GB2471299A

GB2471299A - Delegation of radio channel reservation

Info

Publication number: GB2471299A
Application number: GB0910909A
Authority: GB
Inventors: Markus Nentwig
Original assignee: Nokia Oyj
Current assignee: Nokia Oyj
Priority date: 2009-06-24
Filing date: 2009-06-24
Publication date: 2010-12-29
Anticipated expiration: 2029-06-24
Also published as: GB0910909D0; WO2010150115A1; GB2471299B

Abstract

A first apparatus is configured to control a transmitter to broadcast at least one reservation signal, which may be a beacon, for reserving a radio channel and to control the transmitter to transmit at least one message to a further apparatus. A second apparatus is configured, in response to receipt of the at least one message from the first apparatus, to assume responsibility from the first apparatus for broadcasting at least one reservation signal 510 and control a transmitter to broadcast at least one reservation signal 520. The first apparatus may receive a reply message confirming responsibility for broadcasting the reservation signals has been transferred and cease controlling the transmitter to broadcast reservation signals. The reservation signals may reserve the right to undisturbed reception or transmission on a radio channel. An apparatus is further configured to, in response to receipt of at least one message from another apparatus, determine that a radio channel is available for broadcasting at least one reservation signal.

Description

TITLE

Radio channel allocation

FIELD

Exemplary embodiments of the present invention relate to radio channel allocation. In particular, they relate to mitigating interference by flexibly allocating radio channels to networks.

BACKGROUND

A first radio device may transmit a radio signal to a second radio device on a radio channel. If a third radio device, located close to the second radio device, also attempts to use the same radio channel to transmit a radio signal to a fourth radio device, it may cause interference at the second radio device.

BRIEF DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

According to various, but not necessarily all, embodiments of the invention there is provided an apparatus configured to control a transmitter to broadcast at least one reservation signal for reserving a radio channel, and configured to control the transmitter to transmit at least one message to a further apparatus, enabling transfer of responsibility, from the apparatus to the further apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

The apparatus may be configured, in response to responsibility for broadcasting at least one reservation signal being transferred from the apparatus to the further apparatus, to cease controlling the transmitter to broadcast reservation signals.

The apparatus may be configured to determine, from receipt of a reply message from the further apparatus, that responsibility for broadcasting reservation signals for reserving a radio channel has been transferred to the further apparatus.

The apparatus may be configured to transmit the at least one message to the further apparatus after a wireless communication link has been established, on a radio channel, between the apparatus and the further apparatus.

The at least one reservation signal may be for reserving a right to undisturbed reception on a radio channel, or for reserving a right to transmit on a radio channel. The reservation signals may be beacons.

According to various, but not necessarily all, embodiments of the invention there is provided an electronic device comprising a transmitter and an apparatus as described above.

According to various, but not necessarily all, embodiments of the invention there is provided a method, comprising: controlling a transmitter to transmit at least one message from an apparatus to a further apparatus, enabling transfer of responsibility, from the apparatus to the further apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

The method may further comprise: ceasing to control the transmitter to broadcast reservation signals, in response to responsibility for broadcasting at least one reservation signal being transferred from the apparatus to the further apparatus.

The method may further comprise: determining, from receipt of a reply message from the further apparatus, that responsibility for broadcasting at least one reservation signal for reserving a radio channel has been transferred to the further apparatus.

The at least one message may be transmitted to the further apparatus after a wireless communication link has been established, on a radio channel, between the apparatus and the further apparatus.

The at least one reservation signal may be for reserving a right to undisturbed reception on the radio channel, or for reserving a right to transmit on at least one radio channel.

According to various, but not necessarily all, embodiments of the invention there is provided a computer program comprising computer program instructions that, when executed by a processor, enable: controlling a transmitter to transmit at least one message from an apparatus to a further apparatus, enabling transfer of responsibility, from the apparatus to the further apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

The computer program instructions may further enable: ceasing to control the transmitter to broadcast reservation signals, in response to responsibility for broadcasting at least one reservation signal being transferred from the apparatus to the further apparatus.

The computer program instructions may further enable: determining, from receipt of a reply message from the further apparatus, that responsibility for broadcasting at least one reservation signal for reserving a radio channel has been transferred to the further apparatus.

The at least one reservation signal may be for reserving a right to undisturbed reception on the radio channel.

According to various, but not necessarily all, embodiments of the invention there is provided an apparatus configured, in response to receipt of at least one message from another apparatus, to assume responsibility, from the another apparatus, for broadcasting at least one reservation signal for reserving a radio channel, and the apparatus being configured to control a transmitter to broadcast at least one reservation signal for reserving a radio channel.

The apparatus may be configured to assume responsibility for broadcasting at least one reservation signal for reserving a radio channel, after determining that at least one condition has been fulfilled.

The apparatus may be configured to analyze a radio signal from the another apparatus to determine that the at least one condition has been fulfilled. The apparatus may be configured to analyze the radio signal by determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

The apparatus may be configured, prior to broadcasting at least one reservation signal for reserving a radio channel, to determine that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel.

The apparatus may be configured to determine that a radio channel is available for broadcasting at least one reservation signal by controlling a receiver to scan for reservation signals.

According to various, but not necessarily all, embodiments of the invention there is provided a method, comprising: assuming responsibility from an apparatus, in response to receipt of at least one message from the apparatus, for broadcasting at least one reservation signal for reserving a radio channel; and controlling a transmitter to broadcast at least one reservation signal for reserving a radio channel.

It may be that responsibility for broadcasting at least one reservation signal for reserving a radio channel is assumed, after determining that at least one 1 0 condition has been fulfilled.

The method may further comprise: analyzing a radio signal from the another apparatus to determine that the at least one condition has been fulfilled.

Analyzing the radio signal may include determining at least one of: a received 1 5 signal strength, a phase, and a time of flight of the radio signal.

The method may further comprise: determining, prior to broadcasting at least one reservation signal for reserving a radio channel, that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel.

Determining that a radio channel is available for broadcasting at least one reservation signal may comprise controlling a receiver to scan for reservation signals.

According to various, but not necessarily all, embodiments of the invention there is provided a computer program comprising computer program instructions that, when executed by a processor, enable: assuming responsibility from an apparatus, in response to receipt of at least one message from the apparatus, for broadcasting at least one reservation signal for reserving a radio channel; and controlling a transmitter to broadcast at least one reservation signal for reserving a radio channel.

