GB2536469A

GB2536469A - Communications device and method

Info

Publication number: GB2536469A
Application number: GB1504585.9A
Authority: GB
Inventors: Peter Adams Graham
Original assignee: HWM Water Ltd
Current assignee: HWM Water Ltd
Priority date: 2015-03-18
Filing date: 2015-03-18
Publication date: 2016-09-21
Also published as: GB201504585D0

Abstract

A communications device carrying a list of suitable networks is described. The device comprises a radio transceiver and a controller. The controller is operable to monitor S1 the signal strength of radio networks from which the radio transceiver is receiving signals and to establish S8 a communications session via the radio network having the strongest signal out of the list of suitable networks. The controller may also monitor the reliability of radio networks it connects to and adjust the list of suitable networks based on the monitored reliability, e.g. by storing network performance information regarding the reliability of the radio networks and basing the determination of whether to use a radio network on both the determined signal strength and the stored network performance information. In this way, the communications device is able to optimise communications based on its own radio environment, without being constrained to using inappropriate radio networks.

Description

Communications Device and Method

Field of the invention

The present invention relates to a communications device, a subscriber identity module (SIM) and a communications method.

Background to the invention

The connection of a mobile device to a radio network is controlled and authenticated via a subscriber identity module (SIM) housed in the mobile device. It is generally the SIM that permits roaming -the attachment of the mobile device to many networks, rather than being fixed to communicate via only a single network. Roaming functionality is normally controller via functionality created by the issuing network (that is, the "home" network using which the mobile device communicates by default). This functionality will generally cause the mobile device to connect via the issuing network's preferred roaming partners, which will not necessarily be the best network, for example in terms of reliability, signal strength or required functionality for data.

Roaming functionality is usually controlled via a preferred network list stored on the SIM, along with a memory of the last network connected, which will cause the device to prioritise the last connected network, even if this is no longer appropriate (due for example to a network fault, or a change in the radio environment within which the mobile device is located). This problem is particularly bad for a static device, which cannot be easily moved to obtain a better signal.

Embodiments of the present invention seek to address the above problems.

Summary of the invention

According to an aspect of the present invention, there is provided a communications device carrying a list of suitable networks, the device comprising a radio transceiver and a controller; wherein the controller is operable to monitor the signal strength of radio networks from which the radio transceiver is receiving signals, and to establish a communications session via the radio network having the strongest signal out of the list of suitable networks. In this way, the communications device is able to optimise communications based on its own radio environment, without being constrained to using inappropriate radio networks.

The device may carry a Subscriber Identity Module (SIM), the list of suitable networks is stored on the SIM. Alternatively, the list of suitable networks may be stored on the communications device.

The controller may periodically determine the signal strength of the radio networks and switch to a communications session using a different radio network, if the different radio network is determined to have a stronger signal than the radio network currently being used.

The controller is operable to delay an attempt to connect to a radio network, in order to alleviate congestion which might occur if a high-signal strength radio network suddenly becomes available, prompting multiple communications device to attempt to connect to it. Preferably, the delay is a random, or semi-random delay, to reduce the likelihood of multiple communications devices delaying by the same amount of time.

Preferably, if the attempt to connect to the radio network is unsuccessful, the controller attempts to connect again after a further delay, the further delay being longer than the original delay. Preferably, the delay comprises a fixed time component and a variable time component, the fixed time component increasing following an unsuccessful connection attempt. Accordingly, if congestion causes a connection failure, congestion will become less likely on the second attempt due to the greater wait time before retrying. The fixed time component may be able to increase up to (but not beyond) a maximum value. This prevents the retry wait time becoming too long.

The fixed time component is preferably reset upon a successful connection, so that a short wait time is again used when the communications device switches to using yet another radio network.

Preferably, the controller is operable to monitor the reliability of radio networks it connects to, and to adjust the list of suitable networks based on the monitored reliability. Accordingly, the communications device is able to utilise its own experience of the reliability of a particular radio network influence the selection of radio networks in the future.

