WO2001084870A1

WO2001084870A1 - Wireless communication system and method

Info

Publication number: WO2001084870A1
Application number: PCT/EP2001/005086
Authority: WO
Inventors: Shaun Richard Fenton; Christopher Frank Phillips; Christopher Warren Wright; Andrew John Aftelak; Philip Alan Tottle
Original assignee: Motorola Inc.
Priority date: 2000-05-03
Filing date: 2001-05-03
Publication date: 2001-11-08
Also published as: AU766859B2; AU6740801A; CN1428060A; GB0010598D0; EP1281287A1; GB2362069A

Abstract

A system for, and method of, optimising communication on one or more wireless communications systems, wherein a transmission procedure is determined in accordance with information about the environment in which a mobile station (MS) wishing to transmit is located. The mobile station may gain information about the environment by communication with other mobile stations (MS). The present invention provides methods and systems for choosing the most suitable channel or access method for making a transmission from a mobile station.

Description

Wireless Communication System and Method

Field of the Invention

This invention relates to wireless communications systems. More specifically, this invention relates to the optimisation of communication on such systems.

Background of the Invention

Wireless communications systems typically comprise a number of radios, which may be linked together in a variety of ways. These 'radios' may be mobile 'phones. They may alternatively be mobile or portable radios, usually referred to as 'PMR' radios. The term mobile station (MS) will be used henceforth for mobile telephones and portable- or mobile radios.

The mobile stations may communicate through base stations of the system. Each base station typically serves a cell of the wireless communications system. The base stations offer interconnection either to the fixed line telephone system ('POTS'), or to other mobile stations in the system. Mobiles that communicate through base stations may or may not be in the same cell of the network. Alternatively, mobile stations may communicate directly with one another, in 'direct mode' communication.

In currently operating wireless communications systems which incorporate an infrastructure managing the network, mobile stations within that network receive a multitude of information from the base station controller (BSC). This information assists them in making optimal use of the radio channels available within the network. However, the case for networks with no managing infrastructure, termed ad-hoc networks, is very different. Devices within such systems are only able to obtain such information by analysing their environment, i.e. the radio and usage conditions of all the available channels in their area of current operation. This analysis is very time consuming and, as such, is undesirable from a system performance point of view. Similarly, in some instances, mobile stations within a network managed by an infrastructure will not receive enough information from the base station controller (BSC) to enable them to make optimal use of the channels available for use in the network.

In view of this, there exists a problem in that the mobile stations (MSs) within a wireless communications system are unable to optimise their communication and performance by utilising the most appropriate radio channel to communicate upon. This problem exists particularly in ad-hoc systems, but also for systems utilising a managing infrastructure.

The problem already outlined with reference to optimising channel selection extends to the use of mobile communications devices which are able to access more than one wireless access system. Examples of such wireless access systems are global system for mobile communications (GSM) systems, universal mobile telecommunications systems (UMTS) and Bluetooth systems. In the situation where the capabilities of these systems overlap, there exists a problem in that a device capable of accessing more than one system in a given location is unable to optimise its communication and performance by utilising the most suitable access method and/or system.

The present invention addresses some or all of the above disadvantages.

Summary of the Invention

The present invention provides a method of, and system for, optimising communication on one or more wireless communications systems. In accordance with the invention, a transmission procedure is determined in accordance with information about the environment in which a mobile station (MS) wishing to transmit is located.

According to a preferred embodiment of the present invention, there is provided a method wherein determining the transmission procedure may comprise choosing either a wireless channel or an access method to be utilised in the required transmission. The information about the environment may include radio conditions and channel/system usage information. The information may be gleaned from other mobile stations within an area surrounding the mobile station wishing to transmit. Alternatively, the information may be obtained via a network or a number of networks in which area of coverage the MS is located. Further, the information may be shared amongst the MSs within a network. Such sharing may be achieved by way of Peer Assist Message (PAM) signalling packets broadcast by one or more MSs and received by all MSs within a specific range.