It may be that responsibility for broadcasting at least one reservation signal for reserving a radio channel is assumed, after determining that at least one condition has been fulfilled.

The computer program instructions may further enable: analyzing a radio signal from the another apparatus to determine that the at least one condition has been fulfilled. Analyzing the radio signal may include determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

The computer program instructions may further enable: determining, prior to broadcasting at least one reservation signal for reserving a radio channel, that a radio channel is available for broadcasting at least one reservation signal for 1 5 reserving a radio channel.

According to various, but not necessarily all, embodiments of the invention there is provided an apparatus configured, in response to receipt of at least one message from another apparatus, to determine that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel, and the apparatus being configured, in response to determining that a radio channel is available for broadcasting the at least one reservation signal, to control a transmitter to broadcast at least one reservation signal for reserving a radio channel.

The apparatus may be configured, in response to receipt of the at least one message from another apparatus, to assume responsibility, from the another apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

The apparatus may be configured to assume responsibility for broadcasting at least one reservation signal for reserving a radio channel, after determining that at least one condition has been fulfilled. The apparatus may be 1 0 configured to analyze a radio signal from the another apparatus, in order to determine that the at least one condition has been fulfilled.

The apparatus may be configured to analyze the radio signal by determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

According to various, but not necessarily all, embodiments of the invention there is provided an electronic device comprising a transmitter and the apparatus as described above.

According to various, but not necessarily all, embodiments of the invention there is provided a method, comprising: determining, in response to receipt of at least one message, that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel; and controlling, in response to determining that a radio channel is available for broadcasting the at least one reservation signal, a transmitter to broadcast at least one reservation signal for reserving a radio channel.

The method may further comprise: in response to receipt of the at least one message from the apparatus, assuming responsibility from the apparatus for broadcasting at least one reservation signal for reserving a radio channel.

A radio signal from the apparatus may be analyzed, in order to determine that 1 0 the at least one condition has been fulfilled. Analyzing the radio signal may include determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

According to various, but not necessarily all, embodiments of the invention there is provided a computer program comprising computer program instructions that, when executed by a processor, enable: determining, in response to receipt of at least one message, that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel; and controlling, in response to determining that a radio channel is available for broadcasting the at least one reservation signal, a transmitter to broadcast at least one reservation signal for reserving a radio channel.

The computer program instructions may further enable: in response to receipt of the at least one message from the apparatus, assuming responsibility from the apparatus for broadcasting at least one reservation signal for reserving a radio channel.

A radio signal from the apparatus may be analyzed, in order to determine that the at least one condition has been fulfilled. Analyzing the radio signal may include determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

Each of the apparatuses described above may be processing circuitry.

Each of the reservation signals described above may be beacons.

According to various, but not necessarily all, embodiments of the invention there is provided at least one computer program that, when executed by a processor, enables at least one of the methods described above to be performed.

According to various, but not necessarily all, embodiments of the invention there is provided at least one tangible computer readable medium storing at least one of the computer programs described above.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of various examples of embodiments of the present invention reference will now be made by way of example only to the accompanying drawings in which: Fig. 1 illustrates an exemplary first apparatus; Fig. 2 illustrates another exemplary apparatus; Fig. 3 illustrates exemplary a further apparatus; Figs. 4A, 4B and 40 illustrate exemplary first, second, third and fourth apparatuses in different scenarios.

Fig. 5A illustrates a first exemplary method; Fig. 5B illustrates a second exemplary method; and Figs 6A, 6B and 6C illustrate an exemplary network comprising first and second apparatuses, where the first and second apparatuses are in close proximity.

DETAILED DESCRIPTION

The Figures illustrate an exemplary apparatus 1 0/1 00/110/200/21 0 configured 1 0 to control a transmitter 1 6/11 6/21 6 to broadcast at least one reservation signal 128/130 for reserving a radio channel, and configured to control the transmitter 16/116/216 to transmit at least one message 126 to a further apparatus 200/1 00, enabling transfer of responsibility, from the apparatus 1 0/100/11 0/200/21 0 to the further apparatus 200/21 0, for broadcasting at 1 5 least one reservation signal 1 28/1 30 for reserving a radio channel.

The Figures also illustrate an exemplary apparatus 10/100/110/200/210 configured, in response to receipt of at least one message 126 from another apparatus 200/100, to assume responsibility, from the another apparatus 200/100, for broadcasting at least one reservation signal 128/130 for reserving a radio channel, and the apparatus 10/100/110/200/210 being configured to control a transmitter 16/116/216 to broadcast at least one reservation signal 1 28/1 30 for reserving a radio channel.

Fig. 1 illustrates an exemplary apparatus 10. The apparatus 10 may, for example, be a controller in the form of processing circuitry. Implementation of the processing circuitry may be in hardware alone (a circuit, a processor or the like), have certain aspects in software including firmware alone or may be a combination of hardware and software (including firmware).

The apparatus 1 0 is configured to control a transmitter 1 6. The transmitter 1 6 may, for example, be a transmitter that is configured to transmit radio frequency signals. For instance, the transmitter 16 may be configured to transmit radio signals in accordance with a flexible spectrum use (FSU) protocol.

The apparatus 10 and the transmitter 16 may be operationally coupled and any number or combination of intervening elements may exist (including no intervening elements).

Fig. 2 illustrates an exemplary apparatus 100. The apparatus 100 illustrated in Fig. 2 may be an electronic device. In some embodiments of the invention, the apparatus 100 is a hand portable electronic device such as a mobile telephone, personal gaming device, personal music player or a personal digital assistant.

1 5 The apparatus 1 00 illustrated in Fig. 2 comprises a controller 11 0, a user input device 112, a transmitter 116, a receiver 118 and a memory 120. The elements 110, 112, 116, 118 and 120 may be operationally coupled and any number or combination of intervening elements may exist (including no intervening elements).

The controller 11 0 may, for example, be an apparatus 1 0 (such as that described above and illustrated in Fig. 1) in the form of processing circuitry.

The controller 11 0 is configured to receive inputs from the user input device 11 2 and the receiver 11 8. The controller 11 0 is configured to provide outputs to a user output device 114 and a transmitter 11 6. The controller 110 is configured to read from and to write to the memory 120.

The user input device 112 may be configured to receive an input from a user.

