WO2016114695A1

WO2016114695A1 - Interference management in multiple technology environment

Info

Publication number: WO2016114695A1
Application number: PCT/SE2015/050033
Authority: WO
Inventors: Johan Torsner; Anna Larmo; Leif Wilhelmsson
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2015-01-15
Filing date: 2015-01-15
Publication date: 2016-07-21

Abstract

A wireless communications node is capable of connecting to different technology networks. The node determines that at least one first node is operating in a first technology network,and that at least one second node is operating in at least one respective second technology network, wherein the first technology network and the second technology network are different. The node determines information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network, and transmits a signalling message containing said information to at least one device using the first technology network.

Description

INTERFERENCE MANAGEMENT IN MULTIPLE TECHNOLOGY

ENVIRONMENT

TECHNICAL FIELD This invention relates to wireless communications, and in particular to communications in an environment in which multiple technologies are in use.

BACKGROUND There exist multiple wireless communications technologies, by which devices can communicate with each other. Several of these technologies are relatively short range radio communications technologies, operating according to their standards in

unlicensed frequency bands. In particular, several of these operate in the 2.4 GHz Industrial, Scientific and Medical (ISM) radio frequency band. Examples of such standards are Bluetooth, Zigbee, certain IEEE 802.11 standards, WirelessHART etc. These different systems typically use different channel bandwidths and channel spacings. However, because these technologies operate in the same frequency band, this means that the communication using one technology can be subject to interference from devices using other technologies.

In order to co-exist well with other technologies that also use the same band,

communication systems in the ISM band must typically deploy some co-existence scheme. One common co-existence mechanism is frequency hopping, whereby communication between two devices switches rapidly between frequency channels, making the communication robust against interference and frequency dependent fading. Frequency hopping is used in Bluetooth, Bluetooth Low Energy (BLE) and WirelessHART, for example, in order to make the communication robust against interference by other systems, such as a Wi-Fi system deployed in the same building. In BLE, for example, adaptive frequency hopping is used, whereby the devices estimate the quality on each communication channel and only perform the frequency hopping on the channels that are free from interference. Another co-existence method used, for example, in Zigbee is dynamic channel selection (or frequency agility) whereby the devices scan the available channels during connection setup and select a channel with no or little interference for communication. If that channel becomes interfered during the communication, the devices may search for a better channel and switch to that. Co-existence methods such as frequency hopping and dynamic frequency selection work fairly well when there is little traffic and interference in an area. When the interference and data traffic increases, however, they tend to perform poorly, leading to packet collisions, longer delays and low throughput.

One reason for this is that it is difficult to accurately perform the channel classification, that is, the process where a device determines from measurements if a channel is suitable for communication or not. Different measurements can be used e.g. receiver signal strength indication (RSSI), SNR or packet/block error rate measurements.

Packet/block error rate measurements are simple to perform but they take a relatively long time to perform since a number of packets need to be received before the packet error rate can be determined accurately. If a channel is unnecessarily classified as unreliable it means that a suitable communication resource is not used. This may cause reduced throughput and increased delay as a consequence. On the other hand, if an interfered channel is classified as usable it means that it will be subject to interference with packet losses as a consequence, also leading to reduced throughput and increased delays. Mechanisms to make the channel classification faster and more reliable are therefore important.

For many existing deployments of short range systems such as Bluetooth, BLE or WirelessHART, the most likely interferer is a Wi-Fi system deployed in the same area. The document "Adaptive Frequency Hopping for Bluetooth Robust to WLAN

Interference", Seung-Hwang Lee et al, IEEE Communications Letters, vol 13, No. 9, September 2009, proposes an adaptive frequency hopping scheme, in which Bluetooth channels are divided into groups, where one group contains the Bluetooth channels that could be interfered by W-Fi transmission on a certain W-Fi channel. The idea is that the channel classification can be done per channel group instead of per individual channel, and reduce the time taken to perform the classification.

This system is however unable to deal with all interference scenarios. Although Wi-Fi (IEEE 802.11) is a common interferer, it is likely that future scenarios will consist of a mix of different technologies. It is not possible to know before a new system is deployed which other system or systems will interfere with the communications in the new system. During its use, the new system may suffer interference from a system that may not even have been invented when the new system was designed and deployed. It is therefore not possible to take account in advance of the interference that will be present. Thus, the prior art scheme discussed above has the difficulty that it is not practically possible a priori to divide the channels into appropriate groups. There is also an issue with performing channel characterizations in cases where the amount of data to be sent is very small, say only a few bytes. One example where short packets may be transmitted relatively seldom could be a sensor network, where a few bytes of sensor data are sent once a day. This means that, whereas the actual data transfer may only take on the order of 100με, it may take 1-10 seconds to classify the channels. Especially if these small data transfers occur relatively seldom, it means that the channel classification needs to be redone for every transmission, which is relatively inefficient.

