Communication system

Abstract

A communication system comprises a plurality of communication devices comprising one or more host communication devices. A given host communication device is configured to establish a plurality of communication channels to transfer messages via message routing circuitry between the given host communication device and a plurality of member communication devices forming a communication group of the plurality of communication devices. The plurality of communication devices are prohibited from transferring messages via the message routing circuitry other than via a communication channel established by the one or more host communication devices.

Description

[0001] COMMUNICATION SYSTEM

[0002] The present technique relates to the field of communication systems.

[0003] At least some examples provide a communication system, comprising a plurality of communication devices comprising one or more host communication devices; wherein a given host communication device is configured to establish a plurality of communication channels to transfer messages via message routing circuitry between the given host communication device and a plurality of member communication devices forming a communication group of the plurality of communication devices; and the plurality of communication devices are prohibited from transferring messages via the message routing circuitry other than via a communication channel established by the one or more host communication devices.

[0004] At least some examples provide a communication device configured exchange messages with one or more further communication devices via message routing circuitry; wherein the communication device is configured to establish a plurality of communication channels to transfer messages via message routing circuitry between the communication device and a plurality of member communication devices forming a communication group of the one or more further communication devices; and the communication device is prohibited from transferring messages via the message routing circuitry other than via a communication channel established by a host communication device.

[0005] At least some examples provide a communication method, comprising: providing a plurality of communication devices comprising one or more host communication devices; establishing a plurality of communication channels to transfer messages via message routing circuitry between the given host communication device and a plurality of member communication devices forming a communication group of the plurality of communication devices; and prohibiting transfer of messages between the plurality of communication devices other than via communication channels established by the one or more host communication devices.

[0006] Further aspects, features and advantages of the present technique will be apparent from the following description of examples, which is to be read in conjunction with the accompanying drawings, in which:

[0007] Figure 1 illustrates a plurality of communication devices and message routing circuitry;

[0008] Figure 2 schematically illustrates communication channels, established by a host communication device, within a communication group;

[0009] Figure 3 schematically illustrates a broadcast message issued by the host communication device; Figure 4 schematically illustrates a member message issued by a member communication device;

[0010] Figure 5 schematically illustrates a communication system comprising a plurality of communication devices, and communication channels between the communication devices;

[0011] Figure 6 is a ladder diagram illustrating a host communication device transmitting a key message to a target member communication device;

[0012] Figure 7 schematically illustrates an example communication device;

[0013] Figure 8 schematically illustrates an example of message routing circuitry;

[0014] Figure 9 is a flow diagram illustrating a method of using a communication system; and

[0015] Figure 10 is a flow diagram illustrating a method of transmitting a key message via a communication system.

[0016] A communication system comprises a plurality of communication devices which may exchange messages with each other. The communication devices are not particularly limited, and may for example include mobile devices, personal computers, and so on. The messages are also not particularly limited and may include audio, text, video, and so on.

[0017] Within a communication system, it can be useful to support transmission of messages within a group of communication devices. For example, a particular communication device in a group may transmit a particular message to each of the other devices in the group. Grouping of communication devices can allow information to be communicated quickly among the members of the group without requiring messages to be individually sent to each member of the group. Communication groups may provide a useful mechanism to transmit messages to a selected group of other communication devices, but communication systems typically also permit communication devices to transmit messages individually to other communication devices in the communication system.

[0018] The inventor has realised that existing communication systems may be associated with several disadvantages. First, permitting communication devices to transmit messages to, in general, any other communication device within the communication system may result in large numbers of messages being transferred between communication devices and hence lead to high bandwidth consumption of message routing circuitry responsible for transferring messages between the communication devices. In certain applications, the message routing circuitry may have a limited bandwidth, and heavy usage of this limited bandwidth can result in delays to the transfer of messages within the communication system. Delayed transfer of messages may be particularly significant in safety critical applications, where prompt transmission of safety critical messages may be required to ensure that users of the safety critical communication system are provided with safety critical information as soon as possible.

[0019] Additionally, by supporting communication groups where members are in general permitted to transmit messages to the other members of the group, grouping of communication devices may provide communication links between communication devices which a user would prefer to keep separate. One approach may be to provide separate groups to keep certain communication devices separate, but this may require a message to be sent separately to the separate groups, both delaying transmission of messages and increasing a burden on the sender. This can be a particular issue in safety critical applications, where any delay in transmitting a message may increase a risk to users of the safety critical communication system.

[0020] According to the present techniques, a plurality of communication devices comprise one or more host communication devices, wherein a given host communication device is configured to establish a plurality of communication channels to transfer messages via message routing circuitry between the given host communication device and a plurality of member communication devices forming a communication group of the plurality of communication devices. The plurality of communication devices are prohibited from transferring messages via the message routing circuitry other than via a communication channel established by the one or more host communication devices.

[0021] Hence, according to the present techniques a communication system is provided in which communication devices may be grouped to permit messages to be transmitted to a communication group. Messages may only be transmitted using communication channels established by a host communication device, and hence messages may only be transmitted within communication groups established by a host communication device. As the host communication device does not establish communication channels between member communication devices when establishing the communication group, messages may only be transmitted within a communication group between the host communication device and a member communication device, and not between member communication devices. Hence, a communication system according to the present techniques enables communication groups to be established without establishing communication channels between members of the communication group, and without permitting communication devices to otherwise communicate.