It may, for example, be a keypad, touch pad or any other type of user input apparatus. The user output device 114 is configured to convey information to a user. The user output device 114 may, for example, be an internal or external display. In some embodiments of the invention, the user input device 11 2 and the user output device 114 provide a user interface 11 5.

In some embodiments of the invention, the functions of the user interface 11 5 may be combined into a single device. For example, the user interface 115 may be provided by a touch screen display device.

The transmitter 116 may be configured to transmit radio frequency signals.

For instance, the transmitter 11 6 may be configured to transmit radio signals in accordance with a flexible spectrum use (FSU) protocol. In some exemplary embodiments of the invention, the transmitter 116 may be configured to transmit radio signals in accordance with an IEEE (Institute of Electrical and Electronics Engineers) 802.11 or 802.16 communication protocol.

In some embodiments of the invention, the transmitter 116 is configured to receive short range radio frequency signals. For example, short range radio frequency signals may be considered to be radio frequency signals having a transmission range of 100 meters or less. Alternatively, short range radio frequency signals may be considered to be radio frequency signals having a transmission range of 50 meters or less. Alternatively, short range radio frequency signals may be considered to be radio frequency signals having a transmission range of 1 0 meters or less.

The receiver 118 may be configured to receive radio frequency signals. For instance, receiver 11 8 may be configured to receive radio signals in accordance with a flexible spectrum use (FSU) protocol. In some embodiments of the invention, the receiver 11 8 is configured to receive short range radio frequency signals, such as those described above. In some exemplary embodiments of the invention, the receiver 118 may be configured to receive radio signals in accordance with an IEEE (Institute of Electrical and Electronics Engineers) 802.11 or 802.16 communication protocol.

Some or all of the components of the transmitter 116 and the receiver 118 may be shared. For example, the functions of the transmitter 11 6 and the receiver 118 may be provided by a transceiver 119.

The memory 120 in Fig. 2 is illustrated as storing a computer program 122, message data 126, reception reservation signal data 128 and transmission reservation signal data 130.

The computer program 122 comprises computer program instructions 124 that control the operation of the apparatus 100 when loaded into the controller 110. The computer program instructions 124 may provide the logic and routines that enables the apparatus 100 to perform one or both of the methods illustrated in Fig 5A and Fig. 5B. The controller 110 by reading the memory 120 is able to load and execute the computer program 122.

The computer program 122 may arrive at the apparatus 100 via any suitable delivery mechanism 140. The delivery mechanism 140 may be, for example, a computer-readable storage medium, a computer program product, a memory device, a record medium such as a CD-ROM or DVD, an article of manufacture that tangibly embodies the computer program 122. The delivery mechanism 140 may be a signal configured to reliably transfer the computer program 122. The apparatus 100 may propagate or transmit the computer program 122 as a computer data signal.

Although the memory 120 is illustrated as a single component it may be implemented as one or more separate components some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/ dynamic/cached storage.

Fig. 3 illustrates a further exemplary apparatus 200. The apparatus 200 illustrated in Fig. 3 may be an electronic device. The apparatus 200 may, for example, be an access point of a network. The access point may provide access to the Internet and/or an intranet. The apparatus 200 may, for instance, be powered by mains electricity.

The apparatus 200 illustrated in Fig. 3 comprises a controller 210, a transmitter 216, a receiver 218 and a memory 220. The elements 210, 216, 218 and 220 may be operationally coupled and any number or combination of intervening elements may exist (including no intervening elements).

The controller 210 may, for example, be an apparatus 10 (such as that illustrated in Fig. 1) in the form of processing circuitry. The controller 210 is configured to receive an input from the receiver 218 and to provide an output to the transmitter 216. The controller 210 is configured to read from and to write to the memory 220.

The transmitter 216 may be configured to transmit radio frequency signals.

For instance, the transmitter 216 may be configured to transmit radio signals in accordance with a flexible spectrum use (FSU) protocol. In some embodiments of the invention, the transmitter 216 is configured to transmit short range radio frequency signals, such as those described above in relation to Fig. 2.

The receiver 218 may be configured to receive radio frequency signals. For instance, the receiver 218 may be configured to receive radio signals in accordance with a flexible spectrum use (FSU) protocol. In some embodiments of the invention, the receiver 218 is configured to receive short range radio frequency signals, such as those described above in relation to Fig. 2.

Some or all of the components of the transmitter 216 and the receiver 218 may be shared. For example, the functions of the transmitter 116 and the receiver 118 may be provided by a transceiver 219.

The memory 220 in Fig. 3 is illustrated as storing a computer program 222, message data 126, reception reservation signal data 128 and transmission reservation signal data 130.

The computer program 222 comprises computer program instructions 224 that control the operation of the apparatus 200 when loaded into the controller 210. The computer program instructions 224 may provide the logic and routines that enables the apparatus 200 to perform one or both of the methods illustrated in Fig 5A and Fig. SB. The controller 210 by reading the memory 220 is able to load and execute the computer program 222.

The computer program 222 may arrive at the apparatus 200 via any suitable delivery mechanism 240. The delivery mechanism 240 may be, for example, a computer-readable storage medium, a computer program product, a memory device, a record medium such as a CD-ROM or DVD, an article of manufacture that tangibly embodies the computer program 222. The delivery mechanism 240 may be a signal configured to reliably transfer the computer program 222. The apparatus 200 may propagate or transmit the computer program 222 as a computer data signal.

Although the memory 220 is illustrated as a single component it may be implemented as one or more separate components some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/ dynamic/cached storage.

References to computer-readable storage medium', computer program product', tangibly embodied computer program' etc. or a controller', processor', processing circuitry' etc. should be understood to encompass not only computers having different architectures such as single/multi-processor architectures and sequential (Von Neumann)/parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc. Exemplary methods according to embodiments of the present invention will now be described in relation to Figs 4A to 6B.

Fig. 4A illustrates, as an example, a first apparatus 100, a second apparatus 200, a third apparatus 300 and a fourth apparatus 400. The first apparatus illustrated in Fig. 4A may take the same form as the apparatus 100 illustrated in Fig. 2. The second apparatus 200 illustrated in Fig. 4A may take the same form as the apparatus 200 illustrated in Fig. 3.

In this example, the first apparatus 100 may, for instance, be a portable electronic device. The second apparatus 200 may, for instance, be an access point for providing access to one or more remote servers (perhaps via the internet).

A wireless communication link 50 may be established between the first apparatus 100 and the second apparatus 200 on a radio channel. The radio channel may be used to transfer data on the wireless communication link 50 between the first apparatus 100 and the second apparatus 200.