MSs within a network may monitor the PAM packets and, when transmission is required, determine therefrom which channel should be used to transmit upon.

When an MS tunes to a new wireless channel, the following steps may be carried out. The MS may monitor and analyse the PAM signalling packets being broadcast by MSs in its vicinity, it may identify information which will complement the information already carried by the PAM packets present in the network, and it may broadcast a PAM signalling packet containing the information identified. Complementary information may comprise information not being broadcast amongst the MSs in the network, and information which is being broadcast by an MS which is geographically distant from the newly tuned MS and is not being relayed by an MS in the vicinity thereof. Geographical distance may be determined using global positioning system (GPS) information, or bit error rate (BER) and signal strength.

The information shared between MSs may further include current channel status, alternative channel activity and information relating to MS locations. The channel most suited for transmission may be determined in accordance with these pieces of information. Additionally, MS location information may be utilised to form peer routing maps for the MSs in a network. Such maps could assist MSs in transmitting packets of data (via chains of peer MSs) to other MSs which would otherwise be out of range of the originating device. Further, alliterative channel activity may be utilised to enable an MS to join a call on an alternative channel to which it is partied.

In a further preferred embodiment, an MS wishing to make a transmission may send a request for information to nearby mobile stations, it may receive and evaluate responses to that request, it may choose a most suitable access method, or methods, for transmission and it may connect to an appropriate system or appropriate systems. Nearby mobile stations may be defined as being those devices with which a mobile station can communicate via a direct mode radio channel. Additionally, a request for information may include a request for MS locations and routing maps. The supply of this information may enable the MS making the request to build up and share address book information.

Requests for information may include requests for a current load on a system, a cost of access to a system, current quality of service parameters associated with a system, and battery life. The decision of whether to join a system, made by an MS, is based upon a set of criteria. If those criteria are met by a system, that system may be considered to be suitable by the MS.

In a further preferred embodiment, an MS may send a request for information to a number of networks within whose area of coverage it is located, it may receive and evaluate the responses from all networks to which the request was sent, it may choose the most suitable access method or methods for transmission, and may connect to one or more appropriate systems. Once again, the request for information may include requests for a current load on a system, a cost of access to a system, current quality of service parameters associated with the system, and battery life. The decision whether or not to join a system may be based upon a set of criteria. If these criteria are met by a system, that system may be considered suitable by the MS.

There is also provided a system for optimising communication on one or more wireless communications systems, wherein a transmission procedure is determined in accordance with information about the environment in which a mobile station (MS) wishing to transmit is located.

Brief Description of the Figures

Additional specific advantages of the present invention will be apparent from the following description and figures in which:

Figure 1 shows a number of mobile stations within an area of coverage of a network;

Figure 2 shows a mobile station and a number of signals associated therewith;

Figure 3 shows a flow diagram illustrating the behaviour of an MS upon its being tuned to a new channel in an ad-hoc communications network;

Figure 4 depicts mobile stations situated in the area of coverage of several networks; and

Figure 5 shows a flow diagram detailing a method of determining which network or networks are most suited for transmission.

Figure 6 illustrates the general scheme of a wireless communications system 10 in accordance with the present invention.

Figure 7 illustrates a mobile station (MS) in accordance with the present invention.

The present invention is now described with reference to the accompanying drawings, as detailed above. Description of Preferred Embodiments

As may be seen in Figure 1 , in a network situation, whether it is an ad-hoc network or a cellular communications network utilising a governing infrastructure, there are a number of mobile stations (MSs) 102, 106 within the area of coverage 104 of the network. In an ad-hoc network, there exists at least one radio channel for use in communication and a number of MSs, known as peers, which may communicate over that channel with one another. No single entity is in overall control of the network; each MS must have its own set of access rules. These rules determine the MS's behaviour.