[0022] A communication system according to the present techniques may therefore provide a reduction in bandwidth consumption by preventing transfer of messages between communication devices other than via communication channels established by host communication devices. This can enable messages to and from host communication devices to be transmitted with a reduced delay, which can lead to improved transfer of important messages such as safety critical messages.

[0023] In some examples, the plurality of communication channels established by the given host communication device do not permit messages to be transferred between the plurality of member communication devices of the communication group. Therefore, a communication system according to the present techniques also allows communication devices to be placed in a communication group, and hence for messages to be transmitted to those devices with reduced delay, even when there is a requirement to prevent communication between those communication devices. As has been discussed above, in some examples the plurality of communication devices may provide a safety critical communication system for transferring safety critical messages. The present communication system prohibits transfer of messages between communication devices other than to and from a host communication device. This can reduce the ability for certain communication devices to exchange messages (e.g., where there is no safety-related reason for those communication devices to communicate). In safety critical environments, the use of a communication system for conversation may increase a number of distractions available to a user, where such distractions may be associated with an increased level of risk. Certain operators might therefore prohibit the use of such communication systems to reduce the risk of distraction, but this can lead to the problem that without the communication system the transfer of safety critical information may be delayed, also increasing risk. Providing a communication system according to the present approach enables safety critical messages to be transmitted and received quickly, and hence allows safety to be increased. Restricting communication between communication devices such that communication may only be to or from a host device via established channels may reduce distractions which might otherwise arise from use of the communication system.

[0024] It will however be appreciated that the advantages associated with the present technique may find many applications, and may not be limited to safety critical applications. In general, the ability to define communication groups whilst restricting other communication may be beneficial in a range of applications, such as communication within an educational institution (where groups of students may be established by teachers, prohibiting communication between students but enabling efficient communication between students and a teacher).

[0025] In some examples, the given host communication device may be configured to issue a broadcast message to the plurality of member communication devices of the communication group. The broadcast message may for example be sent to each member of the communication group simultaneously, hence permitting information to be communicated quickly to the member communication devices of the communication group. Supporting broadcast messages may enable important messages, such as safety announcements or alerts, to be transmitted to a relevant group of communication devices which may be affected by the important message even in cases where that relevant group comprises communication devices which should be prevented from communicating with each other. In a safety critical context this can lead to an overall increase in safety because important messages can be received more quickly by those relevant communication devices than if the host communication device were required to send several separate messages to communication devices which should be prevented from communicating with each other.

[0026] In some examples, a given member communication device is configured to issue a member message to the host communication device. Hence, the communication channels established between a host communication device and a member communication device may permit messages to be sent both from the host communication device to the member communication device and from the member communication device to the host communication device. The communication groups may therefore determine which communication devices are permitted to send messages to the host communication device. Such two-way communication groups may find particular use in safety critical applications, as this provides a route for a member communication device to report hazards to the host communication device.

[0027] As discussed above, a communication system according to the present techniques enables communication channels to be established by host devices. In some examples, host devices could be a certain predefined set of communication devices, and hence enabling communication channels to only be established by host devices may prevent two devices which are not host communication devices from communicating with each other. However, in other examples each of the plurality of communication devices may be permitted to act as a host device, and hence a host device may merely be defined with reference to a particular communication group rather than being a distinct type of communication device. In such cases it may still be desired to prevent any communication device arbitrarily establishing communication groups with any other communication device. Hence, in some examples, the plurality of communication devices may each be associated with privilege information, and a prospective host communication device may be configured to perform a comparison of host privilege information associated with the prospective host communication device and member privilege information associated with a given member communication device to determine whether the prospective host communication device is permitted to establish a communication group comprising the given member communication device. Hence, a communication group may only be permitted to establish communications groups with certain communication devices.

[0028] The privilege information is not particular limited. In some examples, the privilege information associated with a particular communication device may represent some attribute associated with that communication device, such as the type of communication device, where an operator of the communication system may define rules which indicate whether a prospective host communication device having a first attribute is permitted to establish a communication group comprising a communication device having a second attribute.

[0029] However, in other examples, the privilege information may comprise an indication of a device privilege level, wherein a given communication device may be prohibited from establishing a communication group comprising member communication devices having a higher device privilege level than themselves, and in some cases prevented from establishing a communication group comprising member communication devices having the same device privilege level as themselves. The privilege level may for example be represented by a numerical privilege value or otherwise (such as by a job title associated with the user of the device). By associating communication devices with a privilege level, a hierarchical communication system can be established in which communication devices may be permitted to establish communication groups downwards in privilege level to communicate (both sending and receiving messages) with devices at lower privilege levels, whilst preventing devices from establishing communication channels with devices at the same or higher privilege levels. Hence, within such a hierarchical communication system, communication may be permitted downwards and (in limited cases) upwards in hierarchy but not sideways. Whilst the decision about which privilege level should be associated with each communication device is a decision to be made by the operator of the communication system, supporting the use of privilege levels to control the establishment of communication channels between devices can provide a particularly effective mechanism for permitting establishment of communication channels within a communication system. A communication device at a given privilege level may have no control over which more privileged devices it may transfer messages to (this being decided those more privileged devices in their decision to establish communication groups) whilst having freedom to choose which less privileged devices it may send messages to. Hence, messages between devices of the same privilege level or upwards in privilege level can be suppressed whilst supporting free flow of information downwards in privilege.