The step of adjusting the list of suitable networks may comprise removing an unreliable radio network from the list of suitable networks. Alternatively, the step of adjusting the list of suitable networks may comprise storing network performance information regarding the reliability of the radio networks. In this case, the controller may be operable to determine whether to use a radio network based both on the determined signal strength and the stored network performance information. Alternative solutions are also possible. For example, the list of suitable networks could be arranged in multiple tiers, for example an upper tier of "reliable" networks which will be preferentially selected over a lower tier of "unreliable" networks (which might only be used if the reliable networks are unavailable, or at very low received signal levels). Promotion of networks to a higher tier or demotion of networks to a lower tier could thus occur based on radio network performance as observed by the communications device.

As examples, the network performance information may be based on the communications device experiencing communications sessions being dropped by the radio network, or on the quality of service experienced by the communications device when using the radio network.

The controller may be operable to override an external request for the communications device to connect on a network. The override might be to completely ignore the request, or might be to restrict the request to radio networks present on the list of suitable networks defined in the SIM.

According to another aspect of the present invention, there is provided a subscriber identity module comprising: control logic, for causing a communications device into which the subscriber identity module is loaded to monitor the signal strength of radio networks from which the communications device is receiving signals; and a network information store, defining a list of suitable networks; wherein the control logic causes the communications device to establish a communications session via the radio network having the strongest signal out of the list of suitable networks.

It will be appreciated that the functions described herein can be provided either via device firmware, or via an application running on the SIM (whether card type or chip type SIM). The implementations in these two instances would differ, but the concept remains the same. The functions described above could also be software controlled, in which case a computer program for controlling the operation of a communications device is also envisaged as an aspect of the present invention.

According to another aspect of the present invention, there is provided a method of controlling the establishing a communications session between a communications device and a radio network, comprising the steps of: monitoring the signal strength of radio networks from which the communications device is receiving signals; and establishing a communications session via the radio network having the strongest signal out of a list of suitable networks carried by the communications device.

Detailed description

The invention will now be described by way of example with reference to the following Figures in which: Figure 1 schematically illustrates a communications device within the coverage area of three radio networks; Figure 2 schematically illustrates a network priority list stored on the SIM of the communications device of Figure 1; Figures 3A and 3B schematically illustrate a network hopping method of operating the communications device of Figure 1; and Figure 4 schematically illustrates a network performance monitoring process. Referring to Figure 1, a communications device 10 is within the coverage area of a first radio access network 22, a second radio access network 24 and a third radio access network 26. The communications device 10 receives radio signals 23 from the radio access network 24, radio signals 25 from the radio access network 24, and radio signals 27 from the radio access network 26. The radio signals 27 are relatively weak, the radio signals 23 are moderately strong, while the radio signals 25 are very strong. The communications device 10 comprises a subscriber identity module (SIM) 12, transceiver circuitry 16 for receiving and transmitting radio signals via an antenna, a base band controller 14 for controlling communications via the transceiver circuitry 16, and an external controller 18 for controlling other functions of the communications device 10 or another device of which the communications device 10 is a part. The baseband controller 14 or the external controller 18 is able to control communications to and from the communications device in dependence on measured signal strength (at the transceiver circuitry 16), information held in the SIM 12, and its own internal logic/algorithms. The communications device 10 may for example be a machine to machine (M2M) device, such an a communications component of industrial, commercial or consumer device, permitting that device to be controlled by, and to report back to, an external device without relying on a wired communications link. Alternatively, the communications device 10 may be a portable electronic device such as a mobile telephone

or tablet.

Referring to Figure 2, an exemplary network priority list is shown. The network priority list may be stored on the SIM 12, or may alternatively be stored in a memory on the communications device itself, or as part of either the base band controller 14 or the external controller 18. The network priority list stores, for each of a set of suitable radio networks, an indication of the performance of those networks. Unsuitable networks, such as those which do not have suitable functionality for the communication requirements of the device 10, are not included in the list. The performance information may simply be a performance rating (as illustrated in Figure 2, using star ratings, with a 3 star rating indicating the best radio network performance, and a 1 star rating indicating the worst radio network performance), or may include performance metrics permitting the controller 14 or 18 to make a more informed decision as to which network is the most appropriate in the circumstances. The performance of the radio networks is assessed by the communications device 10 itself on a periodic or ongoing basis, and the network priority list stored in the SIM 12 (or elsewhere) is updated to reflect the monitored performance. The performance information may be modified if a particular radio network drops communications sessions, is determined to be regularly unavailable, has a tendency to reject connection requests, suffers from a poor signal to noise ratio, or based on any other suitable performance metric which can be assessed by the controller 14 or 18. For example, if the mobile device is currently communicating using the "abc" radio network, and the communications session is unexpectedly terminated, the controller 14 may downgrade the performance information from 3 stars to 2 stars.