Figure 2 details the way in which mobile stations share information with one another. As may be observed, an MS 202 may broadcast a peer assist message (PAM) 204 signalling packet. A PAM packet may be broadcast regularly by any device on a channel which has no call in progress, or it may be embedded within a communication which is currently taking place on a channel, by one or more of the devices involved in that communication. Mobile stations use the information contained in incoming PAM packets 206 to optimise their own use of the channels available. In addition, mobile stations which broadcast PAM signalling packets also utilise the incoming information contained in incoming packets to optimise the information they provide in their own PAM packets.

Examples of information transmitted as a part of a PAM signalling packet, and how that information may be utilised by the MSs which receive it, may be seen below:

1) Channel Identifier - this piece of information identifies the channel currently being used by the MS broadcasting the PAM signalling packet. Such a signal may be utilised by scanning mobile stations to aid them in the location and prioritising of potential radio channels. As such, this information is of use in the grouping together, into particular channels, of mobile stations seeking to set up communications with one another. 2) Channel Status - this piece of information indicates what is occurring on the channel currently associated with the MS broadcasting the PAM packet at any given time. It may consist of an indication that no call, a standard call, an emergency call or a packet data transfer is in progress.

3) Network Parameters - this piece of information generally contains miscellaneous network parameters such as "random access frame length" and "maximum call duration". Optimal values for these parameters may be calculated by specific mobile stations and propagated to other mobile stations for their use.

4) New Arrivals - this piece of information announces the presence of new arrivals on the current channel. Such information may be employed in the dynamic update of MS address books within the network.

5) Radio Location - this piece of information announces the location of specific radios either in terms of the channel number to which they are tuned, or in terms of an ad-hoc network routing map. The network routing map is a map detailing how each device may be communicated with by all other devices in the network, i.e. which intermediary devices must be utilised to achieve the desired range of communication. This could also be used to dynamically update MS address books.

6) Alternate Channel Activity - this piece of information indicates what is occurring on other channels. Such information may be used to indicate the absence or presence of a call on an alternative channel to which an MS in the current channel is partied.

MSs within a network learn about the environment (i.e. the radio conditions, usage conditions and user information) in one of two ways. The first of these is a passive method in which the MS monitors activity upon the channel which it is currently configured to utilise, and processes the information contained in any incoming PAM packets. The second method is an active method, wherein the MS "pings" other MSs within the system requesting from them specific information such as "radio location".

Figure 3 depicts the action taken by an MS when it joins a network. In this case, the network is an ad-hoc network, but the same may be true for a network managed by an infrastructure. When an MS which is required to broadcast its own PAM packets tunes to a new channel, it spends some time monitoring and analysing the PAM signalling packets already being broadcast on that channel (function box 302). The MS then identifies what information should be included within its own PAM signalling packet in order to best complement the information present, rather than to duplicate it (function box 304). The MS may also choose to relay the contents of PAM packet broadcasts originating at distant MSs in an attempt to maximise the area of coverage of the shared information. Information already being relayed by a nearby MS would not be relayed by the newly tuned MS in this fashion.

For example, where PAM signalling packets describing the channel activity on a number of alternative channels, 1 to 3, within a network are being broadcast by another MS in the immediate vicinity, the MS joining a network may choose to broadcast information relating to a further three alternative channels, 4 to 6. However, where PAM signalling packets describing the channel activity on channels 1 to 3 are already being broadcast by a distant MS, then in addition to broadcasting the channel activity on channels 4 to 6, the newly joined MS may also choose to relay the channel activity on channels 1 to 3. Such a choice would ensure that the information relating to channels 1 to 3 is broadcast throughout the broadcast range of the newly tuned MS.

The final step to be taken, as set forth in function box 306, is that of the MS beginning to broadcast its chosen information. This broadcast is carried out in either of the ways already discussed.

In order to make the decision whether or not information should be relayed, it is necessary for an MS to be able to determine the geographical distance between itself and the MS whose broadcast it is considering relaying. Any viable method of determining this distance may be employed. However, two ways, the use of which are contemplated, are described below.