[0030] It will be appreciated that in some examples, the privilege information may include an indication of a device privilege level and additional information, meaning that a given device may not have complete freedom about which lower level devices it may communicate with.

[0031] In some examples, the message routing circuitry for transferring messages between communication devices may comprise history storage circuitry configured to maintain a message record of messages transferred within the communication group. The message record may include, for example, an indication of which devices received a particular message, a time at which a particular messages was sent and / or received, the data content of messages, whether or not such messages were acknowledged, and so on. As discussed elsewhere, the present communication system may be particularly effective in safety critical applications. In such safety critical applications, a message record may be important for compliance purposes and for post hoc analysis of safety practices, e.g., following an accident or near-miss, to identify an order of events and potentially enable processes to be improved in future. By configuring the message routing circuitry of the communication system to maintain the message record, this allows the message record to be maintained independent of individual communication devices (and hence maintained even if those devices are damaged or lost). The message record may also be made available to an operator of the communication system via the message routing circuitry. For example, a host of a particular communication group may be permitted to view the message record for that communication group, and / or a communication device having a privilege level above a threshold level may be permitted to view a message record associated with devices below that threshold level, and so on.

[0032] In some examples, a communication device may be configured to issue a key message to one or more target member communication devices in the communication group, the key message requesting an acknowledgement from the one or more target member communication devices. For example, the given host communication device may issue a key message as a broadcast message or otherwise to member communication devices, or a member communication device may issue a key message to the host communication device. The key message is not particularly limited, but may for example be used for certain more important messages where acknowledgement of that message might enable the sender communication device to obtain a guarantee that certain information has been received by a receiver communication device. The given host communication device may in some examples broadcast the key message to each member communication device of the communication group, although in other examples a key message may be transmitted to a selection of one or more target communication devices. Supporting a key message may provide an improved communication system because it can enable communication devices to determine whether or not sent messages have been received by the target communication device, and hence can allow a user of a communication device to determine when a message has not been received and take appropriate action, such as by using a second form of communication to transfer the key message.

[0033] In some examples, every message could be treated as a key message requesting an acknowledgement. In other examples only a subset of messages may be key messages, which may reduce an amount of traffic handled by the message routing circuitry (e.g., reducing the requirement to handle acknowledgement messages from target communication devices to the host communication device). For example, one or more bits in a header packet may indicate whether the message is a key message or not, and this may prompt different handling by the target communication device.

[0034] In some examples, an acknowledgement may be issued automatically from a target device when that target device receives the key message or displays the key message to a user, and hence can provide a guarantee that the message was received by the target communication device. In other examples, a given target member communication device may be configured to issue the acknowledgement of the key message in response to an acknowledgement input from a user. The user input is not particularly limited, but by issuing the acknowledgement in response to a user input the communication system may provide a stronger guarantee that information included in the key message has been understood by the user of the communication system. This can enable the communication system to be used to track a flow of information to users of the communication system and provide stronger guarantees that key information has been understood by users. Such acknowledgement may be particularly beneficial in safety critical applications, as this can allow a user responsible for the safety of a team of people to issue safety critical messages to that group of people and receive an active acknowledgement that the information has been understood, which can lead to an increase in an overall level of safety which may be provided through use of the communication system. In some examples, the given target member communication device may be configured to suppress issuing the acknowledgement in response to an acknowledgement input from a user provided before expiry of a delay period following presentation of the key message to the user. Hence, in some examples, the point at which the content of the key message is presented to the user (e.g., displayed on a screen) may begin a delay period, and the target communication device may be configured to issue an acknowledgement only in response to a user input received after that delay period has expired. Supporting this feature may reduce the likelihood of messages being accidentally acknowledged (e.g., if the user input is provided inadvertently whilst a message is being opened), or otherwise acknowledged before enough time has passed to have processed the content of the key message. Hence, acknowledgements within communication system supporting this feature may provide a stronger guarantee that the key message has been understood by a user of the target member communication device. It will be appreciated that the length of the delay is not particularly limited and may be defined by a system designer.

[0035] In some examples, a host communication device may be configured to add or remove one or more member communication devices to or from a communication group. Hence, a host communication device may be able to establish or remove one or more communication channels even after a communication group has been established. This can support dynamic assignment of communication devices into communication groups, which can provide a more flexible communication system.

[0036] In some examples, one or more of the plurality of member communication devices in the communication group may be configured to transmit geolocation information to the given host communication device. For example, a member communication device may be configured to transmit geolocation information identifying the location of that member communication device to the host communication device. Hence, within a communication group established by a host communication device, that host communication device may be provided with information indicating the location of the member communication devices. This may be particularly advantageous in a safety critical application, where the host communication device may be responsible for making safety decisions regarding users of the member communication devices. Transmitting location information to the host communication device using the communication system can allow the host to determine, for example, whether one or more of the member communication devices are in a location associated with a particular hazard, which member communication device may be best positioned to perform a certain task, and so on.

