Dynamic Coordination for High-Speed and Seamless User Experience
Static coordination clusters are required for standard CoMP technologies, and the coordination cluster size is limited. Although fairly good coordination performance can be achieved inside a coordination cluster, user experience decreases sharply when users go across the borders of coordination clusters.
Cloud Radio solution uses dynamic coordination scheme, which implements seamless coordination in both macro-macro scenario and macro-micro scenario. This solution provides high-speed wireless access and the best static and mobile user experience.
Innovative Applications of Cloud Radio
Cloud Radio solution is applicable to both popular distributed base station construction scenario and the C-RAN deployment scenario (centralized baseband pool). The main highlight of this solution is rapid deployment based on the existing mobile bearer networks.
Here are the field test results of Cloud Radio solution in commercial LTE networks.
Tianhe Business District of Guangzhou: the First Show of Cloud Coordination
During the Cloud Radio test in the Tianhe Business District of Guangzhou, ZTE easily achieved the network-level inter-site cloud coordination function without making any modifications in third-party PTN transmission networks, which is the first in the industry. Take joint reception for example, the bearer bandwidth required by standard LTE-A solutions is several Gbps, and the delay must be less than several hundred microseconds.
ZTE's innovative Cloud Radio technology requires a bandwidth of only several hundred or tens of Mbps, and the delay can vary from several hundred microseconds to several milliseconds. Therefore, ZTE's solution does not need dark fiber transmission resources or bearer network upgrade/reconstruction but uses the spare bandwidth in exiting IP bearer networks to bring considerable performance profit for operators.
The test result shows that, after using ZTE's inter-site cloud coordination technologies, the probability of the throughput being lower than 2 Mbps decreased from 8% to 1%, and that of the throughput being lower than 4 Mbps decreased from 20% to 8%. The throughput of the 5% users with the lowest access rate increased by 300%, and that of the 10% users with the lowest access rate increased by 100%. This solution reduces inter-site interference and improves user performance significantly in JT, CS, and JT/CS adaptation situations.
The experts and leaders from the China Mobile Research Institute were satisfied with the test result of the Cloud Radio solution, and relevant coordination functions have been written into the technical bid specifications of China Mobile.
Huaqiao University in Quanzhou: Practice of Multi-User Test in Commercial Networks
If the field test in Guangzhou is a good start, the test in Huaqiao University in Quanzhou is really a practice of the large-scale commercial use of the Cloud Radio solution. The field test in Quanzhou involving more than 10 TD-LTE base stations and 20 users tested the uplink and downlink performance on specific spots, and verified the mobile access performance.
In the field test in Huaqiao University, the cloud coordination had extremely low requirements (for example, a maximum bandwidth of 5 Mbps and a delay of less than 4 ms) for bearer networks, and did not need reconstruction or upgrade of transmission networks. Therefore, this solution can achieve inter-site cloud coordination and make significant profit from performance improvement at the lowest network expenses.
In a scenario with 100% load of serving cell and 50% load of neighboring cell, which is similar to the commercial scenario, when CoMP is enabled, the UE throughput increased by a maximum of 237.4%, the average edge UE throughput increased by 92.7%, and the average cell throughput increased by 19.5%.
During the downlink driver test with 100% load, the throughput of 5% of the mobile users at the edge increased by 161.5% on average.
During the uplink mobile test with 100% load, the throughput of 5% of the mobile users at the edge increased by 146.7% on average, and the average cell throughput increased by 2.8%.
In addition, Cloud Radio solution is completely compatible with commercial R8 terminals, and allows users to enjoy the performance of LTE-A in the initial stage of commercial LTE use, seizing the technical advantages and market opportunities of commercial 4G use.
Dense Urban in Tianjin: Large-Scale Commercial Use of Cloud Radio Coming Soon
The field test in Tianjin involved over 30 base stations and 100 cells, and covered the most densely populated area of Tianjin, including skyscrapers, residential buildings, roads, pedestrian zones, plazas, shopping malls, and CBDs. In this area, wireless environment is very complicated, for example, the antennas are at different heights, the inter-cell interference is severe, and the cell overage is highly overlapped. In addition, Tianjin Mobile started to issue TD-LTE numbers half a year ago, and has nearly 20,000 active users, providing favorable conditions for verifying the Cloud Radio performance.
During the outdoor test, after the cloud coordination function was enabled, the throughput of edge users increased by 20% to 80%. Because indoor signals are weaker than outdoor signals, after the cloud coordination function was enabled during the indoor test, the throughput of edge users increased by 40% to 150%. In both outdoor and indoor environments, the higher the neighboring cell interference, the more obvious the coordination gains of edge UEs.
During the outdoor driving test, the CDF of mobile UE indicated that the Spectrum Efficiency lower than 1 decreased from 70–80% in a normal environment to 10–15% in a 70% load environment. Namely, after the cloud coordination and ICIC functions were enabled, the proportion of UEs with low throughput decreased by 4–5 times.
In addition, the field test in Tianjin also tested the driving performance in different network load conditions, providing valuable experience for large-scale commercial use of the Cloud Radio solution.
- Cloud Radio solution, which helps operators obtain better access performance than that of 4G networks at the lowest bearer expenses, makes ZTE occupy a favorable position in the market competition of 4G networks, and is the best choice for mobile operators in the 4G era.
- The innovative Cloud Radio solution is by far the most advanced 4G network enhancement solution, which makes ZTE rank as one of the top providers again in the industry in wireless product competitiveness.