SUM MARY

According to an aspect of the invention, there is provided a method for use in a wireless communications node capable of connecting to different technology networks. The method comprises: determining that at least one first node is operating in a first technology network, determining that at least one second node is operating in at least one respective second technology network, wherein the first technology network and the second technology network are different, determining information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network, and

transmitting a signalling message containing said information to at least one device using the first technology network.

Transmitting the signalling message may comprise broadcasting the signalling message to all devices using the first technology network within range of the gateway node.

The signalling message may comprise information relating to which of a plurality of frequency channels on the first technology network can potentially be interfered with when a transmission takes places on one of a plurality of frequency channels of one of the at least one second technology network, and/or information relating to the load on at least on frequency channel of one of the plurality of second technology networks which may potentially interfere with devices operating on the first technology network.

The first and at least one second technologies may be short range radio access technologies.

According to a second aspect of the invention, there is provided a node for use with at least two different technology networks. The node comprises means for determining that at least one first node is operating in a first technology network, means for determining that at least one second node is operating in at least one respective second technology network, wherein the first technology network and the second technology network are different, and a processing module for determining information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network, and for sending said information to at least one device in said first technology network.

According to a third aspect of the invention, there is provided a method for use in a device operating in a first technology network. The method comprises receiving signals from a node capable of connecting to first and second technology networks, said signals containing information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network; and operating in the first technology network based on said information. The method may comprise adapting transmission parameters for use by said device based on said information. Adapting the transmission parameters may comprise selecting channels for use by said device based on said information, or selecting a modulation scheme for use by said device based on said information, or selecting a coding for use by said device based on said information, or selecting a transmitter power for use by said device based on said information.

According to a fourth aspect of the invention, there is provided a device, for use in a first technology network. The device comprises a communications module for receiving signals from a node capable of connecting to first and second technology networks, said signals containing information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network; and a processing module for using said information in controlling operation of the device in the first technology network.

There is therefore provided a system for speeding up, and improving the accuracy of, the classification of usable and unusable channels in adaptive frequency hopping schemes, dynamic frequency allocation schemes, and the like. This can allow a reduced packet error rate and reduced delays for communication.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a communications environment. Figure 2 is a block diagram illustrating a first node in the environment of Figure 1.

Figure 3 is a block diagram illustrating a communications device in the environment of Figure 1. Figure 4 is a block diagram illustrating a second node in the environment of Figure 1. Figure 5 is a first channel map illustrating a first radio environment. Figure 6 is a second channel map illustrating a second radio environment.

Figure 7 is a flow chart, illustrating a method in accordance with one embodiment.

Figure 8 is a flow chart, illustrating a method in accordance with one embodiment.

DETAILED DESCRIPTION

Figure 1 illustrates a communications environment, containing devices that are capable of communicating according to different communications standards. Specifically, Figure 1 shows a communications environment in which multiple devices are able to communicate using the 2.4 GHz Industrial, Scientific and Medical (ISM) radio frequency band, although it will be appreciated that the methods and devices described herein could equally be applied to communications in other frequency bands.

Figure 1 shows devices 10, 12, 14, 16, 18 that are able to communicate using a wireless communications standard A, a device 20 that is able to communicate using a wireless communications standard B, devices 22, 24 that are able to communicate using a wireless communications standard C, and devices 26, 28, 30, 32 that are able to communicate using a wireless communications standard D.

Figure 1 also shows a node 40 that is able to communicate using all four of the wireless communications standards A, B, C and D. The wireless communications standards A, B, C and D may be selected from a group of standards that operate in a common frequency band, in this example the 2.4 GHz ISM radio frequency band, such as Bluetooth, Bluetooth Low Energy (BLE), Zigbee, certain IEEE 802.1 1 standards, and WirelessHART, as examples.

This group of standards include standards such as Bluetooth that are primarily intended for short-range point-to-point communications between two devices that are located in close proximity to each other.

Thus, for example, in the situation illustrated in Figure 1 , the devices 10 and 12 might be able to communicate with each other using the wireless communications standard A, while the devices 26 and 28 might be able to communicate with each other using the wireless communications standard D.