The first geographical distance evaluation method consists of including in each PAM packet a global positioning system (GPS) location of the MS broadcasting that packet, or attaching such an indication of location to the packet in some way. The receiving MS would then calculate the distance from that GPS location and its own GPS location. A GPS receiver would be necessary for this evaluation method to operate correctly. Such a receiver may be either a component part of an MS, or may be an add on accessory.

The second method consists of the receiving MS calculating the distance from the quality of reception of the received PAM signalling packet. This quality may be quantified by the bit error rate (BER) and signal strength.

It is clear from the above that the sharing of information in this way removes the necessity for each MS in an ad-hoc communications network to analyse all characteristics of its environment. As such, sharing information between peers facilitates the selection of the best channel to transmit upon. For example, in an exemplary six channel ad-hoc network containing three broadcast channels and three receive channels, if an MS desires to transmit a message on the current channel to which it is currently tuned, but that channel is busy, the shared information may indicate that an alternative channel is free and may be used. Thus the MS may transmit on the alternative channel rather than waiting for the current channel to become free, and then possibly colliding with a further MS also wishing to transmit on that channel, which may necessitate a further wait. The most suitable channel to use may be determined using an algorithm which utilises any appropriate weighted combination of one or more pieces of the information gleaned from surrounding MSs or from the network infrastructure. Additionally, the construction of address books and peer routing maps enables transmission from an MS to a further MS, which is outside the broadcast range of the first MS, via intermediate MS(s). The construction of such books and maps is dependent upon the sharing of information.

Figure 4 illustrates the case where more than one network 404, 406, 408, whether ad-hoc or infrastructure managed, is present surrounding the location of a particular MS 402. In such a scenario, it is important that the MS wishing to make a transmission is able to determine which access system (and/ or associated network) is best suited to the making of that transmission. There are two methods of determining which access method or network should be utilised. The first involves the interrogation of nearby mobile stations and is described, with reference to Figure 5, below.

When a mobile station 402 that has the capability to connect to more than one wireless communications system is located within a geographical area 404, 406, 408 covered by more than one such system, and desires to make a transmission which is suited to more than one such system and access scheme, the device 402 must make a choice. The choice comprises of deciding which of the present access schemes should be used, and is made based upon a set of criteria. The criteria will be largely implementation dependent, but may include "current load on system", "cost of access", "current quality of service parameters", and "battery life" etc.

In order to make the choice, the MS sends a request for information to nearby MSs 410 (function box 502). The request is a request for information and is sent to MSs which currently have calls established with the relevant systems. The request is transmitted on one or more suitable channels, which may comprise a channel common to all the systems in the vicinity, or a suitable channel defined within each system. The nearby devices then respond with the requested information in a suitable return channel (function box 504).

Communication between the various MSs, as detailed with reference to function boxes 502 and 504, is by way of direct communication between mobile stations on a direct mode radio channel, i.e. direct MS to MS communication. This does not need to involve network infrastructure in any way, but could do if appropriate.

Based upon the information returned to it by the nearby MSs 410, the MS 402 wishing to transmit must choose the most suitable access method or methods (function box 506). Such a choice is carried out by determining which of the available methods satisfy the relevant criteria, and selecting them. The final step is to connect to the chosen network or networks via the chosen access method or methods (function box 508).

As mentioned before, the criteria upon which such decisions are made are implementation dependent. However, the area in which MSs are considered nearby is defined by the maximum transmission range of the MS making the request for information. All MSs within that range are considered nearby.

In order for this procedure to operate, all MSs are required to make available the criteria upon which decisions are based. This may be provided for by the standardisation of the time division duplex (TDD) mode for third generation partnership project (3GPP) systems. The new standards should include opportunity division multiple access (ODMA) technology wherein this procedure is applicable. As an example, the relay path to a base station may be established by the interrogation of neighbouring devices for quality of service information. The MS requesting information would then make a decision on which relay path to use based upon this information.

