Telefónica is one of the largest telecom operators and mobile network providers in the world, with more than 346 million subscribers in 21 countries. It operates the Movistar mobile phone brand throughout Latin America. ZTE and Telefónica have established strategic partnership in several technological areas of interest to the company, including radio technologies.
ZTE has established relationship with Movistar Venezuela in microwave (MW) transmission since 2013. A contract of 1000 hops of MW was signed by both parties. Considering the highly focus on hybrid access of multiple service and smooth LTE-oriented evolution, ZTE provided NR8000 series microwave products—ZXMW NR8250/NR8120 based on hybrid and packet platform, which would enable smooth evolution from 2G/3G to LTE backhaul. In this project, there is a super long distance MW link up to 92.23 kilometers from Guasdalito to Cerro Azul. It is a big challenge for microwave due to performance decrease by multipath fading and specular reflection. Besides, this is a key link on backbone transmission, where a fair amount of sites would be affected in case of any failure. Hence, high reliability and outstanding transmission performance with high throughput are the most important for this link. ZTE proposed space diversity (SD) technology with 3.7 meters diameter antennas to guarantee transmission reliability. Cross polarization interference canceller (XPIC) technology was also used to achieve high throughput transmission. Finally, the outstanding performance and high reliability of ZXMWNR8000 series products impressed Movistar, which lay a good foundation for the subsequent long and stable cooperation between ZTE and Movistar.
In 2015, Telefónica Group launched a new Global MW RFP for 2016 deployment. ZTE’s new-generation MW products started homologation tests with Telefónica Group in the branches of Ecuador (field trial), Panama (field trial), Venezuela (lab tests only) and Nicaragua (field trial). Based upon the results of these tests, ZTE would be able to participate in the Global MW RFQ bidding process.
In Nicaragua, another long distance MW link of the existing network was facing challenges such as antenna size—the diameter should not be larger than 2 meters, installation space—no indoor space, over lake and long distance (88 kilometers)—severe specular reflection. ZTE proposed NR8000 TR 4+4 XPIC SD with physical layer aggregation (PLA) solution to meet the challenges. The transmitting power of NR8000 increased 2 dB, which lowered the requirement for antenna size. Only 1.8 meters antennas were used to fulfill the requirement. NR8000 could also be installed in an outdoor cabinet—zero footprint. Moreover, PLA with XPIC functionality solved the conflict between throughput and distance, and SD configuration addressed the issue of specular reflection.
[Keywords] Telefónica, microwave transmission, space diversity, XPIC, MW link, Telefónica Movistar