[0037] The message routing circuitry may transfer messages between the plurality of communication devices in various ways. For example, messages may be transmitted via the internet and a wired or wireless network. In some examples, the message routing circuitry may be configured to transfer certain messages between a host communication device and a member communication device at least partially using a mobile network. As discussed above, the communication devices are not particularly limited. In some examples, the plurality of communication devices may comprise at least one mobile device. The mobile device may provide the functionality of the communication device described herein by executing software. For example, a mobile device may be connected to the communication system via an application executing on that mobile device, and the application may provide access to the communication channels within the communication system.

[0038] The content of the messages transferred between a host communication device and a member communication device are not particularly limited. In some examples, a message comprises at least one of: text, image, video, audio, and document data. The communication device may present the message to a user visually or audibly or both.

[0039] In some examples, the given host communication device may also be a member communication device for a further communication group. Hence, it will be appreciated that the plurality of communication devices are not exclusively a host communication device or a member communication device, but communication devices may be either or both a host communication device and a member communication device.

[0040] In some examples, the given host communication device may be configured to establish two or more independent communication groups. This can enable broadcast messages to be sent by the host communication device to separate selections of member communication devices. It will be appreciated that two independent communication groups may in some examples comprise one or more of the same member communication devices.

[0041] Particular examples will now be discussed with reference to the accompanying Figures.

[0042] Figure 1 illustrates a plurality of communication devices 4, 6, 8, and message routing circuitry 2. The communication devices may include (either individually or in combination) personal computers, mobile phones, tablets, and so on. The communication devices have a user interface to enable a user to send and receive messages to and from other communication devices within the communication system. Message routing circuitry, for example including a message routing server and one or more networks, enables said messages to be transferred from one communication device to another communication device. Although it will be appreciated that the message routing circuitry 2 is provided, the remaining Figures may not explicitly show the message routing circuitry for ease of illustration. It will be appreciated that the number of communication devices is not particularly limited, and may be varied throughout the lifetime of a communication system as devices are enrolled or removed.

[0043] Figure 1 illustrates roles which may be taken by individual communication devices within one example communication group within the communication system. For a particular communication group, one communication device is a host communication device 4 (referred to below as a host 4), while other communication devices in the communication group are member communication devices 6 (or a member 6), and communication devices outside the communication group are non-member communication devices 8. A given communication device may, for different communication groups, act as either a host communication device or a member communication device, and hence the plurality of communication devices may be configured to act as both. It will be appreciated that whilst a particular communication device may be a nonmember device 8 for a particular communication group, that communication device may be a host 4 or member 6 of a different communication group in the communication system.

[0044] Figure 2 schematically illustrates the communication channels, established by a host communication device 4, within a communication group. It will be seen that a communication channel is established (via the message routing circuitry 2) between the host communication device 4 and each member communication device 6, but not between the member communication devices 6. Hence, establishing a communication group enables the host communication device to exchange messages with each of the member communication devices, but does not enable those member communication devices to exchange messages with each other.

[0045] One example application for such a communication system is to exchange safety critical messages. A particular example of a safety critical application is exchanging safety critical messages relating to a railway, the communication system for example being operated by a train operator or a station operator (which in some scenarios may be the same entity). In this scenario, certain individuals may be responsible for managing safety of different aspects of the railway, and those individuals may be users of a safety critical communication system. For example, a set of responsible managers may include a user responsible for managing safety on board a train, a user responsible for managing safety of the public-facing parts of a station, a user responsible for managing safety of non-public-facing parts of the station (e.g., the tracks around the station), and so on as well as a (e.g., more senior) user responsible for overall safety of a particular area. Several further users may report to the responsible managers, and include station staff, engineering staff, and train staff for example. It may be important for responsible managers to send routine safety information to certain groups of users. For example, a station manager may wish to send information regarding a new safety procedure to the engineering staff at a station. It may also be important for responsible managers to send critical safety information quickly to certain groups of users. For example, the station manager may wish to send information regarding an emergency relating to a train to the engineering staff. In addition, it can be important that users are able to report safety critical information to a more senior member of staff. For example, it may be important that engineering staff are able to report a hazard to the station manager, who is able to report that hazard to their manager, and so on.

[0046] Within such a scenario, it may be important for a communication system to support grouping of messages. As discussed above, this can for example enable messages to be sent to a group of affected staff quickly and easily.

[0047] It may also be important that certain users are not able to send messages to each other. For example, this may be important to reduce the ability for the communication system to act as a source of distractions, to prevent communication between users which are for other reasons required to be kept separate (e.g., due to an information barrier within an organisation, or because those users are associated with competitors, etc.), and this can also reduce traffic on the communication system and hence increase the speed at which safety critical messages can be transmitted via the communication system.

[0048] Hence, the communication system may support groups such as those illustrated in Figure 3, which enable a host 4 to transmit messages to a group of members 6, and enable those members 6 to transmit messages to the host 4, but may prevent those members 6 from communicating with each other. The communication system may also prevent communication other than via communication channels within such groups, meaning that the members 6 are unable to communicate directly outside of the communication groups.

[0049] Within the railway example, a communication group may for example comprise a host communication device used by the station manager and a number of member communication devices used by engineering staff, to allow safety messages relating to a station to be communicated to the engineering staff and allow the engineering staff to report hazards to the station manager, but not communicate with each other. A separate communication group may comprise a host communication device used by a train manager and a number of member communication devices used by train staff. A further communication group may comprise a host communication device used by a more senior manager and member communication devices used by the station manager and train manager.

