|
 Customer
China SATCOM Guomai Communications Co., Ltd. (Guomai) provides mobile digital wireless communication services in the Shanghai province. Its network uses Integrated Digital Enhanced Network (iDEN) technology developed by Motorola to provide clear high quality voice communications, while ensuring privacy and security.
The Objective And Challenge
Guomai was in need of a solution in Shanghai that could backhaul E1 traffic from Xu Jing to Feng Xi, a distance of 7.8km. Leased line connectivity was not only cost-prohibitive, but required a lead time for installation that was unacceptable to Guomai Shanghai and its customer. Broadband wireless solutions were a consideration, but tall buildings prevented a clear line-of-sight path, and products tested could not provide a reliable connection in the Non-Line-of-sight environment. In addition, the adjacent Hong Qiao Shanghai Airport presented another challenge-high levels of RF interference that adversely affected data rates.
Technical Requirements
- In excess of 10 Mbps throughput to carry multiple E1 connections
- Intuitive installation and management features for quick deployment
- Carrier-grade reliability
- Ability to operate in NLoS environments
- Interference mitigation feature
- Security
Deployment Details
In a matter of hours, ROOTS Communications personnel together with Guomai field staff had installed the Motorola PTP 400 series radio with integrated antenna and traffic was passing between the two end points. The Xu Jing site radio was installed on a six foot mast atop a 7-storey building and connected to the Feng Xi site radio which was installed on a tower mast atop a 4-storey factory, and was connected directly to Guomai's network. The 7.8km wireless link path was obstructed by buildings.
Excessive interference combined with NLoS made this deployment particularly challenging. With the Shanghai Hong Qiao Airport in the vicinity from the installation, there were heavy periods of interference. Extreme challenges require Extreme Technology. Motorola is the only provider to combine all these proven Non-Line-of-Sight wireless technologies in a single solution:
- Multi-beam Space Time Coding
- Best-In-Class Radio (Receiver sensitivity - 96dBm)
- OFDM (Orthogonal frequency Division Modulation) - 1024 sub-carries
- Automatic frequency Selection - iDFS
- Adaptive Modulation (BPSK to QAM)
To radically increase the chances of a successful connection, Motorola's PTP 400 series radio transmits multiple de-correlated images on the date using multiple transmitters, antennas and receivers. It then recombines the signals at the receiver using advanced algorithms. To prevent the signals from interfering with each other, it utilises OFDM plus automatic frequency selection to choose whichever transmit frequency has the latest interference. Lastly, the adapted modulation rate and method are chosen automatically based on prevailing wireless conditions.
The Results
Since installation in September 2004, the 7.8km link has been running error-free with no interference supporting 2 x E1 links, even adjacent to the airport. The customer estimates the ROI to be 10 months and has since installed additional Motorola's PTP platforms on its network to backhaul E1 traffic.
“ Because our customers demand highly available connections,we were very pleased
to finally find a broadband wireless platform
that
can provide reliable
performance in
high
interference and
highly obstructed
areas, we plan to roll out this plaform in other ciites as well ”
Guo Gang, General Manager, Guomai Shanghai
|