Referring to Figures 3A and 3B, a control flow carried out by the controller 14 is shown. At a step S1, which may be carried out constantly, or periodically, the signal strength of received radio signals (for example from the radio networks 22, 24, 26 in Figure 1) is monitored at the communications device 10. The signal strength of the radio network currently being used by the communications device 10 is compared with the signal strength of the other radio networks at a step S2. If it is determined that the signal from the currently used radio network is the strongest, there will be no need to switch to a different network, and the process returns to the step S1 for further monitoring of signal levels. If it is determined that the signal from the currently used radio network is not the strongest, and other available networks are stronger, then the process moves on to a step S3, where the radio network from which the strongest signals are detected is selected for consideration. It should be noted that signal strength may only be monitored for radio networks listed in the network priority list on (for example) the SIM 12, or otherwise obtained from the network provider associated with the SIM, since only these networks are considered appropriate. It will be appreciated that radio networks may be added or removed from the network priority list, for example in response to external instructions received via the radio transceiver 16. At a step S4, the controller 14 looks up the performance of the strongest radio network in the network priority list (for example from the SIM 12). It is then determined at a step S5 whether the performance of the radio network is adequate, and if not, that radio network is rejected at a step S6. The decision may be based only on the performance of that radio network, or may be based also on the performance of the current radio network, or even based on the performance of all radio networks from which the communications device 10 is currently receiving radio signals. If the radio network is rejected, then the process returns to the step S3, where the next strongest radio network is selected for consideration. If at the step S5 the radio network under consideration is determined to have an adequate performance, then the communications device 10 will attempt to connect to this radio network. However, before attempting connection, the communications device 10 will delay at a step S7. Preferably, the duration of the delay is random, or at least partly random. Preferably, the duration of the delay has a random component and a non-random component. Populations of devices that attempt to register simultaneously, which can happen when power or network faults are resolved, may cause network related failures due to congestion. The random component is provided so that multiple communications devices do not attempt to connect to a radio access network at the same time, which might lead to congestion. Following the delay, the communications device 10 attempts to connect to the new radio network at a step S8. It is then determined at a step S9 whether the connection process was successful. If it is determined at the step S9 that the communications device 10 was unsuccessful in connecting to the new network, then the non-random component of the delay duration is increased (subject to an optional maximum), and the process returns to the step S7 where the communication device 10 delays retrying the connection procedure. The delay this time is longer (due to the step S10). The increase in the delay time helps to reduce congestion where multiple devices are all trying to connect to the network at the same time. If at the step S9 it is determined that the connection to the new radio network has been successful, then the delay period for the purposes of the step S7 is reset to its original value at a step 311, and the communications device 10 then proceeds to communicate using the new radio network at a step S12. The process then returns to the step Si for further monitoring of the signal strength. In this way, the communications device 10 is able to hop between networks to maintain the strongest radio connection.

Referring to Figure 4, a process of keeping the network priority list updated with performance information for radio networks is shown. At a step S21, the communications device 10 monitors the performance of the network it is currently attached to. Such monitoring may track signal strength consistency, signal to noise ratios and any other quality metrics, or may simply involve tracking occurrences when a communications session involving that radio network is dropped by the network. At a step S22, it is determined either in response to a call being dropped, in an ongoing manner when observing communications performance, or periodically -whether the network priority list needs to be updated to reflect the monitored performance of the network. If not, then the process returns to the step S21 for further monitoring. If at the step S22 it is determined that the network priority list needs updating, then at a step S23 the controller 14 updates the network performance information in the SIM 12 to reflect the change in performance of the radio network. In this way, the communications device 10 is able to "learn" of the performance of radio networks which it is in the coverage area of, and can use this information when network hopping to avoid unreliable radio networks. This is particularly relevant to M2M devices which have relatively static radio environments, since observed poor radio network performance is likely to be a good indicator of further radio network performance (this is less likely to be the case for a mobile device, where the radio environment is constantly changing).