The wireless communication link 50 may, for example, be time division multiplexed, frequency division multiplexed and/or code division multiplexed.

The radio channel used for the wireless communication link 50 may be defined by one or more parameters, such as, for instance: one or more time slot schedules, one or more frequencies and/or one or more codes. The first and second apparatuses 100, 200 may be considered to form a first network 70.

In this example, the second apparatus 200 may provide content to the first apparatus 100 on the wireless communication link 50, such as video, audio or text. In other examples, the first apparatus 100 may provide content to the second apparatus 200 on the wireless communication link 50. The content may be streamed.

The wireless communication link 50 may be predominantly used, in this example, to transfer data from the second apparatus 200 to the first apparatus 100, although some data also may be transferred in the opposite direction.

Consequently, the first apparatus 100 may be considered to be a "receiving apparatus" and the second apparatus 200 may be considered to be a "transmitting apparatus" in the first network 70.

The radio channel used for the wireless communication link 50 may have a frequency (or frequencies) within a radio band that is not specifically allocated to a particular purpose. For example, the radio channel may operate at a frequency (or frequencies) in one or more of the industrial, scientific and medical (ISM) radio bands defined by the International Telecommunication Union (ITU).

Prior to or after establishing the wireless communication link 50 between the first apparatus 100 and the second apparatus 200, the controller 110 of the first apparatus 100 (a "receiving apparatus" in the first network 70) may control the transmitter 116 to broadcast at least one reception reservation signal 128, such as, for example a beacon. The line denoted with the reference numeral 129 relates to the broadcast of the at least one reception reservation signal 128.

The line 129 demarcates (part of) an area within which it may be possible for other apparatuses 300, 400 to receive the at least one reception reservation signal 128 clearly. The area encompassed by the line 129 depends upon the power at which the at least one reception reservation signal 128 is broadcast and the direction in which it is broadcast. Outside the area defined by the line 129, the signal to noise ratio (SNR) of the at least one reception reservation signal 128 is not considered to be sufficient for the at least one reception reservation signal 128 to be clearly received by other apparatuses 300, 400.

Alternatively or additionally, a threshold may be defined, against which the strength of a detected signal is compared. For example, a detected reception reservation signal 128 with a signal strength below the threshold may be considered to be invalid.

The first apparatus 100 broadcasts the at least one reception reservation signal 128 in order to reserve its right to receive data on the radio channel used for the wireless communication link 50. The at least one reception reservation signal 128 may include data that is for informing other apparatuses that the radio channel used for the wireless communication link is occupied. The at least one reception reservation signal 128 may or may not include data identifying the first apparatus 1 00 to other apparatuses.

The first apparatus 100 may broadcast reception reservation signals 128 according to a schedule. For example, the first apparatus 100 may broadcast reception reservation signals 1 28 periodically.

Prior to or after establishing the wireless communication link 50 between the first apparatus 100 and the second apparatus 200, the controller 210 of the second apparatus 200 (a "transmitting apparatus" in the first network 70) may control the transmitter 216 to broadcast at least one transmission reservation signal 130, such as, for example a beacon. The line denoted with the reference numeral 131 relates to the broadcast of the at least one transmission reservation signal 130.

The line 131 demarcates (part of) an area within it may be possible for other apparatuses 300, 400 to receive the at least one transmission reservation signal 130 clearly. The area encompassed by the line 131 depends upon the power at which the at least one transmission reservation signal 130 is broadcast and the direction in which it is broadcast. Outside the area defined by the line 131, the signal to noise ratio (SNR) of the at least one transmission reservation signal 130 is not considered to be sufficient for the at least one transmission reservation signal 130 to be clearly received by other apparatuses 300, 400. Alternatively or additionally, a threshold may be defined, against which the strength of a detected signal is compared. For example, a detected transmission reservation signal 130 with a signal strength below the threshold may be considered to be invalid.

The second apparatus 200 broadcasts the at least one transmission reservation signal 1 30 in order to reserve its right to transmit data on the radio channel used for the wireless communication link 50. The at least one transmission reservation signal 130 may include data that is for informing other apparatuses that the radio channel used for the wireless communication link 50 is occupied. The at least one transmission reservation signal 1 30 may or may not include data identifying the second apparatus 100 to other apparatuses.

The second apparatus 200 may broadcast transmission reservation signals according to a schedule. For example, the second apparatus 200 may broadcast transmission reservation signals 1 30 periodically.

In some exemplary embodiments of the invention, the at least one reception reservation signal 128 and/or the at least one transmission reservation signal may be broadcast on the radio channel used for the wireless communication link 50 (or in the event that the wireless communication link 50 has not yet been fully established, the radio channel that is proposed to be used for the wireless communication link 50). In these exemplary embodiments of the invention, mere reception of the at least one reception reservation signal 1 28 or the at least one transmission reservation signal 1 30 by another apparatus may indicate occupation of that radio channel to that apparatus.

In another exemplary embodiment of the invention, the at least one reception reservation signal 128 and/or the at least one transmission reservation signal may be broadcast on a different radio channel to that used for the wireless communication link 50.

The third and fourth apparatuses 300, 400 illustrated in Fig. 4A receive the at least one reception reservation signal 128 and the at least one transmission reservation signal 130.

In this example, at least one reception reservation signal 128 indicates to an apparatus receiving it (other than the second apparatus 200) that at least one transmission reservation signal 130, reserving the right to transmit on the radio channel indicated by the at least one reception reservation signal 130, should not be broadcast. It may also indicate that other types of data should not be transmitted. In some circumstances, reception of at least one reception reservation signal 128 by an apparatus (other than the second apparatus 200) may, at least temporarily, prevent that apparatus from broadcasting at least one transmission reservation signal 130. This prevents the third and fourth apparatuses 300, 400 from broadcasting conflicting transmission reservation signals 130 reserving the right to transmit on the radio channel used for the wireless communication link 50. It may also prevent the third and fourth apparatuses 300, 400 from making a transmission that may cause interference at the first apparatus 1 00.

In this particular example, reception of at least one reception reservation signal 128 does not, however, prevent other apparatuses 300, 400 from broadcasting at least one reception reservation signal 128.