[0050] By establishing such groups, effective communication can be achieved between various users relating to the railway, as will be discussed in further detail below. It will be appreciated that the use of the present communication system in the context of a railway is merely an example, and the present communication system provides the advantages discussed herein across a range of contexts, and for example when used for communication within a range of different organisations across several different sectors.

[0051] Figure 3 schematically illustrates a broadcast message issued by the host communication device 4, in which a particular message is sent to each member 6 of the communication group. In one example, the broadcast message may be used to issue an update to a safety procedure, and may be sent by a station manager (host) to the engineering staff associated with that station (members). As the information is transmitted directly to the relevant staff, this enables information to be shared significantly more effectively than traditional alternatives such as posting the information on a noticeboard. The broadcast message is not particular limited in format, and could for example include document format data, allowing documents to be directly messaged to the relevant users so that messages can be transmitted in an appropriate format. The broadcast message can also be used to issue time critical information, such as emergency announcements, to the relevant groups of users.

[0052] Figure 4 schematically illustrates a member message issued by a member communication device 6 to the host communication device 4. In one example, the member message could be used to report information to the host communication device, which can for example allow a member of staff to report information to a responsible manager. For example, a potential hazard could be reported to a manager who can take appropriate action, and which can move the responsibility from the member of staff to the responsible manager.

[0053] Hence, as shown in Figures 3 and 4 the communication system may provide asymmetric messaging in which a host communication device may transmit certain messages to several member communication devices, but where the member communication devices may transmit messages individually to the host communication device alone.

[0054] In some examples, as discussed in greater detail below, messages sent between the host and member communication devices may request an acknowledgement indicating that those messages have been understood by the recipient, which can provide guarantees on the flow of information via such a communication system.

[0055] Figure 5 schematically illustrates a communication system comprising a plurality of communication devices and communication channels between the plurality of communication devices. Figure 5 illustrates a communication system in which the plurality of communication devices are associated with privilege levels. Each communication device has been provided a label in the format XY, with X illustrating a privilege level of that communication device and Y distinguishing the communication devices at a given privilege level. In the example of Figure 5, lower values of X indicate higher privilege levels.

[0056] The use of privilege levels is one approach which may be used to control whether a given device is permitted to act as a host device 4 to establish a communication group comprising a particular communication device as a member. A device may be permitted to establish a communication group comprising devices at a lower privilege level than itself, but not comprising devices at the same or a higher privilege level than itself. The use of privilege levels can enable a hierarchical communication system to be established in which the communication devices at a given privilege level have the ability to decide which devices at lower privilege levels they would like to communicate with, and hence groups can be established downwards in privilege (although within a group messages may be transferred both upwards and downwards in privilege). It is the choice of the operator of the communication system which privilege levels to assign to particular communication devices. In some examples, privilege levels could for example be chosen to correspond to levels of seniority within an organisation. Returning to the previous example, in a railway the highest privilege level may be assigned to the communication device of the most senior manager, a lower privilege level for less senior managers such as a station manager or train manager, and a lower privilege level still for their staff (train staff, station staff, etc.). In some examples, members of staff at the same level within an organisation but in different teams (e.g., station staff and train staff) could be at the same privilege level or at different privilege levels depending on whether communication between those teams should be permitted. Figure 5 illustrates arrows originating at host communication devices and indicating members of communication groups established by those host communication devices. It will be seen that in Figure 5 each host device establishes communication groups with lower privilege member communication devices. For example, the device labelled 00 establishes communication groups comprising the devices labelled 10, 11 , and 12.

[0057] Two communication channels are illustrated between device 00 and device 11 , as communication device 11 may be a member of two separate communication groups established by device 00 (e.g., a first group comprising devices 10 and 11 and a second group comprising devices 11 and 12), although it will be appreciated that in practice there may only exist a single link between devices 00 and 11 used for messages of both communication groups.

[0058] Device 10 is illustrated establishing a communication group comprising devices at privilege level 2 (devices 20 and 21) and at privilege level 3 (device 31), and hence it will be appreciated that a communication device is not restricted to establish a communication group only with the devices at a neighbouring privilege level. In the railway example given above, this may for example mean that communication groups can be provided comprising a senior manager and a station manager, as well as a group comprising the senior manager and engineering staff (which may or may not include the station manager).

[0059] Figure 5 illustrates that a communication device (e.g., device 21) may be a member of a plurality of communication groups established by different host communication devices (e.g., device 21 is a member of communication groups established by devices 10 and 11).

[0060] Figure 5 illustrates that communication devices may act as both a host device and a member device in different communication groups. For example, device 10 is a member of a communication group hosted by device 00 and is also a host of a communication group comprising devices 20, 21 , and 31.

[0061] In some examples, a host communication device 4 may be configured to establish a communication group comprising a single member communication device 6. For example, Figure 5 may show device 11 establishing two communication groups, one comprising devices 21 and 22 and one comprising only device 23.

