Embodiments of the present invention will now be described by way of example and with reference to the drawings, in which:
From considering a known system, the inventor realised that context information relating to movement can be derived from considering the timing of a handover from one cell to another.
The example network is a Universal Mobile Telecommunications System (UMTS) terrestrial access network (UTRAN), which is a type of wideband code division multiple access (CDMA) network for mobile telecommunications. The UTRAN network is basically as shown in
Speed of movement of the mobile terminal 12 is estimated from determining the time interval between handovers from one cell to the next. This approach works because in many areas, such as well-populated areas, coverage by the network is essentially complete. Also, mobile terminals can detect cell changes.
As shown in
The instruction to handover from one cell to the next is generated by the relevant radio network controller, RNC, 8 as part of so-called network link level signalling. The instruction includes the identity of the cell to be transferred to, cell-idnew, and frequency bands to be used.
The processor 20 includes an “invalid change” filter 21 which acts to filter out data of, and so ignore, frequent changes of the form: cell A to cell B to cell A again, as can occur when the mobile terminal is relatively static near to a cell boundary. Otherwise a time interval, Δtime, is deduced where Δtime=T2−T1.
The time interval Δtime is directed to a speed estimator 24. The speed estimator uses an estimate of cell diameter to estimate speed as follows:
Speed=cell diameter/Δtime
The estimated cell diameter is set beforehand dependent on information such as whether the cell is in a rural environment or in a city. In the city, there is higher cell density and hence cell diameter is smaller. Estimated cell diameter is also set dependent on the type of network, for example in this UMTS network, estimated cell diameter is set to be larger than that which would be set for a corresponding network (not shown) of Global System for Mobiles, GSM, type.
As shown in
The context information, once derived, is shared with potential communication parties, for example through the use of the SIP event framework. Specifically, the context information is forwarded to a Presence Server, using a PUBLISH function. From there, the context information can be notified to one or more subscribing interested other users, using NOTIFY functions.
Context information is useful in selecting appropriate enhanced service offerings. For example, context information indicating “driving” might be taken as an indication that the user is a driver and hence an adult in deciding whether to send that user a particular call or message relating to an enhanced service.
In a further example (not shown) that is otherwise similar to that shown in
In a further example mobile terminal shown in
Specific cell sizes and/or longitude and latitude coordinates can be stored in the memory 322 acting as a database; alternatively if memory 322 is small, that information can be obtained by querying a network-based database (not shown).
The reader will understand that the approaches described above can generally be used in any type of wireless telecommunications network in which cell handovers by mobile terminals can be identified. For example, the approaches described above in relation to
For example, in a Wi-Fi network, cell handovers are usually mobile-initiated, but timing of cell handovers is nevertheless detectable. Information as to cell identities is provided in the control signals that are broadcast to mobile terminals on a frequency band allocated to a frequency control channel in accordance with an IEEE 802.11 standard, such as 802.11a, 802.11b, or 802.11g. The relevant information as to cell identity is the Access Point Medium Access Control, AP MAC, address (Base Station System IDentity, BSSID).
The present invention may be embodied in other specific forms without departing from its essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.