In this example, at least one transmission reservation signal 1 30 may indicate to an apparatus receiving it (other than the first apparatus 1 00) that at least one reception reservation signal 128, reserving the right to receive on the radio channel indicated by the at least one reception reservation signal 130, should not be broadcast. In some circumstances, reception of at least one transmission reservation signal 130 by an apparatus (other than the first apparatus 100) may, at least temporarily, prevent that apparatus from broadcasting at least one reception reservation signal 128. This prevents the third and fourth apparatuses 300, 400 reserving the right to receive on the 1 0 radio channel used for the wireless communication link 50.

In this particular example, reception of at least one transmission reservation signal 130 does not, however, prevent other apparatuses 300, 400 from broadcasting at least one transmission reservation signal 1 30.

Fig. 4B illustrates the first, second, third and fourth apparatuses 1 00, 200, 300 and 400 that may be illustrated in Fig 4A. However, in the example illustrated in Fig. 4B, the relative positioning of the apparatuses 100, 200, 300, 400 is different.

In the Fig. 4B example, the first apparatus 100 broadcasts at least one reception reservation signal 128 in the manner described above in relation to Fig. 4A. This is indicated in Fig. 4B by the line 129. The second apparatus broadcasts at least one transmission reservation signal 130 in the manner described above in relation to Fig. 4A. This is indicated by the line 131.

Neither the third apparatus 300 nor the fourth apparatus 400 receive the at least one transmission reservation signal 130, because in the illustrated example they are both situated outside the area demarcated by the line 131.

The fourth apparatus 400 does not receive a valid reception reservation signal 128, because it is situated outside the area demarcated by the line 129.

The third apparatus 300 receives the at least one reception reservation signal 128 broadcast by the first apparatus 100. The at least one reception reservation signal 128 indicates to the third apparatus 300 that it should not broadcast at least one transmission reservation signal 128, reserving the right to transmit on the radio channel indicated by the at least one reception reservation signal 128. Reception of the at least one reception reservation signal 128 may prevent the third apparatus 300 (at least temporarily) from broadcasting at least one transmission reservation signal 1 30.

In this example, reception of at least one reception reservation signal 128 broadcast by an apparatus (such as that broadcast by the first apparatus 100) does not prevent another apparatus (such as the third apparatus 300) from broadcasting at least one reception reservation signal 128.

The third apparatus 300 establishes a wireless communication link 55 with the fourth apparatus 400. The third apparatus 300 and the fourth apparatus 400 may be considered to form a second network 80. The radio channel used for the wireless communication link 55 in the second network 80 may be the same as that used for the wireless communication link 50 in the first network 70.

The wireless communication link 55 may be established to transfer content (such as video, audio and/or text) from the fourth apparatus 400 to the third apparatus 300. The third apparatus 300 may therefore be considered to be a "receiving apparatus" of the second network 80 and the fourth apparatus 400 may be considered to be a "transmitting apparatus" of the second network 80.

Prior to or after establishing the wireless communication link 55, the third apparatus 300 may broadcast at least one reception reservation signal 128, reserving a right to receive on the radio channel used for the wireless communication link 55 in the second network 80. Also, the fourth apparatus 400 may broadcast at least one transmission reservation signal 130, reserving a right to transmit on a radio channel used for the wireless communication link in the second network 80.

In this example, the power at which the reservation signals 128, 130 may be broadcast by the third and fourth apparatuses 300, 400 may be the same or lower than the power at which the reservation signals 128, 130 were broadcast by the first and second apparatuses 100, 200. Consequently, even if the radio channel used for the wireless communication link 55 in the second network 80 may be the same as that used for the wireless communication link in the first network 70, no channel allocation conflict need arise.

For example, it may be that the at least one reception reservation signal 128 broadcast by the third apparatus 300 does not reach the second apparatus 200, 50 the second apparatus 200 is not prevented from broadcasting its transmission reservation signals 1 30. Similarly, it may be that the at least one transmission reservation signal 130 transmitted by the fourth apparatus 400 does not reach the first apparatus 100, so the first apparatus 100 is not prevented from broadcasting its reception reservation signals 1 28.

Fig. 4C illustrates the first, second, third and fourth apparatuses 1 00, 200, 300 and 400 in an exemplary situation where the relative positioning of the apparatuses 100, 200, 300, 400 may be different to that illustrated in Figs 4A and 4B.

In the Fig. 4C example, the first apparatus 100 broadcasts at least one reception reservation signal 128 in the manner described above in relation to Fig. 4A and 4B. This is indicated in Fig. 4C by the line 129. The second apparatus 200 broadcasts at least one transmission reservation signal 1 30 in the manner described above in relation to Fig. 4A and Fig. 4B. This is indicated by the line 131.

Neither the third apparatus 300 nor the fourth apparatus 400 receive the at least one reception reservation signal 128, because in the illustrated example they are both situated outside the area demarcated by the line 129. The third apparatus 300 does not receive a valid transmission reservation signal 130, because it is situated outside the area demarcated by the line 131.

The fourth apparatus 400 receives the at least one transmission reservation signal 130 broadcast by the second apparatus 200. The at least one transmission reservation signal 130 indicates to the fourth apparatus 400 that it should not broadcast at least one reception reservation signal 128, reserving the right to receive on the radio channel indicated by the at least one transmission reservation signal 130. Reception of the at least one transmission reservation signal 1 30 may prevent the fourth apparatus 400 (at least temporarily) from broadcasting at least one reception reservation signal 128.

In this example, reception of at least one transmission reservation signal 130 broadcast another apparatus (such as that broadcast by the second apparatus 200) does not prevent the fourth apparatus 400 from broadcasting at least one transmission reservation signal 130.

The fourth apparatus 400 establishes a wireless communication link 55 with the third apparatus 300. The third apparatus 300 and the fourth apparatus 400 may be considered to form a second network 80. The radio channel used for the wireless communication link 55 in the second network 80 may have the same parameters (for instance, time slot schedule, frequency and/or code) and the radio channel used for the wireless communication link 50 in the first network 70.

Prior to or after establishing the wireless communication link 55, the third apparatus 300 may broadcast at least one reception reservation signal 128, reserving a right to receive on a radio channel used for the wireless communication link 55 in the second network 80. Also, the fourth apparatus 400 may broadcast at least one transmission reservation signal 130, reserving a right to transmit on a radio channel used for the wireless communication link 55 in the second network 80.

In this example, as in the Fig. 4B example, the power at which the reservation signals 128, 130 may be broadcast by the third and fourth apparatuses 300, 400 may be the same or lower than the power at which the reservation signals 128, 130 were broadcast by the first and second apparatuses 100, 200.

