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ZTE Communications ›› 2010, Vol. 8 ›› Issue (2): 43-47.

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Impacts of GPS Synchronization Loss on TD-SCDMA Network Performance

Ji Shuping, Liu Zhijian, Dong Hui   

  1. ZTE Corporation, Shenzhen, 518004, P. R. China
  • 出版日期:2010-06-25 发布日期:2020-02-27
  • 作者简介:Ji Shuping received his doctoral degree from Harbin Institute of Technology. He is a senior engineer at ZTE Corporation. His research interests include wireless technologies for TD-SCDMA system. He has published more than 30 papers, and has 3 patents.

    Liu Zhijian graduated from Dalian Institute of Light Industry. Working at ZTE Corporation, he is engaged in TD-SCDMA wireless system testing.

    Dong Hui graduated from Shanghai Polytechnic University. Working at ZTE Corporation, he is responsible for TD-SCDMA wireless system testing. He has published 5 papers, and has 5 patents.

Impacts of GPS Synchronization Loss on TD-SCDMA Network Performance

Ji Shuping, Liu Zhijian, Dong Hui   

  1. ZTE Corporation, Shenzhen, 518004, P. R. China
  • Online:2010-06-25 Published:2020-02-27
  • About author:Ji Shuping received his doctoral degree from Harbin Institute of Technology. He is a senior engineer at ZTE Corporation. His research interests include wireless technologies for TD-SCDMA system. He has published more than 30 papers, and has 3 patents.

    Liu Zhijian graduated from Dalian Institute of Light Industry. Working at ZTE Corporation, he is engaged in TD-SCDMA wireless system testing.

    Dong Hui graduated from Shanghai Polytechnic University. Working at ZTE Corporation, he is responsible for TD-SCDMA wireless system testing. He has published 5 papers, and has 5 patents.

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摘要： In Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, the Global Positioning System (GPS) signal is often blocked or experiences interference. As a result, the GPS satellite cannot be found and synchronization cannot occur. Long out-of-sync periods can lead to timing differences between base stations, and if these differences are too large, they can affect the ability of Mobile Stations (MS) to search neighboring cells. This can also affect cell switchover, and cause Downlink Pilot Time Slot (DwPTS) to interfere with Uplink Pilot Time Slot (UpPTS). All these manifest as handover failures, call dropouts during handover, and a declining rate of call completion. As a consequence, user experience within the network is diminished. Researchers have found that when GPS synchronization is lost for more than 4 chips, network quality deteriorates noticably. When the loss is more than 10 chips, the MS may fail to locate a neighboring cell. When the loss is below 16 chips, the interference of DwPTS with UpPTS is not obvious in the first and second circles of the GPS out-of-sync cells. Studies show that, to protect network performance, the TD-SCDMA system allows for up to 4 chips of timing difference in the case of GPS synchronization loss.

Abstract: In Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, the Global Positioning System (GPS) signal is often blocked or experiences interference. As a result, the GPS satellite cannot be found and synchronization cannot occur. Long out-of-sync periods can lead to timing differences between base stations, and if these differences are too large, they can affect the ability of Mobile Stations (MS) to search neighboring cells. This can also affect cell switchover, and cause Downlink Pilot Time Slot (DwPTS) to interfere with Uplink Pilot Time Slot (UpPTS). All these manifest as handover failures, call dropouts during handover, and a declining rate of call completion. As a consequence, user experience within the network is diminished. Researchers have found that when GPS synchronization is lost for more than 4 chips, network quality deteriorates noticably. When the loss is more than 10 chips, the MS may fail to locate a neighboring cell. When the loss is below 16 chips, the interference of DwPTS with UpPTS is not obvious in the first and second circles of the GPS out-of-sync cells. Studies show that, to protect network performance, the TD-SCDMA system allows for up to 4 chips of timing difference in the case of GPS synchronization loss.