It will be appreciated that, in some circumstances, it may be desirable to switch networks from a current network to another network even if the new network exhibits the same, or even a weaker, signal strength than the current network, for example if the new network is indicated by the network priority list to be more reliable that the current network. More generally, the selection of networks could be determined based on any logical or algorithmic basis utilising signal strength and preferably also device-monitored historical network performance. Generally, it will be appreciated that the network performance information is indicative of the reliability of a radio network as experienced by the communications device.

By way of general summary, it will be appreciated from the above that the SIM (or the device) will run an application that periodically monitors the signal strength of all the network signals it can receive. It will force connection to the strongest signal that matches its own list of suitable network identifiers. The connection will be subject to a small random timing variance, to prevent simultaneous presentation of multiple devices to the radio network. The timer will work by using a fixed time plus a random time. If the connection fails, then a retry will use an increased fixed time element to further delay connection attempts. The fixed time will increase with each failure according to a specific algorithm and maximum value. A successful connection will reset the timer. Periodically the application will rescan the network signals, and reconnect to the strongest network. The application will keep historic information on the networks it has used, and use this to adjust its own network priority list, attempting to avoid networks that appear unreliable. If any other system requests a network reconnection, for example the M2M device if the application is SIM based, or the issuing network preferred network list, then the application will override this and connect according to its own algorithms.

Claims

CLAIMS1. A communications device carrying a list of suitable networks, the device comprising: a radio transceiver; and a controller; wherein the controller is operable to monitor the signal strength of radio networks from which the radio transceiver is receiving signals; and to establish a communications session via the radio network having the strongest signal out of the list of suitable networks.
2. A communications device according to claim 1, wherein the device carries a Subscriber Identity Module (SIM), and wherein the list of suitable networks is stored on the 15 SIM.
3. A communications device according to claim 1, wherein the list of suitable networks is stored on the communications device.
4. A communications device according to any preceding claim, wherein the controller periodically determines the signal strength of the radio networks and switches to a communications session using a different radio network, if the different radio network is determined to have a stronger signal than the radio network currently being used.
5. A communications device according to any preceding claim, wherein the controller is operable to delay an attempt to connect to a radio network.
6. A communications device according to claim 5, wherein the delay is a random, or semi-random delay.
7. A communications device according to claim 6, wherein if the attempt to connect to the radio network is unsuccessful, the controller attempts to connect again after a further delay, the further delay being longer than the original delay.
8. A communications device according to claim 6 or claim 7, wherein the delay comprises a fixed time component and a variable time component, the fixed time component increasing following an unsuccessful connection attempt.
9. A communications device according to claim 8, wherein the fixed time component is able to increase up to a maximum value.
10. A communications device according to claim 8, wherein the fixed time component is reset upon a successful connection.
11. A communications device according to any preceding claim, wherein the controller is operable to monitor the reliability of radio networks it connects to; and to adjust the list of suitable networks based on the monitored reliability.
12. A communications device according to claim 11, wherein the step of adjusting the list of suitable networks comprises removing an unreliable radio network from the list of suitable 15 networks.
13 A communications device according to claim 11, wherein the step of adjusting the list of suitable networks comprises storing network performance information regarding the reliability of the radio networks, and wherein the controller is operable to determine whether to use a radio network based both on the determined signal strength and the stored network performance information.
14. A communications device according to claim 13, wherein the network performance information is based on the communications device experiencing communications sessions being dropped by the radio network.
15. A communications device according to claim 13, wherein the network performance information is based on the quality of service experienced by the communications device when using the radio network.
16. A communications device according to any preceding claim, wherein the controller is operable to override an external request for the communications device to connect on a network.
17. A subscriber identity module comprising: control logic, for causing a communications device into which the subscriber identity module is loaded to monitor the signal strength of radio networks from which the communications device is receiving signals; and a network information store, defining a list of suitable networks; wherein the control logic causes the communications device to establish a communications session via the radio network having the strongest signal out of the list of suitable networks.
18. A method of controlling the establishing a communications session between a communications device and a radio network, comprising the steps of: monitoring the signal strength of radio networks from which the communications device is receiving signals; and establishing a communications session via the radio network having the strongest signal out of a list of suitable networks carried by the communications device.
19. A communications device, subscriber identity module or method of establishing a communications session substantially as hereinbefore described with reference to the accompanying drawings.