Consequently, even if the radio channel used for wireless communication link in the second network 80 may be the same as the radio channel used for the wireless communication link 50 in the first network, no channel allocation conflict need arise.

Embodiments of the invention described above in relation to Figs. 4A, 4B and 40 provide an efficient system for allocating radio channels. According to these exemplary embodiments of the invention, reservation signals 128, 130 may be used to indicate that a radio channel is occupied, enabling apparatuses to determine available radio channels for transferring data in a particular area.

Figs 5A, and 5B illustrate blocks of a method. Fig. 6A, 6B and Fig 6C illustrate the first and second apparatuses 100, 200 in an exemplary situation where the distance between them is relatively small.

Fig. 6A relates to an exemplary situation where the first apparatus 100 has broadcast at least one reception reservation signal 128 (as indicated by the line 129 in Fig. 6A) and the second apparatus 200 has broadcast at least one transmission reservation signal 130 (as indicated by the line 131 in Fig. 6A).

It may be seen from Fig. 6A that the area over which the at least one reception reservation signal 128 is broadcast may be slightly different to the area over which the at least one transmission reservation signal 130 is broadcast. The difference is not great, due to the relative proximity of the first and second apparatus 100, 200.

The first apparatus 1 00 may be broadcasting reception reservation signals 128 according to a schedule (for example, periodically) and the second apparatus 200 may be broadcasting transmission reservation signals 130 according to a schedule (for example, periodically).

At block 500 of Fig. 5A, the controller 11 0 of the first apparatus 1 00 may control the transmitter 11 6 to transmit at least one message 1 26 to the second apparatus on a radio channel used for the wireless communication link 50.

The message 126 may be for transferring responsibility for broadcasting reception reservation signals 128 from the first apparatus 100 to the second apparatus 200. Transmission of the message 1 26 is illustrated in Fig. 6B.

For example, the message 126 may be a request, asking the second apparatus 200 to assume responsibility for broadcasting reception reservation signals 128.

When the message 126 is received by the receiver 218 of the second apparatus 200, the second apparatus 200 may assume responsibility for broadcasting reception reservation signals 1 28 on behalf of the first apparatus 100.

In some embodiments of the invention, the second apparatus 200 may assume responsibility for broadcasting reception reservation signals 128 on behalf of the first apparatus 100 whenever the first apparatus 1 00 instructs it to do so. Alternatively, in other exemplary embodiments of the invention, the second apparatus 200 may only assume responsibility for broadcasting reception reservation signals 128 from the first apparatus 100 if one or more conditions are fulfilled.

For example, prior to assuming responsibility for broadcasting reception reservation signals 1 28 on behalf of the first apparatus 1 00, the controller 21 0 of the second apparatus 200 may analyze at least one radio signal from the first apparatus (such as the message 126). The controller 210 may analyze at least one of: a received signal strength, a phase and a time of flight of the radio signal.

The controller 210 may be configured to analyze the radio signal in such a way that if the distance between the first apparatus 100 and the second apparatus 200 is below a threshold, the second apparatus 200 assumes responsibility for broadcasting reception reservation signals 1 28 on behalf of the first apparatus 100. Otherwise, the controller 210 of the second apparatus 200 may control the transmitter 216 to transmit a reply message indicating that the second apparatus 200 does not accept the transfer of responsibility.

At block 510 of Fig. 5B, second apparatus 200 assumes responsibility for broadcasting reception reservation messages 128 on behalf of the first apparatus 100. In this example, the controller 210 of the second apparatus may control the transmitter 21 6 to transmit a reply message to the first apparatus 1 00, confirming that responsibility for broadcasting reception reservation signals 128 has been handed over to the second apparatus 200.

In response to receipt of the reply message at the first apparatus 100, the controller 110 may cease controlling the transmitter 11 6 to broadcast further reception reservation signals 128, SO that no further reception reservation signals are broadcast by the first apparatus 100.

Before the second apparatus 200 broadcasts at least one reception reservation signal 128, on behalf of the first apparatus 100, the controller 210 of the second apparatus 200 may determine whether a radio channel is available for broadcasting at least one reception reservation signal 128.

The controller 210 may determine whether a radio channel is available by controlling the receiver 218 to scan for transmission reservation signals 130, to check that an apparatus in its vicinity has not reserved the right to undisturbed transmission on the radio channel used for the wireless communication link 50.

If no transmission reservation signals 130 are received reserving the radio channel being used for the wireless communication link 50, the controller 21 0 may determine that a radio channel for broadcasting at least one reception reservation signal 128 is available.

At block 520 of Fig. 5B, the controller 210 of the second apparatus 200 may control the transmitter 216 to broadcast at least one reception reservation signal 128. The at least one reception reservation signal 128 may be broadcast on the same radio channel as that used for the wireless communication link 50, or a different radio channel. Fig. 6B illustrates the second apparatus 200 broadcasting at least one reception reservation signal 128.

Fig. 6C illustrates the second apparatus 200 broadcasting at least one reception reservation signal 128 and at least one transmission reservation signal 130 over the same area (although this need not necessarily be the case), as indicated by the line denoted with the reference numerals 129 and 131.

It may be that the first apparatus 100 is battery powered (for example, if the first apparatus 100 is a hand portable device) and the second apparatus 200 may be mains powered and/or battery powered. Embodiments of the invention enable the responsibility for broadcasting at least one reservation signal 128, 130 to be transferred from the first apparatus 100 to the second apparatus 200. This enables the first apparatus 100 to the save power, because it no longer needs to broadcast reservation signals.

The blocks illustrated in Figs 5A and 5B may represent steps in a method and/or sections of code in a computer program 122, 222. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given may be made without departing from the scope of the invention as claimed. For example, in the text above, the first apparatus 100 is described as being a "receiving apparatus" in the first network 70 and the second apparatus 200 is described as being a "transmitting apparatus". The first apparatus 1 00 may transfer responsibility for broadcasting reception reservation signals 128 to the second apparatus 200.

In alternative embodiments of the invention, the first apparatus 100 may be a "transmitting apparatus" in first network 70 and second apparatus 200 may be a "receiving apparatus". For example, the first apparatus 100 may be a portable electronic device streaming video data to the second apparatus 200, which may be an access point. The first apparatus 100 may transfer responsibility for broadcasting transmission reservation signals 1 30 to the second apparatus 200.