[0062] Within the communication system illustrated in Figure 5, the only routes via which messages may be transferred may be the routes illustrated by arrows. Messages may be transmitted both ways on these routes, from the host to the member and from the member to the host. However, messages may not be transmitted via other routes. Therefore, devices at a given privilege level may not be permitted to communicate with each other via the communication system. For example, the communication devices of station staff may be assigned to privilege level 2 and hence the station staff may be unable to communicate with each other via the communication system (but may nevertheless be able to communicate with the station manager at a higher privilege level if that station manager has established a communication group comprising those station staff), hence reducing the likelihood for the communication system to be a source of distraction, and reducing a volume of messages transferred via the communication system.

[0063] Figure 6 is a ladder diagram illustrating a host communication device 4 transmitting a key message to a target member communication device 6. The key message requests an acknowledgement from the target member communication device. The acknowledgement may be issued in response to a user input from the user of the target member communication device, and hence can indicate that the message has been actively acknowledged. Such acknowledgements could for example be used to transfer a burden of responsibility within an organisation. For instance, once a user has acknowledged a message identifying a particular hazard, then a burden of responsibility may be shifted from the sender of the message to the receiver of the message for handling the hazard appropriately. Similarly, if the station manager sends a key message including an update to a safety procedure and the message is acknowledged by a member of station staff, then this acknowledgement may be used to indicate that the member of station staff is responsible for adhering to the updated safety procedure.

[0064] In some examples, a member communication device may be configured to send a key message to a host communication device requesting an acknowledgement from the host communication device.

[0065] As illustrated in Figure 6, a host communication device 4 may issue a key message to a member communication device 6 (or, in some cases, the member 6 may issue a key message to a host 4). Receipt of the message may be communicated to the user of the receiving device who may provide an input (e.g., opening the message) to cause the message to be presented to the user (e.g., displayed on a screen, or played through a speaker) at step 602.

[0066] Presentation of the key message to the user at step 602 may start a delay period. For example, this may cause a clock to begin counting the delay period. At step 604, a user input is received to acknowledge the key message. For example, if the communication device has a screen for displaying the message the user input could involve pressing a button displayed on the screen, although it will be appreciated that in general any user input may be used for this purpose. However, the user input 604 is received during the delay period and hence does not cause an acknowledgement message to be issued to the host communication device 4. By enforcing a delay period, the risk of accidental acknowledgement of the key message may be reduced. The delay period may also be used to reduce the chance of messages being dismissed before their contents can be understood. Hence, the delay period can increase the level of trust that may be placed on the acknowledgement indicating that the contents of the key message has been understood.

[0067] At step 606 a further user input is received. The user input 606 is received after expiry of the delay period (e.g., the clock started at step 602 has reached a value equal to or greater than the length of the delay), and hence causes the acknowledgement to be issued. Therefore, at step 608 the acknowledgement message is transmitted from the member communication device 6 to the host communication device 4.

[0068] Figure 7 schematically illustrates an example communication device 4, 6, 8 which may be employed within a communication system discussed herein. Figure 7 illustrates the communication device comprising storage circuitry 700, a transmitter / receiver 702, a display controller 704, input circuitry 706, processing circuitry 708, and geolocation circuitry 710, although it will be appreciated that in some examples not all of these elements may be required and in some examples further elements may be provided.

[0069] The storage circuitry 700 enables data to be stored by the communication device, and may for example include random access memory (RAM), which may be provided as part of a system on a chip (SoC). Further storage may be provided by a disk, either as an external or internal hard drive, or as an external solid state drive, or an internal solid state drive.

[0070] The transmitter / receiver 702 enables data to be transmitted from and received at the communication device. Data may be transmitted or received via a wired or wireless network, such as via a mobile network. In some examples, data may be received via one or more data ports, such as a universal serial bus (USB) port, Ethernet® port, Wi-Fi® port, Bluetooth® port, as appropriate. In particular, the transmitter / receiver 702 may enable data to be transmitted to and received from message routing circuitry 2, which can provide a path via which messages may be transferred between separate communication devices.

[0071] The display controller 704 controls the presentation of information to a user. The display controller may for example control transmission of data via one or more audio / visual (A / V) outputs. The display controller may for example control display of information on a screen visible to a user and / or transmission of audio data from a speaker.

[0072] The input circuitry 706 enables information to be provided to the communication device from a user. For example, the input circuitry may comprise one or more of a touchscreen (which may be the same screen controlled by the display controller 704 for displaying information), a mouse, a keyboard, and so on.

[0073] The processing circuitry 708 may comprise, for example, a central processing unit (CPU) and optionally a graphical processing unit (GPU), which may be integrated with the RAM in the SoC. The processing circuitry may execute software comprising instructions and data stored within the storage circuitry 700, and may control one or more of the other elements of the communication device.

[0074] Geolocation circuitry 710 may be configured to determine a location of the communication device, such as by determining the co-ordinates of the communication device. The geolocation circuitry may for example use a satellite navigation system, a Wi-Fi positioning system, and so on to determine the location of the communication device.

[0075] The processing circuitry 708 may be configured to execute software including a communication application providing access to a communication system. The software may for example control the transmitter / receiver 702 to communicate with message routing circuitry 2 to enable messages to be transmitted to other communication devices in the communication system. In some examples, access to the communication application may require a user to enter identifying information (such as a password or biometric information) via the input circuitry 706 to provide a guarantee of the identify of a user of a particular communication device.

