Cell Phone Radar

Cell Phone Radar


J-K Lam, FaberMaunsell, UK; P Lloyd, Roke Manor, UK


The Cell Phone Radar technique for monitoring traffic works by detecting cell-phone base-station transmissions reflected by an object?s surfaces. From these echoes, the type, speed and position of vehicles and pedestrian road users can be monitored.



This paper details the emerging ?Cell Phone Radar? (CPR) technique for monitoring traffic. CPR works by detecting existing cell-phone base-station transmissions reflected by an object?s surfaces. From these echoes, the type, speed and position of road users ? both vehicles and pedestrians ? can be monitored. CPR requires no special equipment on the vehicle.

It will assess the potential contribution of CPR in fulfilling policy objectives of reducing congestion, accessibility, casualty reduction, respect for the environment and economic viability.


There is more and more emphasis on informed travellers, making best use of transport networks through proactive management and safe journeys. Wide scale monitoring delivering high quality data is the cornerstone of the traffic management, charging and traveller information services that will help fulfil the policy objectives of national and international governmental bodies.

However, current sensors may:

- only monitor at a point ? such as is the case with a motorway or traffic signal loop;
- need expensive and vulnerable in-road installation;
- not work in all weathers or in poor visibility;
- be difficult to justify on trunk roads due to lower volumes;
- require specialist equipment in-vehicles (e.g. GPS receivers) and so not measure all traffic; and
- not detect all types of road users ? pedestrians as well as cars for example.

CPR could be used as an alternative to conventional traffic monitoring devices, particularly on roads that are not currently equipped. CPR could also be used to anonymously track individual vehicles for use in applications such as Origin-Destination Matrices, Active Traffic Management and CVHS.


CPR locates and characterises objects including vehicles, cycles, pedestrians, large animals, trains and so on, by detecting passive cell-phone transmissions that echo off the objects? surfaces. It does not rely on any special equipment on the object as it utilises the signals from existing cell-phone base stations. It is already being developed through the CELLDAR(TM) programme for defence, as an alternative to conventional radar, by Roke Manor Research in association with BAE Systems.

CPR looks at the difference between the signal reflected from an object and the signal received from a cell-phone base station. Unlike conventional radar, it does not transmit a signal itself and therefore needs little power and minimal infrastructure. The raw signals received are processed to determine the type, speed and position of objects. As the CPR receiver beam can be ?steered? electronically, whole lengths of roads or even networks can be monitored, rather than just single points, provided there is a clear path for the signal.

The technology comprises mobile phone and radar technology ? with the simplest version possibly being drink can sized ? with software required to process the signals to give traffic related data. The units communicate with central systems like UTMC or traffic control centres either by traditional fixed communications or through cell-phone data transmissions.


The CELLDAR(TM) deployment of CPR is a low risk solution based on off the shelf equipment, including standard mobile phone equipment. Only the signal processing software is bespoke. When a vehicle enters a detection region, cell phone transmissions are reflected by it and are detected at one or more receivers.

Each received signal is changed in frequency by a combination of the speed, position, and direction of the vehicle and also by the position of the base station and receiver. This information may be extracted from the signals providing a history of the traffic flow within the detection region.

Within the signals received are a number of features that may, given suitable development, be used to determine the type of vehicles that are within the detection region. The most obvious of these are the strength and the frequency width of the reflected signal. More subtle features are the details in the signal and the secondary reflections or multi-path.

CPR offers many advantages over existing technologies, including monitoring multiple lanes and/or roads from a single installation, it passively detects vehicles over wide area, it has a minimal impact on infrastructure, and multiple detectors could be networked together.


This paper will report on how the emerging CPR concept could assist the needs of transportation and transport policy options. Although a military version of the system should be in production in three to five years? time, research and customisation will be required for civilian transport applications.

It assesses the CPR concept?s potential applications and its suitability for practical use, will examine the business cases for each of these areas in comparison with other technologies, and will investigate how CPR could be deployed, used and operated. It will also identify the most significant practical issues likely to arise and outline how they will be overcome.


The paper will summarise the potential impact of CPR on transport in the future, including the feasibility of potential applications to road transportation needs.


Association for European Transport