The text above relating to Figs 4A, 4B and 4C describes the first apparatus broadcasting at least one reception reservation signal 128 in order to reserve the right to receive on a radio channel. The first apparatus 100 may, for example, be configured to determine, prior to broadcasting the at least one reception reservation signal 128, that at least one transmission reservation signal 130 reserving the same radio channel has not been broadcast by another apparatus.

The text above relating to Figs 4A, 4B and 40 also describes the second apparatus 200 broadcasting at least one transmission reservation signal 130 in order to reserve the right to receive on a radio channel. The second apparatus 200 may, for example, be configured to determine, prior to broadcasting the at least one transmission reservation signal 1 30, that at least one reception reservation signal 128 reserving the same radio channel has not been broadcast by another apparatus.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

I/we claim:

Claims

CLAIMS1. An apparatus configured to control a transmitter to broadcast at least one reservation signal for reserving a radio channel, and configured to control the transmitter to transmit at least one message to a further apparatus, enabling transfer of responsibility, from the apparatus to the further apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

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2. An apparatus as claimed in claim 1, wherein the apparatus is configured, in response to responsibility for broadcasting the at least one reservation signal being transferred from the apparatus to the further apparatus, to cease controlling the transmitter to broadcast reservation signals.

3. An apparatus as claimed in claim 1 or 2, wherein the apparatus is configured to determine, from receipt of a reply message from the further apparatus, that responsibility for broadcasting reservation signals for reserving a radio channel has been transferred to the further apparatus.

4. An apparatus as claimed in claim 1, 2 or 3, wherein the apparatus is configured to transmit the at least one message to the further apparatus after a wireless communication link has been established, on a radio channel, between the apparatus and the further apparatus.

5. An apparatus as claimed in any of the preceding claims, wherein the at least one reservation signal is for reserving a right to undisturbed reception on a radio channel, or for reserving a right to transmit on a radio channel.

6. An apparatus as claimed in any of the preceding claims, wherein the at least one reservation signal is a beacon.

7. An apparatus as claimed in any of the preceding claims, wherein the apparatus is processing circuitry.

8. An electronic device comprising a transmitter and the apparatus as claimed in claim 7.

9. A method, comprising: controlling a transmitter to transmit at least one message from an apparatus to a further apparatus, enabling transfer of responsibility, from the apparatus 1 0 to the further apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

10. A method as claimed in claim 9, further comprising: ceasing to control the transmitter to broadcast reservation signals, in response to responsibility 1 5 for broadcasting the at least one reservation signal being transferred from the apparatus to the further apparatus.

11. A method as claimed in claim 9 or 10, further comprising: determining, from receipt of a reply message from the further apparatus, that responsibility for broadcasting the at least one reservation signal for reserving a radio channel has been transferred to the further apparatus.

12. A method as claimed in claim 9, 10 or 11, wherein the at least one message is transmitted to the further apparatus after a wireless communication link has been established, on a radio channel, between the apparatus and the further apparatus.

13. A method as claimed in any of claims 9 to 12, wherein the at least one reservation signal is for reserving a right to undisturbed reception on a radio channel, or for reserving a right to transmit on a radio channel.

14. A method as claimed in any of claims 9 to 13, wherein the at least one reservation signal is a beacon.

15. A computer program that, when executed by a processor, enables the method as claimed in any of claims 9 to 14 to be performed.

1 6. A computer program comprising computer program instructions that, when executed by a processor, enable: controlling a transmitter to transmit at least one message from an apparatus 1 0 to a further apparatus, enabling transfer of responsibility, from the apparatus to the further apparatus, for broadcasting at least one reservation signal for reserving a radio channel.

17. A computer program as claimed in claim 16, wherein the computer 1 5 program instructions further enable: ceasing to control the transmitter to broadcast reservation signals, in response to responsibility for broadcasting the at least one reservation signal being transferred from the apparatus to the further apparatus.

18. A computer program as claimed in claim 16 or 17, wherein the computer program instructions further enable: determining, from receipt of a reply message from the further apparatus, that responsibility for broadcasting the at least one reservation signal for reserving a radio channel has been transferred to the further apparatus.

19. A computer program as claimed in claim 16, 17 or 18, wherein the at least one message is transmitted to the further apparatus after a wireless communication link has been established, on a radio channel, between the apparatus and the further apparatus.

20. A computer program as claimed in any of claims 16 to 19, wherein the at least one reservation signal is for reserving a right to undisturbed reception on the radio channel.

21. A computer program as claimed in any of claims 16 to 20, wherein the at least one reservation signal is a beacon.

22. A tangible computer readable medium storing the computer program as claimed in any of claims 16 to 21.

23. An apparatus configured, in response to receipt of at least one message from another apparatus, to assume responsibility, from the another apparatus, for broadcasting at least one reservation signal for reserving a radio channel, and the apparatus being configured to control a transmitter to broadcast the at 1 5 least one reservation signal for reserving a radio channel.

24. An apparatus as claimed in claim 23, wherein the apparatus is configured to assume responsibility for broadcasting the at least one reservation signal for reserving a radio channel, after determining that at least one condition has been fulfilled.

25. An apparatus as claimed in claim 24, wherein the apparatus is configured to analyze a radio signal from the another apparatus to determine that the at least one condition has been fulfilled.

26. An apparatus as claimed in claim 25, wherein the apparatus is configured to analyze the radio signal by determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

27. An apparatus as claimed in any of claims 23 to 26, wherein the apparatus is configured, prior to broadcasting the at least one reservation signal for reserving a radio channel, to determine that a radio channel is available for broadcasting the at least one reservation signal for reserving a radio channel.

28. An apparatus as claimed in claim 27, wherein the apparatus is configured to determine that a radio channel is available for broadcasting the at least one reservation signal by controlling a receiver to scan for reservation signals.

29. An apparatus as claimed in any of claims 23 to 28, wherein the at least one reservation signal is a beacon.

30. An apparatus as claimed in any of claims 23 to 29, wherein the apparatus is processing circuitry.

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31. An electronic device comprising a transmitter and the apparatus as claimed in claim 30.

32. A method, comprising: assuming responsibility from an apparatus, in response to receipt of at least one message from the apparatus, for broadcasting at least one reservation signal for reserving a radio channel; and controlling a transmitter to broadcast the at least one reservation signal for reserving a radio channel.

