total operator revenue globally, and it has become clear that voice functionality needs to be provided on LTE networks.

Rajani Baburajan, a MobilityTechzone Contributor, reported that running VoLTE is also more spectral efficient compared to running voice over 2G or 3G, which provides an opportunity for better radio resources utilization when deploying mobile broadband. It will provide operators with a comprehensive set of globally standardized, telecom grade quality services to combine with high-speed mobile broadband services.

Customers will benefit from telecom-grade HD voice, video calling and other new and richer communication services on LTE smartphones. 

The new-generation mobile communication standard LTE is expanding rapidly as data traffic over mobile networks grows 15 times every year. Ericsson (NASDAQ: ERIC) estimates that smartphone subscriptions will reach around three billion in 2017.

While data traffic is increasing and IP-based packet networks like LTE are adopted globally, coverage for voice and SMS is still larger in legacy circuit-switched networks such as GSM. Already today, 85 percent of people on Earth have access to GSM mobile communication networks and Ericsson estimates that 90 percent of the world’s population will be covered by 2017.

Serge Willenegger, Qualcomm’s vice-president of Product Management, says they were pleased to be part of this important industry milestone, having worked very closely with Ericsson. He added that the efficient support of voice and messaging services in LTE multimode smartphone platforms is instrumental in driving device economies of scale in key LTE TDD regions such as China.

Willenegger went on to add that CSFB utilizes the same power-efficient, single radio chipset architecture from Qualcomm that has been widely proven for LTE FDD CSFB support.

Per Narvinger, Ericsson’s head of Product Line LTE, Business Unit Networks, says that for carriers and service providers, available frequency bands for communication services are limited and are precious resources. He also said that multi-mode networks and devices that make the best use of these resources are crucial for providers to be able to stay competitive and serve consumers in the best way.

LTE TDD, which uses an unpaired spectrum, is one of the important technologies to support the rapid uptake of smartphones and data traffic growth in operator networks.

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