In one embodiment, the node 40 also acts as a gateway node, for example an access point in a Wireless Local Area Network (WLAN) using a suitable IEEE 802.11 standard. Thus, for example, the device 20 might able to communicate with other devices using that wireless communications standard, with traffic passing through the node 40. As another example, the node 40 might be a gateway node providing an interworking function between different short range communication systems. Thus, a device that uses one wireless communications standard is able to communicate with a device that uses a different wireless communications standard by sending data via the node 40, which reads the data in the standard used by the transmitting device and retransmits the data in the standard used by the receiving device.

However, the functions of the node 40, as described herein, can also be performed by other nodes that are not gateway nodes.

As shown in Figure 1 , two of the devices, namely devices 16 and 28, are able to act as relay devices where necessary, as described in more detail below. Thus, the device 16 is able to act as a relay between the device 14 and the node 40, while the device 28 is able to act as a relay between the device 26 and the node 40.

The devices 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, and 32, including the relay devices 26 and 28, and the node 40 are all referred to generally herein as nodes where required.

Figure 2 shows the general form of the node 40.

The node 40 includes a communications module 42 and a data processing and control unit 44. The communications module is configured for communicating over a wireless interface according to the wireless communications standards A, B, C and D. Thus, the communications module 42 generates signals in a suitable form for transmission in accordance with the relevant communications standard and also receives signals that have been transmitted in accordance with a suitable communications standard, and extracts data from the received signals. In the case where the node 40 is a gateway node such as a WLAN access point, the communications module is also configured for communicating over a wide area network, for example the internet.

The data processing and control unit includes a processor 46 and a memory 48. The processor 46 performs data processing and logical operations, and the memory 48 may contain working data, and may also contain stored instructions for causing the processor 46 to perform the methods described below.

Figure 3 shows the general form of the device 10, and it will be noted that the other devices have a generally similar form. The device 10 includes a communications module 52 and a data processing and control unit 54. The communications module is configured for communicating over a wireless interface according to one or more of the wireless communications standards A, B, C and D. Thus, the communications module 52 generates signals in a suitable form for transmission in accordance with the relevant communications standard and also receives signals that have been transmitted in accordance with a suitable communications standard, and extracts data from the received signals.

The data processing and control unit includes a processor 56 and a memory 58. The processor 56 performs data processing and logical operations, and the memory 58 may contain working data, and may also contain stored instructions for causing the processor 56 to perform the methods described below.

Figure 4 shows the general form of the relay device 16, and it will be noted that the other relay devices have a generally similar form.

The relay device 16 includes a communications module 62 and a data processing and control unit 64. The communications module is configured for communicating over a wireless interface according to one or more of the wireless communications standards A, B, C and D. Thus, the communications module 62 generates signals in a suitable form for transmission in accordance with the relevant communications standard and also receives signals that have been transmitted in accordance with a suitable communications standard, and extracts data from the received signals. Where appropriate, the communications module 62 is also able simply to forward signals that it has received from the node 40 to one of the devices, and vice versa, in accordance with the relevant communications standard.

The data processing and control unit includes a processor 66 and a memory 68. The processor 66 performs data processing and logical operations, and the memory 68 may contain working data, and may also contain stored instructions for causing the processor 66 to perform the methods described below.

Figure 5 is a first diagram, illustrating one possible radio environment in the communications environment shown in Figure 1. Thus, Figure 5 shows the channel map for the Bluetooth Low Energy (BLE) technology. (Thus, BLE defines 40 channels in the 2.4 GHz band numbered 0 through 39. The distance between two adjacent channels is 2 MHz, and the bandwidth of each channel is about 1 MHz so that very little signal power leaks in to adjacent channels. Classical Bluetooth uses a different arrangement, defining 79 channels with 1 MHz spacings.)

Three of the BLE channels (numbers 37, 38 and 39) are used as advertising channels and the remaining 37 channels are data channels. When data is transmitted, the transmission cycles through the 37 data channels according to a pseudo random algorithm that is known in both the transmitter and the receiver.

Figure 5 also shows, superimposed on the BLE channels, three W-Fi channels.

Specifically, Figure 5 shows channels 1 , 6 and 1 1 in a system as defined in IEEE 802.1 1 b (channels 1 , 6 and 11 being commonly used in such systems).

Figure 6 is a second diagram, illustrating another possible radio environment in the communications environment shown in Figure 1.

Thus, Figure 6 shows the channel map for the Zigbee technology (using the IEEE 802.15.4 physical layer). Zigbee uses 2 MHz wide channels with a 5 MHz channel spacing.