The second possible method of determining which access method/network should be utilised for the making of a transmission is generally the same as that described above with reference to Figure 5. The main difference is that instead of interrogating the nearby mobile stations, the request for information is sent to the networks in the vicinity. The networks gather the requested information from the data streams of nearby devices in communication therewith and return it to the device that made the request. It follows that the data streams must therefore contain location information, an identifier of the access system, and embedded data relating to the quality of service that the associated device is currently experiencing.

The form of the request sent in this method is implementation dependent. It may be a request directed to a centralised intelligence with access to information on data streams carried on each of the access systems. Alternatively, it may be directed to an intelligent agent, within each system or within each system's area of coverage, which is able to gather the requested information itself.

An advantage of the second method is that it eliminates potentially lengthy direct mode radio communications (i.e. MS to MS) which consume power and spectrum, therefore making the MS equipment more complex. However, the level of complexity is far greater than for the first method.

Both of these methods provide the advantage of enabling a suitable MS to establish and utilise the access method that provides optimal communication conditions. This may be determined by the best quality of service, lowest cost etc. or a combination of criteria, and allows communication to be optimised in ways not presently possible.

Whilst the above methods have been described generally with reference to ad-hoc systems, it will be clear to the reader that they apply equally to communications systems which utilise a managing infrastructure. It will be equally appreciated that apparatus able to carry out the above methods is included within the scope of the invention. A description of such apparatus is described below.

Figure 6 illustrates the general scheme of one example of a wireless communications system 10 in accordance with the present invention. Mobile stations 2, 4 and 6 of figure 6 can communicate with a base station 8. Mobile stations 2, 4 and 6 could be mobile telephones. Alternatively, they could be PMR radios, i.e. portable radios or mobile radios mounted in vehicles. Each of the mobile stations shown in figure 6 can communicate through base station 8 with one or more other mobile stations. If mobile stations 2, 4 and 6 are capable of direct mode operation, then they may communicate directly with one another or with other mobile stations, without the communication link passing through base station 8.

Figure 7 illustrates a mobile station (MS) in accordance with the present invention. The mobile station (MS) of figure 7 is a radio communication device, and may be either a portable- or a mobile radio, or a mobile telephone.

The mobile station 2 of figure 7 can transmit speech from a user of the mobile station. The mobile station comprises a microphone 34 which provides a signal for transmission by the mobile station. The signal from the microphone is transmitted by transmission circuit 22. Transmission circuit 22 transmits via switch 24 and antenna 26.

Mobile station 2 also has a controller 20 and a read only memory (ROM) 32. Controller 20 may be a microprocessor.

ROM 32 is a permanent memory, and may be a non-volatile Electrically Erasable Programmable Read Only Memory (EEPROM). ROM 32 is connected to controller 20 via line 30.

The mobile station 2 of figure 7 also comprises a display 42 and keypad 44, which serve as part of the user interface circuitry of the mobile station. At least the keypad 44 portion of the user interface circuitry is activatable by the user. Voice activation of the mobile station may also be employed. Similarly, other means of interaction with a user may be used, such as for example a touch sensitive screen.

Signals received by the mobile station are routed by the switch to receiving circuitry 28. From there, the received signals are routed to controller 20 and audio processing circuitry 38. A loudspeaker 40 is connected to audio circuit 38. Loudspeaker 40 forms a further part of the user interface. A data terminal 36 may be provided. Terminal 36 would provide a signal comprising data for transmission by transmitter circuit 22, switch 24 and antenna 26. Data received by receiving circuitry 28 may also be provided to terminal 36. The connection to enable this has been omitted from figure 7 for clarity of illustration.

It will be understood that this invention has been described above by way of example only, and that modifications of detail may be made within the scope of this invention.