[0076] In some examples, a given communication device may require an invite from a communication device within the communication system before the given communication device is permitted to send or receive messages via the message routing circuitry within the communication system. For example, the given communication device may be prohibited from sending / receiving messages within the communication system until the given communication device has received an invite which may comprise verification information. The verification information may in some examples include a one-time password (OTP) and / or may include verification information to be included in messages sent by the given communication device. Hence, in some examples, even having access to the communication application does not permit a user to access the communication system unless the invite has been received.

[0077] Interaction with the communication system may be via a user interface displayed to the user via the display controller 704 and which takes inputs via the input circuitry 706. The user interface may for example display identities of other communication devices to which the communication device may transmit messages (and allow the contents of those messages to be generated), and may enable the communication device to establish communication groups with certain communication devices. The user interface may also display messages received from other communication devices in the communication system to the user, and may allow the user to provide an input to acknowledge certain key messages. In some examples, the appearance of the user interface may be determined by settings in the communication application which may vary between operators of different communication systems. In this way, the same back end can be used to provide communication systems which appear in different ways to the user, although which may function in similar ways. Different operators may also select different settings for the communication system (e.g., whether or not a delay is required for key messages and if so the delay length, the format of privilege information controlling the establishing of communication groups, and so on).

[0078] Via the user interface, a user is able to access a communication system as illustrated for example in Figure 5, in which the user may be permitted to send messages within established communication groups but not otherwise, and may be permitted to establish communication groups with a limited group of other communication devices.

[0079] Communication devices within the communication system may be identified in various ways. In some examples, communication devices may be identified by one or more of: a mobile number, a name of a user of the communication device, and an identifying number associated with the user of the communication device. In some examples, the storage circuitry 700 may provide data indicating privilege levels associated with other communication devices in the system, and this information may be used to control, at a particular communication device, the establishing of communication groups by that communication device. In other examples, the communication device may issue requests to communication devices requesting that they join a communication group hosted by that device, the requests including privilege information associated with the prospective host device, and the prospective member communication devices may perform a comparison between the privilege information associated with the prospective host device and their own privilege information to determine whether they are permitted to join the group and respond accordingly.

[0080] The storage circuitry 700 may also maintain a record of existing communication groups comprising the communication device, where this record may be consulted to determine whether the communication device is permitted to transmit a message to a particular other communication device, and also control which devices should receive broadcast messages issued by the communication device.

[0081] In some examples, the transmitter / receiver circuitry 702 is configured to transmit geolocation information determined by the geolocation circuitry 710 to one or more host communication devices which are identified in the storage circuitry 700 as having established communication groups comprising the communication device. The geolocation information may be transmitted at regular intervals, or for example each time the communication device transmits a message to the host communication device.

[0082] Figure 8 schematically illustrates an example of message routing circuitry 2 which may be employed within a communication system discussed herein. The message routing circuitry may comprise storage circuitry 800, transmit / receive circuitry 802, and processing circuitry 804.

[0083] The storage circuitry 800 enables data to be stored by the message routing circuitry, and may for example include random access memory (RAM), which may be provided as part of a system on a chip (SoC). Further storage may be provided by a disk, either as an external or internal hard drive, or as an external solid state drive, or an internal solid state drive.

[0084] The transmitter / receiver 802 enables data to be transmitted from and received by the message routing circuitry. Data may be transmitted or received via a wired or wireless network, such as via a mobile network. In some examples, data may be received via one or more data ports, such as a universal serial bus (USB) port, Ethernet® port, Wi-Fi® port, Bluetooth® port, as appropriate. In particular, the transmitter / receiver 802 may enable data to be received from a communication device and transmitted to a further communication device, providing a path for messages to be transferred between separate communication devices.

[0085] The processing circuitry 804 may comprise, for example, a central processing unit (CPU) and optionally a graphical processing unit (GPU). The processing circuitry may execute software comprising instructions and data stored within the storage circuitry 800, and may control one or more of the other elements of the message routing circuitry. Hence, the message routing circuitry 2 can enable messages to be transferred between communication devices. In some examples, messages may be received by the message routing circuitry 2 identifying a target communication device and the message routing circuitry may transmit the message to the target communication device without performing any checks, relying on each communication device (and the communication application) to prevent messages from being transmitted other than via permitted communication channels. In other examples, the message routing circuitry 2 may store an indication of permitted message communication channels and may prohibit transferring messages outside these channels.

[0086] The storage circuitry 800 may in some examples maintain a record of messages transferred between communication devices. For example, an indication of the sender and receiver, time of sending, time of acknowledgement, and content of message could be tracked. This information can provide a compliance record in safety critical applications. For example, if the compliance record identifies that a message has been transmitted from a member of station staff to the station manager identifying a hazard, and that message has been acknowledged, then this can be used to prove that responsibility for the hazard was with the station manager. Similarly, if the compliance record indicates that a safety update was transmitted to a member of staff and acknowledged, then this could be used to show that the member of staff had acknowledged responsibility for following the updated safety procedure and that failure to do so may lie with the member of staff.

[0087] Figure 9 is a flow diagram illustrating a method of using a communication system. At step 900, a host communication device 4 establishes a communication group comprising one or more member communication devices. At step 902, message routing circuitry 2 routes messages between the host communication device and the member communication devices within the communication group. At step 904, the communication devices prohibit transfer of messages other than via communication channels established by a host communication device.