Figure 6 also shows three 22 MHz wide Wi-Fi channels as defined in IEEE 802.11 b, namely channels 1 , 7 and 13.

Figures 5 and 6 therefore illustrate the potential for interference between the different communications technologies. A Wi-Fi access point operating in the 2.4 GHz band will typically occupy a bandwidth of approximately 22 MHz. This means that, if a Wi-Fi access point is installed in the same area as two devices that are attempting to communicate using BLE, around 10 consecutive BLE channels will be interfered by the Wi-Fi transmission. Similarly, if a Wi-Fi access point is installed in the same area as two devices that are attempting to communicate using Zigbee, around 4 Zigbee channels will be interfered. Figure 7 is a flow chart, illustrating a method performed in one wireless

communications node, while Figure 8 is a flow chart, illustrating a method performed in another wireless communications node. The method shown in Figure 7 is performed in a device such as the node 40 shown in Figure 1 , namely a node that supports at least two different communication

technologies, and is therefore capable of receiving signals in at least two different communications networks. The communication technologies may be short range radio technologies operating in an unlicensed band and using some co-existence scheme, such as adaptive frequency hopping or dynamic frequency selection. To perform the co-existence scheme some or all of the devices performs estimations of the channel quality of the available communication channels, based on measurements of BLER, SNR, PER, or similar. As mentioned in connection with Figure 1 , the node 40 may act as a gateway node in one of the communication technologies, but this is not necessarily the case.

In the method shown in Figure 7, in step 72, the node 40 receives signals from at least one first node operating in a first technology network. By way of illustration only, referring to the environment shown in Figure 1 , the node 40 may be able to detect signals transmitted by the devices 10, 12, 14, 16, 18 that are able to communicate using the wireless communications technology A. This allows the node 40 to determine that there is at least one node operating in this technology network. Also, in this illustrated example, in step 74, the node 40 receives signals from at least one second node operating in a second technology network. By way of illustration only, referring to the environment shown in Figure 1 , the node 40 may be able to detect signals transmitted by the device 20 that is able to communicate using the wireless communications technology B.

The signals detected by the node 40 might be traffic signals that can be detected by the node 40. Alternatively, the signals detected by the node 40 might be channel allocation signals. In either case, the signals allow the node 40 to determine which channels in the second technology network are in actual or planned use. The traffic signals transmitted and received by the node 40 itself might be the signals in the wireless communications technology B that will potentially interfere with the wireless communications technology A. Thus, the node 40 is able to make this determination based on knowledge of the channels that it is using.

Based on these detected signals, or the other information known to the node 40, in step 76, the node 40 determines information relating to the potential interference that may be experienced by devices 10, 12, 14, 16, 18 operating on the first technology network due to the at least one second technology network.

Then, in step 78, the node 40 transmits a signalling message containing said information to at least one device using the first technology network.

The information determined by the node 40, and included in the signaling message, can, for example, describe which channels in the first technology network can potentially be interfered when transmission on a certain channel in a second technology network system B occurs. For example, if Wi-Fi transmission is performed on channel 6, BLE channels 11 through 20 may be interfered, as can be seen from Figure 5. This information can be transferred as a bitmap, channel list, or similar.

As another example, the information determined by the node 40, and included in the signaling message, can describe the load of the channels that potentially may interfere with the first technology network.

As an illustration of this, if the interfering system (i.e. the second technology network) is Wi-Fi using Channel 6, and this is the only interference, the first technology network (for example, BLE) may simply avoid the corresponding channels. However, it could be that case that Channel 1 and Channel 11 are also being used by other W-Fi systems. If these three channels are all occupied, it is beneficial to know how much traffic there is on the different channels. If, for example, Channel 1 and Channel 1 1 are almost fully occupied, whereas Channel 6 is only in use for a small fraction of the time, it may still be useful to allow the BLE system to operate on the frequencies that potentially may be interfered by Channel 6. The "load", as indicated in the signaling message, may for example mean the percentage of the time that a channel is expected to be used, the number of users that are using the channel, or what kind of traffic there is, amongst other possibilities. The node 40 may then transmit a signalling message in step 78 if two or more systems supported by the node can potentially interfere with each other. The signalling message transmitted in step 78 may be sent using the first communications technology itself.

The signalling message transmitted in step 78 may for example be transmitted as a broadcast message that can be detected by other devices that may not necessarily be connected to the node 40. Such a broadcast message may for instance be transmitted at regular intervals, say once every second.

