China Mobile – 4G/LTE – CSFB Backward Compatibility Challenges

China Mobile 4G LTEChina Mobile is leading the deployment of 4G LTE network in China while china Teleocm and Unicom are happy riding the 3G Data boom.

China Mobile [CM] is faced with one Big Technical Challenge when it comes to provide & maintain QoS for existing users along with 4G. CM is predominantly a TD-SCDMA Network and is using TD-LTE in 2.6 GHz for LTE Data. Without any doubt both the technologies are tested and proven in standalone mode. However, if you want to go for the Circuit Switch Fall Back like Airtel has deployed in Pune switching from 4G LTE to 3G or 2G, all the problems crop up as it requires very high precision coordination between the network and the user handset.

The difficulties increase significantly as these technologies generally have fundamentally different radio modulation techniques, with GSM/GPRS/EDGE (2G) based on TDM (Time Division Multiplexing WCDMA/CDMA2000 (3G) based on CDM (Code Division Multiplexing), TD-SCDMA (3G) based on a hybrid of TDM and CDM, and TD-LTE/FDD-LTE based on OFDM (Orthogonal Frequency Division Multiplexing). I believe this could be one of the final system challenges for China Mobile to address before TD-LTE becomes commercial ready for CM.

End User Devices for China Mobile 4G LTE Data Services
CM wil launch multi-mode, multi-band devices in the market from HTC, Huawei, LG, and ZTE by late 2013. In addition, all major brands have products in planning stage; Huawei and Samsung are currently in lab testing. As per our latest information, 31 TD-LTE devices have been procured and supported on the network so far. TD-LTE data cards, portable WiFi hotspots, dual-mode TD-LTE / TD-SCDMA handsets, and CPE modules; we note that these devices address a wide range of use cases for the market including both mobile service and fixed-wireless service.


China Mobile is expected to take early lead in 4G services in China with its launch of TD-LTE services in late-2013. While technologically, China Unicom and China Telecom can also migrate to 4G networks, complications around technology paths (FDD-LTE vs. TD-LTE) and spectrum availability could delay their respective 4G launch.