Strategy of AXGP in the interview
"Aim to realize large capacity mobility in urban areas"

Mr. Yoshioki Chika (VP of XGP Forum) appeared "Strategy of AXGP". -- In the interview with Business Network. (May 28, 2012)


AXGP developed by WCP is a kind of system that not only enjoys the a number of benefits of TD-LTE, but also realizes the large capacity with microcell technology of PHS. Mr. Chika, the CTO of WCP, said that AXGP will prove its real worth in combination with 3G/LTE covering a wide area.


Q: Softbank's high-speed data communication service using the network of AXGP (Advanced eXtended Global Platform) built by WCP(Wireless City Planning) has already been launched on February 24. How is the feedback?

A: We are so glad that it started out without causing our customers any inconvenience. It seems that the users are steadily increasing.


Q: You had been working on XGP at WILLCOM, which is also called 「next generation PHS」. Now you are working as the CTO of WCP which has took over XGP and pushing ahead AXGP. As I know AXGP is a system that is 100% compatible with TD-LTE which is being commercialized in China. What is the relationship between XGP and AXGP?

A: Since ten years before, we have forecasted that the capacity of network will not be sufficient by far in the mobile broadband era. Therefore we assumed that microcell network of PHS will be the optimal network for broadband and set out to develop the XGP which can utilize it very properly. However, due to changes in market environment it has become clear that the communication system cannot be maintained unless ecosystem is big enough. Thus we decided to match global ecosystem, and also keep the design concept and algorithms of XGP in the meanwhile. Accordingly, In order to strengthen the compatibility with TD-LTE, we modified the specification and that is AXGP.


Q: You said that AXGP is 100% compatible with TD-LTE. Then can we use the Chinese terminals in Japan without any process?

A: Basically, the terminal is going to work with full compatibility. Actually we are crafting on network and if we demand particulars on terminal, it cannot become ecosystem.


Q: China allocated 2.5GHz band for TD-LTE, but the frequency of WCP is different. Some says that global terminal models oriented for China’s TD-LTE cannot be used in Japan for this reason.

A: Actually the frequency band of our company is used for FDD-LTE in Europe. However, the specification of TD-LTE and FDD-LTE is almost the same, so we think at least the chipset with TD-LTE can be supported in our band. The problem is whether the manufacturers want to implement this specification to the terminal or not. There is also possibilities that they do not want to correspond for the reasons like time-consuming and so on. Therefore, we have been actively persuading handset manufactures. It is also important to create a consensus of using common TD-LTE terminal regard less of nations making use of promotion organizations including the GTI (Global TDLTE Initiative).


Q: The network of WCP is not limited to data communication, but also can be used for Smartphone, is it right?

A: Absolutely! CS fallback is a function that allows voice communication by switching to 3G when the terminal is in the area of ​​the AXGP and it will be supported soon. We are expecting to correspond whenever the manufactures issue the terminals.


Q: What is the difference between AXGP and 100% compatible TD-LTE? If terminals can be shared, what are the differences between AXGP and TD-LTE?

A: The major difference is that high density base stationing of PHS can also apply to AXGP and it makes it possible to achieve large capacity. Microcell is an effective means for expanding network capacity, yet there is one problem. That is if the cell stations are arranged too close, interference will occurs. To avoid this kind problem, a special algorithm and know-how of arranging base stations are being incorporated.


Q: Could you explain the technology specifically?

A: Technical elements are not significantly different from those used in heterogeneous networks, which has become the worldwide sensation recently. The most different point is the accumulation of know-how. We have been deploying PHS for 20 years and we know exactly how to expand capacity; we know what is necessary to avoid problems in advance. Another big difference is that WCP is able to realize high capacity network with microcell promptly by using 150,000 PHS base stations. Of course we have also altered our attitude to technology development.


Q: XGP Planned to realize microcell by sharing antenna with PHS. What about AXGP?

A: AXGP also shares antenna with PHS. It is not easy to discriminate, yet AXGP common base station has exchanged 8 element type antennas with thicker ones. Because high function filters are installed in those, the wave of AXGP and PHS can be departed explicitly. PHS and 3G have been already sharing antennas. Common Antennas applicable for PHS, 3G, AXGP simultaneously will be come out to the surface soon. 「Common」 is the key in making cheap infrastructure.


Q: Do you mean you are planning to install AXGP base stations in the urban areas in the same density of PHS?

A: This is the lowest goal and must be carried out because it is just the chance for us. The combination of AXGP and 3G is the best.


Q: The current business of WCP is just selling network line to SoftBank. UQ Communications, the operator of WiMAX, are selling network in large scale to MVNO like electrical appliance stores. Do you have the same idea?

A: We are also reviewing that kind of strategy. On the other hand we believe that it is essential to provide large capacity with low cost, yet to achieve this goal it is better not to expand areas in large scale. Let AXGP cover high traffic areas, and let others cover 3G/LTE, then cost will go down fairly. Presently, it is best to deploy to the 3G network users as wholesale in this way. It does not make sense that to extend to 99% population coverage area with high frequency of 2.5GHz.We need to utilize Spectrum wisely considering its characteristics. We are planning to build out an area about 92% in this year and then would rather add thickness than extend to more area. We believe this is our responsibility.