As an alternative, the signaling message transmitted in step 78 may be transmitted only when transmission on one system is about to begin, for example when data is available for transmission. As another alternative, the signaling message transmitted in step 78 may be transmitted only when the load in one or more of the systems exceeds a threshold level.

It is mentioned above that the node 40 can transmit to the devices operating on the first technology network information relating to the interference that those devices may suffer, because of transmissions taking place in the second technology network. It should also be noted that the node 40 can also transmit to the devices operating on the second technology network information relating to the interference that those devices may suffer, because of transmissions taking place in the first technology network.

The method shown in Figure 8 is performed in a device such as the device 10 shown in Figure 1 , which is a device that is able to communicate using the wireless

communications technology A in the description of Figure 7. In the method shown in Figure 8, in step 82, the device 10 receives the signalling message transmitted by the node 40, containing information relating to the interference that may be caused by devices using the second technology network. By way of illustration only, in this example, the device 10 is operating using BLE, while the signalling message transmitted by the node 40 contains information relating to the interference that may be caused by devices using Wi-Fi. In step 84, the device 10 acts on the received signalling message by adapting its transmission parameters. For example, the device 10 may set the channels that it uses, the used modulation, or the used coding, the transmitter power level or a combination of such transmission parameters.

In one embodiment of the invention, the device or devices that have received the signaling message use the information to assist in the channel classification. In the illustrated example, if the node 40 indicates that Wi-Fi channel 6 is in use, potentially interfering with BLE channels 1 1 - 20, the BLE device 10 can treat the channels 1 1 - 20 as one set, and can perform BLER or PER measurements relating to all data transmitted or received on those channels, instead of doing that estimation for each channel separately.

In another embodiment of the invention, the device or devices that have received the signaling message do not perform any measurements, but simply refrain from using those channels that are indicated as being potentially interfered.

In yet another embodiment of the invention, the device or devices that have received the signaling message use the information to assist in the channel classification. For example, a device may perform measurements on the channels that are indicated as being potentially interfered, but give those channels lower priority when selecting channels, for example by applying a threshold so that the potentially interfered channels need to be better than other free channels by a certain margin in order for them to be used for communication.

In yet another embodiment of the invention, the device or devices makes use of more than one received signaling message and combines the information in order to perform the channel classification. In yet another embodiment of the invention, the device which receives the information does not process it but merely forward it to the device it is connected to. One situation when this would be applicable would be if a Bluetooth device that has taken the slave role, and therefore is not in charge of the frequency selection, receives the information from a Wi-Fi access point and then without further processing forward this information to the master of the Bluetooth connection. Thus, in the situation illustrated in Figure 1 , the node 40 may be a Wi-Fi access point that is also able to detect signals transmitted by Bluetooth devices 10, 12, 14, 16, 18, but the Bluetooth device 14 is out of range of the node 40, while the Bluetooth device 16 is taking the slave role in communications with the device 14. In this case, the device 16 receives the signaling message transmitted by the node 40 in step 78, and simply forwards it to the master Bluetooth device 16, which can take account of the contents thereof when setting its transmission parameters.

The node may transmit a signaling message that is to be used for a long period or for a short period.

For example, in the case of a node 40 in the form of a Wi-Fi access point, the node 40 will know which Wi-Fi channel it will be using, and therefore which channels will potentially be interfered in other technologies. Therefore, it can send a signaling message to devices such as BLE devices, indicating which BLE channels will be interfered by the Wi-Fi transmission on the configured W-Fi channel, and possibly indicating that these channels should not be used for transmission. Since the node 40 has this information, it can transmit this information even before the Wi-Fi transmission starts, allowing the BLE devices to avoid the relevant channels.

Alternatively, if data is being transmitted only intermittently to or from a node 40 in the form of a Wi-Fi access point, the interference from the Wi-Fi transmissions will also be intermittent. In this case, the node 40 can consider the actual traffic transmissions. When Wi-Fi data transmission is about to begin, or the Wi-Fi access point receives signaling from a connected Wi-Fi device that indicates that another Wi-Fi device is about to begin data transmission, it can then classify the corresponding BLE channels as "bad". It will then send a signaling message to the connected BLE devices that the corresponding BLE channels should be avoided. Conversely, when the Wi-Fi transmission or reception stops, the access point can signal to the BLE devices that the corresponding BLE channels are usable again.

