Multipath Detection Using the Dendritic Cell Algorithm

Oluropo Ogundipe, Julie Greensmith, Gethin Wyn Roberts

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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For engineering applications high precision GPS with survey grade receivers allows positioning in real-time to a centimetre level of precision. Many of the error sources affecting the GPS signal have been significantly removed in order to achieve such high precision.
However, one error source that is difficult to mitigate is that of the multipath error. GPS signal multipath occurs when the GPS signal arrives at the antenna via multiple paths. This occurs when the GPS signal is reflected off objects in the antenna environment. This is a significant problem when using GPS in an urban environment.
Carrier phase multipath error has a theoretical maximum of approximately 4cm. However, code multipath can be in the order of a few metres to tens of metres in areas of high multipath.
This can result in an erroneous carrier phase solution or no phase solution at all. The ability to mitigate this error in real-time will improve the level of accuracy and precision of GPS for surveying, engineering, and other high precision applications. In addition, with the increased use of code GNSS for personal navigation and indoor navigation using high sensitivity GNSS, multipath is even more of a problem in these areas, thus a ‘real time’ multipath mitigation technique has many mass market applications. Significant research has been conducted in this field both from a hardware and software perspective. Hardware solutions to this problem include the use of choke-ring antennas. However, these are large, cumbersome and expensive (£2,500+). Therefore a software solution that is memory efficiency would be of significant benefit.
This research investigates the use of Artificial Immune Systems (AIS) utilised in computer science, applied to multipath error detection. In particular the deterministic Dendritic Cell Algorithm (dDCA) was tested, in order to identify and mitigate the impact of multipath on GPS data. AIS is a branch of computer science which takes principles derived from the human immune system and applies it to issues such as internet security, etc. The Dendritic Cell Algorithm was developed from the principles of how dendritic cells in the human body work in differentiating between dangerous and safe context. This algorithm has been successfully applied to internet attack identification, as well as for intruder identification in security robots.
This paper shows one of the results of initial tests using the dDCA algorithm on epoch by epoch On-The-Fly (OTF) static GPS data. The results show that the dDCA algorithm has potential benefits in the fight to mitigate multipath in GPS data.
Original languageEnglish
Title of host publicationFIG Congress 2010
Subtitle of host publicationFacing the Challenges : Building the Capacity. Sydney, Australia, 11-16 April 2010
Number of pages14
Publication statusPublished - 2010


  • Multipath
  • Dendritic Cell
  • GPS
  • Artificial immune systems


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