Achievement Award

Commercial Deployment of Advanced C-RAN for LTE-Advanced Akihiro MAEBARA，Sadayuki ABETA，Norihito TOKUHIRO

Akihiro MAEBARA Sadayuki ABETA Norihito TOKUHIRO

Since 2008, the widespread adoption of smartphones is driving continued growth of new mobile applications such as social networking and video streaming, causing mobile data traffic to increase 1.5-fold every year. Such rapid traffic growth is posing a challenge to mobile operators around the world. The LTE system, which was launched around 2010, provides faster data speeds and higher capacity than the 3G system, and can effectively handle the rapidly growing traffic. However, in order to meet the ever-increasing traffic demand in the years to come, it is also necessary to add new frequency bands and make good use of cells with a smaller radius (small cells) to further increase radio capacity per unit area in the mobile network.   The award winners found a solution to the challenge mentioned above. They devised a new concept of radio network architecture called Advanced C-RAN (Centralized Radio Access Network) as a means to efficiently configure a radio network. While using standardized technologies of LTE-Advanced, an enhancement of LTE, the new Advanced C-RAN architecture takes advantage of the features of C-RAN, the centralized architecture of which enables cost reduction and tight coordination among cells. As shown in Figure 1, the Advanced C-RAN architecture accommodates a heterogeneous network where macro cells and small cells coexist. In this architecture, by applying the carrier aggregation (CA) technology of LTE Advanced, different frequency bands allocated to the small cells and macro cells can be used simultaneously. This enables the deployment of small cells which can flexibly and efficiently add capacity to handle congestion in high traffic areas while ensuring stable communication quality for moving user terminals through tight coordination between macro and small cells. Thus, the new architecture provides mobile operators with the capability to deploy high-speed, high-capacity and high-quality communications with less effort and more efficiency.   The award winners have made a remarkable contribution by leading the standardization work in 3GPP, a standardization body for LTE-Advanced, by contributing numerous technical proposals and working on the development of standard specifications for CA. In addition, they have given lectures at both domestic and international academic meetings and published papers on CA performance evaluation between macro cells and small cells, indicating the direction research should take and identifying new issues. Furthermore, by making the basic ideas of CA technology open and available, they have made a crucial contribution to the development of mobile communications technology as a whole. Figure 1 Advanced C-RAN Architecture   The award winners’have also made a contribution to the commercialization of CA technology, enabling the launch of a high-speed LTE-Advanced service (March 2015) with a maximum data rate of 225Mbps (262.5Mbps in some areas), the highest in Japan. The LTE-Advanced service has been deployed in 640 major cities nationwide through 7700 base stations in about 6 months since its introduction (as of the end of September). The number of user terminals supporting LTE-Advanced has already exceeded one million and is still rapidly growing, raising expectations for a new market that will stimulate the use of rich content through the mobile network.   Advanced C-RAN is a highly valuable form of architecture and will undoubtedly serve as the basis for further development of mobile communications systems toward 5G in the years to come. Achieving the world’s first commercial use of Advanced C-RAN is a remarkable contribution that will benefit the entire mobile communications community.   Consequently, the contribution of the award winners is extremely important and highly deserving of IEICE’s Achievement Award.

References

（1）Abeta, Atarashi, “Radio Access Network for Ultra High Speed Broadband Services,”　The IEICE General Conference, March 2012. （2）Atarashi, Abeta, “Activities on development of LTE-Advanced”　The IEICE Society Conference, September 2013. （3）T. Takiguchi, K. Kiyoshima, Y. Sagae, K. Yagyu, H. Atarashi, and S. Abeta, “Performance Evaluation of LTE-Advanced Heterogeneous Network Deployment Using Carrier Aggregation between Macro and Small Cells,” IEICE Tans. Commun., vol. E96-B, no.6, June 2013. （4） Abeta, Kawahara, Futakata, “LTE- Advanced as Further Evolution of LTE for Smart Life,”　NTT DOCOMO Technical Journal, Vol.23 No.2. Jul.2015, pp 6-10. （5）Kiyoshima, Takiguchi, Kawabe, Sasaki, “Commercial Development of LTE- Advanced Applying Advanced C-RAN Architecture -Expanded Capacity by Add-on Cells and Stable Communications by Advanced Inter-Cell Coordination” NTT DOCOMO Technical Journal, Vol.23 No.2　Jul.2015, pp11-18. （6）Yoshihara, Toeda, Fujii, Suwa, Yamada, “Radio Equipment and Antennas for Advanced C-RAN Architecture” NTT DOCOMO Technical Journal, Vol.23 No.2　Jul.2015, pp19-24.