[0088] Figure 10 is a flow diagram illustrating a method of transmitting a key message via a communication system, in particular where a host communication device issues a key message to a member communication device within a communication group. The method illustrated in Figure 10 corresponds to the process illustrated in Figure 6. At step 1000 a host communication device issues the key message to one or more target member communication devices. At step 1002 the message routing circuitry 2 causes the key messages to be transferred to the one or more target member communication devices.

[0089] At step 1004 the key message is presented to a user of a target member communication device, and a counter begins counting a delay period.

[0090] At step 1006 a user input is received, and at step 1008 it is determined whether the delay period has expired. If not (e.g., the counter started at step 1004 has not yet reached a threshold), then at step 1010 no acknowledgement is issued in response to the user input received at step 1006. However, if the delay has expired then at step 1012 an acknowledgement is issued to the host communication device in response to the user input received at step 1006.

[0091] In the present application, the words “configured to...” are used to mean that an element of an apparatus has a configuration able to carry out the defined operation. In this context, a “configuration” means an arrangement or manner of interconnection of hardware or software. For example, the apparatus may have dedicated hardware which provides the defined operation, or a processor or other processing device may be programmed to perform the function. “Configured to” does not imply that the apparatus element needs to be changed in any way in order to provide the defined operation.

[0092] In the present application, lists of features preceded with the phrase “at least one of’ mean that any one or more of those features can be provided either individually or in combination. For example, “at least one of: [A], [B] and [C]” encompasses any of the following options: A alone (without B or C), B alone (without A or C), C alone (without A or B), A and B in combination (without C), A and C in combination (without B), B and C in combination (without A), or A, B and C in combination.

[0093] Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS1. A communication system, comprising a plurality of communication devices comprising one or more host communication devices; wherein a given host communication device is configured to establish a plurality of communication channels to transfer messages via message routing circuitry between the given host communication device and a plurality of member communication devices forming a communication group of the plurality of communication devices; and the plurality of communication devices are prohibited from transferring messages via the message routing circuitry other than via a communication channel established by the one or more host communication devices.

2. The communication system according to claim 1 , wherein the plurality of communication channels established by the given host communication device do not permit messages to be transferred between the plurality of member communication devices of the communication group.

3. The communication system according to any preceding claim, wherein the plurality of communication devices provide a safety critical communication system for transferring safety critical messages.

4. The communication system according to any preceding claim, wherein the given host communication device is configured to issue a broadcast message to the plurality of member communication devices of the communication group.

5. The communication system according to any preceding claim, wherein a given member communication device is configured to issue a member message to the host communication device.

6. The communication system according to any preceding claim, wherein the plurality of communication devices are each associated with privilege information, and a prospective host communication device is configured to perform a comparison of host privilege information associated with the prospective host communication device and member privilege information associated with a given member communication device to determine whether the prospective host communication device is permitted to establish a communication group comprising the given member communication device.

7. The communication system according to claim 6, wherein the privilege information comprises an indication of a device privilege level, and a given communication device is prohibitedfrom establishing a communication group comprising member communication devices having a higher device privilege level than themselves.

8. The communication system according to any preceding claim, wherein the message routing circuitry comprises history storage circuitry configured to maintain a message record of messages transferred within the communication group.

9. The communication system according to any preceding claim, wherein a given communication device is configured to issue a key message to one or more target member communication devices in the communication group, the key message requesting an acknowledgement from the one or more target member communication devices.

10. The communication system according to claim 9, wherein a given target member communication device is configured to issue the acknowledgement in response to an acknowledgement input from a user.

11. The communication system according to claim 10, wherein the given target member communication device is configured to suppress issuing the acknowledgement in response to an acknowledgement input from a user provided before expiry of a delay period following presentation of the key message to the user.

12. The communication system according to any preceding claim, wherein the given host communication device is configured to permit removal of one or more member communication devices from the communication group.

13. The communication system according to any preceding claim, wherein the plurality of member communication devices in the communication group are configured to transmit geolocation information to the given host communication device.

14. The communication system according to any preceding claim, wherein the message routing circuitry is configured to transfer messages using a mobile network.

15. The communication system according to any preceding claim, wherein plurality of communication devices comprise at least one mobile device.

16. The communication system according to any preceding claim, wherein the message comprises at least one of: text, image, video, audio, and document data.

17. The communication system according to any preceding claim, wherein the given host communication device is a member communication device for a further communication group.

18. The communication system according to any preceding claim, wherein the given host communication device is configured to establish two or more independent communication groups.

19. A communication device configured exchange messages with one or more further communication devices via message routing circuitry; wherein the communication device is configured to establish a plurality of communication channels to transfer messages via message routing circuitry between the communication device and a plurality of member communication devices forming a communication group of the one or more further communication devices; and the communication device is prohibited from transferring messages via the message routing circuitry other than via a communication channel established by a host communication device.

20. A communication method, comprising: providing a plurality of communication devices comprising one or more host communication devices; establishing a plurality of communication channels to transfer messages via message routing circuitry between the given host communication device and a plurality of member communication devices forming a communication group of the plurality of communication devices; and prohibiting transfer of messages between the plurality of communication devices other than via communication channels established by the one or more host communication devices.

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