Thus, a node that is able to use several radio technologies can optimize the frequency hopping pattern for one technology based on information about which other technologies are installed, their configuration and the traffic pattern on them. There are therefore disclosed methods and devices for operating in a wireless communications environment for potentially providing reduced interference and increased communication efficiency for communications devices. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim, "a" or "an" does not exclude a plurality, and a single feature or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

1. A method for use in a wireless communications node capable of connecting to different technology networks comprising:

determining that at least one first node is operating in a first technology network, determining that at least one second node is operating in at least one respective second technology network, wherein the first technology network and the second technology network are different,

determining information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network, and

2. A method as claimed in claim 1 wherein the at least one device using the first technology network is the first node.

3. A method as claimed in claim 1 or 2 wherein the step of transmitting comprises broadcasting the signalling message to all devices using the first technology network within range of the gateway node.

4. A method as claimed in any preceding claim, wherein

the signalling message is only sent when a transmission on one of the technology networks is about to begin.

5. A method as claimed in one of claims 1-3, wherein

the signalling message is transmitted only when the load in one or more of the technology networks exceeds a threshold value.

6. A method as claimed in any of the preceding claims wherein

the signalling message comprises information relating to which of a plurality of frequency channels on the first technology network can potentially be interfered with when a transmission takes places on one of a plurality of frequency channels of one of the at least one second technology network.

7. A method as claimed in any of the preceding claims wherein, the signalling message comprises information relating to the load on at least on frequency channel of one of the plurality of second technology networks which may potentially interfere with devices operating on the first technology network.

8. A method as claimed in any of the preceding claims wherein the first and at least one second technologies are short range radio access technologies.

9. A node for use with at least two different technology networks, the node being configured for:

determining that at least one first node is operating in a first technology network, determining that at least one second node is operating in at least one respective second technology network, wherein the first technology network and the second technology network are different, and

determining information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network, and for sending said information to at least one device in said first technology network.

10. A node as claimed in claim 9 wherein the at least one device using the first technology network is the first node.

1 1. A node as claimed in claim 9 or 10 wherein the processing module is configured for broadcasting the signalling message to all devices using the first technology network within range of the gateway node.

12. A node as claimed in any of claims 9 to 11 , wherein

said information is only sent when a transmission on one of the technology networks is about to begin.

13. A node as claimed in one of claims 9 to 1 1 , wherein

said information is transmitted only when the load in one or more of the technology networks exceeds a threshold value.

14. A node as claimed in any of claims 9 to 13 wherein

said information comprises information relating to which of a plurality of frequency channels on the first technology network can potentially be interfered with when a transmission takes places on one of a plurality of frequency channels of one of the at least one second technology network.

15. A node as claimed in any of claims 9 to 13 wherein

said information comprises information relating to the load on at least on frequency channel of one of the plurality of second technology networks which may potentially interfere with devices operating on the first technology network.

16. A node as claimed in any of claims 9 to 15 wherein the first and at least one second technologies are short range radio access technologies.

17. A method for use in a device operating in a first technology network, comprising: receiving signals from a node capable of connecting to first and second technology networks, said signals containing information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network; and

operating in the first technology network based on said information.

18. A method as claimed in claim 17, comprising adapting transmission parameters for use by said device based on said information.

19. A method as claimed in claim 18, wherein adapting the transmission parameters comprises selecting channels for use by said device based on said information.

20. A method as claimed in claim 18, wherein adapting the transmission parameters comprises selecting a modulation scheme for use by said device based on said information.

21. A method as claimed in claim 18, wherein adapting the transmission parameters comprises selecting a coding for use by said device based on said information.

22. A method as claimed in claim 18, wherein adapting the transmission parameters comprises selecting a transmitter power for use by said device based on said information.

23. A device, for use in a first technology network comprising: a communications module for receiving signals from a node capable of connecting to first and second technology networks, said signals containing information relating to the potential interference that may be experienced by devices operating on the first technology network due to the at least one second technology network; and a processing module for using said information in controlling operation of the device in the first technology network.

24. A device as claimed in claim 23, wherein the processing module is configured to adapt transmission parameters for use by said device based on said information.

25. A device as claimed in claim 24, wherein adapting the transmission parameters comprises selecting channels for use by said device based on said information.

26. A device as claimed in claim 24, wherein adapting the transmission parameters comprises selecting a modulation scheme for use by said device based on said information.

27. A device as claimed in claim 24, wherein adapting the transmission parameters comprises selecting a coding for use by said device based on said information.

28. A device as claimed in claim 24, wherein adapting the transmission parameters comprises selecting a transmitter power for use by said device based on said information.