E-OTD Location Technology in Trouble
(21/10/2002, Ledbury, UK)
Problems in meeting E-911 performance requirements in the US, coupled with a lack of commitment from European operators, mean that E-OTD wireless location technology faces troubled times ahead. BWCS industry white paper The Last Known Location of E-OTD (available from BWCS.com shows that many question marks still hang over E-OTD (Enhanced Observed Time Difference) technology in terms of its positioning accuracy, reliability and cost.
In the US the leading GSM operators AT&T Wireless, Cingular Wireless and VoiceStream (T-Mobile) have chosen E-OTD to meet positioning accuracy requirements laid down in the Federal Communication Commissions (FCCs) E-911 mandate. However, field tests of E-OTD carried out by these three operators indicate that it falls short of accuracy levels set out by the FCC for handset-based positioning solutions.
BWCS Managing Director Graham Wilde said: Problems with E-OTDs accuracy are now causing serious concern among the emergency services community in the US. Tests carried out by VoiceStream found E-OTD accuracy to be 75 metres for 67% of calls and 259 metres for 95% of calls, compared to the FCC stipulation of 50 metres for 67% of calls and 150 metres for 95% of calls.
Wilde said, Its impossible to say what the root causes of E-OTDs poor performance are, but we suspect that its reliance on handsets to collect signals from base stations and transfer that data to network LMUs [Location Measurement Units] may be a large component. Limitations on the performance capability of handsets compared with network-based equipment, could be a major part of the problem.
If E-OTD technology cannot be improved to meet the E-911 mandate by the October 2003 deadline set by the FCC, the US GSM operators will face hefty fines and may be forced to look at alternative positioning technologies. A recent FCC submission by AT&T Wireless stated that it may not be able to meet the future deadline. Supporting submissions from Nokia warned that AT&T may be forced to make changes to its network planning and antenna configuration in order to bring E-OTDs performance up to the required standard.
In an effort to insure themselves against the possible failure of E-OTD, both AT&T Wireless and Cingular Wireless have announced plans to trial an alternative location technology, called U-TDOA (Uplink Time Difference of Arrival). Wilde said, This is the most concrete evidence that AT&T Wireless and Cingular believe they may not be able to make it with E-OTD. Its a highly significant move.
In Europe, a BWCS survey of mobile operators found many to be concerned about the cost of rolling out the technology. Wilde said: There is no E-911 mandate in Europe, so mobile operators are looking at location services from a purely commercial perspective. At the moment most of them are using basic Cell-ID positioning because its cheap. While the operators acknowledge that there is a correlation between positioning accuracy and location service revenues, they have expressed misgivings about the cost and performance of E-OTD.
About BWCS
BWCS is a leading wireless telecommunications consultancy, based in the UK and operating worldwide. We work with wireless operators, equipment vendors, wireless software providers and major corporate users on wireless communications strategy.
For more information, please visit our website at www.BWCS.com To contact the authors, please e-mail Graham.Wilde@bwcs.com. .
For further information on this report, please call BWCS on
+44 (0)1531 634326 or visit our website at BWCS.com
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