33. A method as claimed in claim 32, wherein responsibility for broadcasting the at least one reservation signal for reserving a radio channel is assumed, after determining that at least one condition has been fulfilled.

34. A method as claimed in claim 32 or 33, further comprising: analyzing a radio signal from the another apparatus to determine that the at least one condition has been fulfilled.

35. A method as claimed in claim 34, wherein analyzing the radio signal includes determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

36. A method as claimed in any of claims 32 to 35, further comprising: determining, prior to broadcasting the at least one reservation signal for reserving a radio channel, that a radio channel is available for broadcasting the at least one reservation signal for reserving a radio channel.

37. A method as claimed in claim 36, wherein determining that a radio channel is available for broadcasting the at least one reservation signal comprises controlling a receiver to scan for reservation signals.

38. A method as claimed in any of claims 32 to 37, wherein the at least one 1 5 reservation signal is a beacon.

39. A computer program that, when executed by a processor, enables the method as claimed in any of claims 32 to 38 to be performed.

40. A computer program comprising computer program instructions that, when executed by a processor, enable: assuming responsibility from an apparatus, in response to receipt of at least one message from the apparatus, for broadcasting at least one reservation signal for reserving a radio channel; and controlling a transmitter to broadcast the at least one reservation signal for reserving a radio channel.

41. A computer program as claimed in claim 40, wherein responsibility for broadcasting the at least one reservation signal for reserving a radio channel is assumed, after determining that at least one condition has been fulfilled.

42. A computer program as claimed in claim 40 or 41, wherein the computer program instructions further enable: analyzing a radio signal from the another apparatus to determine that the at least one condition has been fulfilled.

43. A computer program as claimed in claim 42, wherein analyzing the radio signal includes determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

44. A computer program as claimed in any of claims 40 to 43, wherein the 1 0 computer program instructions further enable: determining, prior to broadcasting the at least one reservation signal for reserving a radio channel, that a radio channel is available for broadcasting the at least one reservation signal for reserving a radio channel.

45. A computer program as claimed in claim 44, wherein determining that a radio channel is available for broadcasting the at least one reservation signal comprises controlling a receiver to scan for reservation signals.

46. A computer program as claimed in any of claims 40 to 45, wherein the at least one reservation signal is a beacon.

47. A tangible computer readable medium storing the computer program as claimed in any of claims 40 to 46.

48. An apparatus configured, in response to receipt of at least one message from another apparatus, to determine that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel, and the apparatus being configured, in response to determining that a radio channel is available for broadcasting the at least one reservation signal, to control a transmitter to broadcast the at least one reservation signal for reserving a radio channel.

49. An apparatus as claimed in claim 48, wherein the apparatus is configured to determine that a radio channel is available for broadcasting the at least one reservation signal by controlling a receiver to scan for reservation signals.

50. An apparatus as claimed in claim 48 or 49, wherein the apparatus is configured, in response to receipt of the at least one message from another apparatus, to assume responsibility, from the another apparatus, for broadcasting the at least one reservation signal for reserving a radio channel.

51. An apparatus as claimed in claim 50, wherein the apparatus is configured to assume responsibility for broadcasting the at least one reservation signal for reserving a radio channel, after determining that at least one condition has been fulfilled.

52. An apparatus as claimed in claim 51, wherein the apparatus is configured to analyze a radio signal from the another apparatus, in order to determine that the at least one condition has been fulfilled.

53. An apparatus as claimed in claim 52, wherein the apparatus is configured to analyze the radio signal by determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

54. An apparatus as claimed in any of claims 48 to 53, wherein the at least one reservation signal is a beacon.

55. An apparatus as claimed in any of claims 48 to 54, wherein the apparatus is processing circuitry.

56. An electronic device comprising a transmitter and the apparatus as claimed in claim 55.

57. A method, comprising: determining, in response to receipt of at least one message, that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel; and controlling, in response to determining that a radio channel is available for broadcasting the at least one reservation signal, a transmitter to broadcast the at least one reservation signal for reserving a radio channel.

58. A method as claimed in claim 57, wherein determining that a radio 1 0 channel is available for broadcasting the at least one reservation signal comprises controlling a receiver to scan for reservation signals.

59. A method as claimed in claim 57 or 58, further comprising: in response to receipt of the at least one message from the apparatus, assuming 1 5 responsibility from the apparatus for broadcasting the at least one reservation signal for reserving a radio channel.

60. A method as claimed in claim 59, wherein responsibility for broadcasting the at least one reservation signal for reserving a radio channel is assumed, after determining that at least one condition has been fulfilled.

61. A method as claimed in claim 60, wherein a radio signal from the apparatus is analyzed, in order to determine that the at least one condition has been fulfilled.

62. A method as claimed in claim 61, wherein analyzing the radio signal includes determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

63. A method as claimed in any of claims 57 to 62, wherein the at least one reservation signal is a beacon.

64. A computer program that, when executed by a processor, enables the method as claimed in any of claims 57 to 63 to be performed.

65. A computer program comprising computer program instructions that, when executed by a processor, enable: determining, in response to receipt of at least one message, that a radio channel is available for broadcasting at least one reservation signal for reserving a radio channel; and controlling, in response to determining that a radio channel is available for 1 0 broadcasting the at least one reservation signal, a transmitter to broadcast the at least one reservation signal for reserving a radio channel.

66. A computer program as claimed in claim 65, wherein determining that a radio channel is available for broadcasting the at least one reservation signal 1 5 comprises controlling a receiver to scan for reservation signals.

67. A computer program as claimed in claim 65 or 66, wherein the computer program instructions further enable: in response to receipt of the at least one message from the apparatus, assuming responsibility from the apparatus for broadcasting the at least one reservation signal for reserving a radio channel.

68. A computer program as claimed in claim 67, wherein responsibility for broadcasting the at least one reservation signal for reserving a radio channel is assumed, after determining that at least one condition has been fulfilled.

69. A computer program as claimed in claim 68, wherein a radio signal from the apparatus is analyzed, in order to determine that the at least one condition has been fulfilled.

70. A computer program as claimed in claim 69, wherein analyzing the radio signal includes determining at least one of: a received signal strength, a phase, and a time of flight of the radio signal.

71. A computer program as claimed in any of claims 65 to 70, wherein the at least one reservation signal is a beacon.

72. A tangible computer readable medium storing the computer program as claimed in any of claims 65 to 71.