Claims

1. A method of optimising communication on one or more wireless communications systems, characterised in that a transmission procedure is determined in accordance with information about the environment in which a mobile station (MS) wishing to transmit is located.

2. A method as claimed in claim 1 , wherein determining the transmission procedure comprises choosing either a wireless/radio channel or an access method for the transmission.

3. A method as claimed in either preceding claim, wherein the information about the environment includes radio conditions, and channel/system usage information.

4. A method as claimed in any preceding claim, wherein the information is gleaned from other MSs within an area surrounding the mobile station.

5. A method as claimed in any preceding claim, wherein the information is obtained via a network or networks in whose area of coverage the MS is located.

6. A method as claimed in any preceding claim, wherein the information is shared amongst MSs within a network.

7. A method as claimed in any preceding claim, wherein the information is shared by way of Peer Assist Message (PAM) signalling packets, broadcast by one or more MSs and received by all MSs within a specific range thereof.

8. A method as claimed in claim 7, wherein an MS monitors the PAM packets and, when it wishes to transmit, determines which of a number of possible channels should be used.

9. A method as claimed in claim 8, wherein the channel to be used is determined using an algorithm which utilises any weighted combination of a single piece, or some or all pieces of the information gleaned from surrounding MSs or the network infrastructure.

10. A method as claimed in any preceding claim, wherein, upon tuning to a new wireless channel, an MS with PAM broadcast capability carries out the steps of:

monitoring and analysing (302) PAM signalling packets being broadcast by MSs in it's vicinity;

identifying (304) information that complements the information carried by the PAM packets already being broadcast; and

broadcasting (306) a PAM signalling packet containing the information identified.

11. A method as claimed in claim 10, wherein complementary information comprises information not being broadcast amongst the MSs, and information which is being broadcast by an MS distant geographically from the newly tuned MS and which is not being relayed by an MS in the vicinity thereof.

12. A method as claimed in claim 11 , wherein geographical distance is determined using global positioning system (GPS) information, or bit error rate (BER) and signal strength.

13. A method as claimed in any preceding claim, wherein the information includes current channel status, alternative channel activity and information relating to MS location.

14. A method as claimed in claim 13, wherein a channel most suited for transmission is chosen in accordance with the status and activity of all available channels within the network.

15. A method as claimed in any preceding claim, comprising the steps of the MS:

sending (502) a request for information to nearby mobile stations;

receiving (504) and evaluating responses to the request;

choosing (506) a most suitable access method or methods for transmission; and

connecting (508) to an appropriate system or appropriate systems.

16. A method as claimed in claim 15, wherein nearby devices are defined by devices which may be communicated with via a direct mode radio channel.

17. A method as claimed in either of claims 15 or 16, wherein the request for information may include a request for a current load on a system, a cost of access to a system, current quality of service parameters associated with a system, and battery life.

18. A method as claimed in any of claims 15 to 17, wherein the decision of whether to join a system is based upon a set of criteria, and if these criteria are met by a system, that system is considered suitable by the MS.

19. A method as claimed in any preceding claim, comprising the steps of the MS:

sending a request for information to networks within whose area of coverage it is located;

receiving and evaluating the network responses;

choosing a most suitable access method or methods for transmission; and

connecting to an appropriate system or systems.

20. A method as claimed in claim 19, wherein the request for information may include a request for a current load on a system, a cost of access to a system, current quality of service parameters associated with a system, and battery life.

21. A method as claimed in claim 20, wherein the network obtains the information from the data streams of nearby mobile stations in communication therewith.

22. A method as claimed in any of claims 19 to 21 , wherein the decision of whether to join a system is based upon a set of criteria, and if these criteria are met by a system, that system is considered suitable by the MS.

23. A system utilising the method of any of claims 1 to 22.

24. A system for optimising communication on one or more wireless communications systems, wherein a transmission procedure is determined in accordance with information about the environment in which a mobile station (MS) wishing to transmit is located.