WO2010025744A1

WO2010025744A1 - Method and apparatus for indicating wireless connectivity options

Info

Publication number: WO2010025744A1
Application number: PCT/EP2008/007168
Authority: WO
Inventors: Jarkko Kneckt; Jukka REUNAMÄKI; Mauri Honkanen
Original assignee: Nokia Corporation
Priority date: 2008-09-02
Filing date: 2008-09-02
Publication date: 2010-03-11

Abstract

The invention relates to a method comprising determining at least one or more connectivity parameters of at least one bidirectional wireless interface; forming a connectivity signal suitable for a unidirectional radio transmission including said connectivity parameters; selecting at least one transmission parameter; and broadcasting said signal via the unidirectional radio transmission interface using said selected transmission parameter.

Description

METHOD AND APPARATUS FOR INDICATING WIRELESS CONNECTIVITY

OPTIONS

Related Field

The present invention is related to wireless connections, and in particular to the indication of wireless connectivity options to an apparatus.

Background Art

For wireless connections between devices, a growing variety of methods and standards is available. Each method has its own advantages and characteristics, such as differing cost, coverage range, energy consumption, and many more. Therefore, many devices are equipped with a specific wireless connection interface or with several interfaces in parallel for flexible usage.

A wireless technology which is frequently included in devices is frequency modulated (FM) radio. Devices may include FM receivers for receiving standard broadcast transmissions of public radio programs. Also, many devices include short range FM transmitters, for example for streaming audio signals to an external device located in close vicinity. This may be useful when a device (e.g. a mobile phone or terminal) does not include adequate loud speakers, but another device has both an FM receiver module and speakers. Audio output from the device may then be broadcast via short range FM radio in the VHF (very high frequency) band and received and played by the speaker device such as a car radio. Both FM receivers and short range FM transmitters have comparably low power requirements and low implementation costs. The frequency range of such receivers and transmitters may for example be in the range of 87 MHz to 108 MHz for carrying monophonic or stereophonic sound broadcasts. Other frequency ranges are also possible, further examples are 76 to 90 MHz and 65.8 to 74 MHz.

One example application for bidirectional wireless interfaces such as wireless local area network (WLAN) or Bluetooth is ad-hoc connection between at least two devices. This usually includes a discovery process, where devices with suitable interfaces for communication are detected. When a device with suitable interface and/or protocol has been detected, e.g. by receiving a signal emitted by this device, a service discovery process may follow for determining the services supported by the device via the detected interface. A discovery process needs to be repeated periodically in order to ensure that devices which have recently moved into the covered range are detected.

Summary

A method is proposed which may in one embodiment comprise determining at least one or more connectivity parameters of at least one bidirectional wireless interface; forming a connectivity signal suitable for a unidirectional radio transmission including said connectivity parameters; selecting at least one transmission parameter; and broadcasting said signal via the unidirectional radio transmission interface using said selected transmission parameter.

As an example, the unidirectional radio transmission may be a frequency modulated radio transmission. The connectivity signal may then for example be formed according to the radio data system standard.

In exemplary embodiments, the connectivity parameters may include a current availability of the at least one bidirectional wireless interface, supported operating modes of the at least one bidirectional wireless interface, and/or a priority parameter for said at least one bidirectional wireless interface.

In some embodiments, the selecting of at least one transmission frequency parameter may comprise the selection of at least one transmission frequency. A transmission frequency may for example be selected by retrieving a predefined frequency from a memory. In another example, the selecting of a transmission frequency may further comprise scanning through a predefined range of frequencies, and checking whether one of said frequencies is available for use.

According to exemplary embodiments, the method may comprise repeating said determination of connectivity parameters after a predefined period of time, checking whether said connectivity parameters have changed; and if said connectivity parameters have changed, forming and transmitting another connectivity signal from said repeated determination of connectivity parameters.

As another aspect of an exemplary embodiment of the invention, a method is disclosed comprising receiving a broadcast connectivity signal at a unidirectional radio interface; extracting from said connectivity signal at least one connectivity parameter associated with at least one bidirectional wireless connection option; and activating at least one bidirectional wireless interface in accordance with said connectivity parameters. Again, the unidirectional radio interface may for example be a frequency modulated radio interface.

In some embodiments, the method may comprise storing said extracted at least one parameter.

Optionally, the method may further comprise activating said at least one bidirectional wireless interface when a connection is required by an application, and/or when a connection is requested by a user.

In some embodiments, the method may include retrieving at least some of said stored connectivity parameters.

The method may optionally further comprise checking or recognizing whether a received signal is a connectivity signal. Such a check may for example include matching at least a portion of said received signal against one or more signal sequences. Furthermore, the method may in exemplary embodiments comprise scanning a range of radio frequencies; and terminating said scanning upon detecting a predefined signal sequence on one of said frequencies.

In some embodiments, the connectivity signal may include a connectivity parameter indicating availability of an interface at a remote apparatus, and/or at least one connectivity parameter indicating supported operating modes of an interface at a remote apparatus, and/or a priority parameter indicating preference settings for at least one interface. If a priority parameter is included, the method may further comprise selecting an interface for activation based on said priority parameters.

As an example, the connectivity signal may be in accordance with the open data application feature of the radio data system standard.

All of the above described method steps may alternatively be performed by computer program code sections included in a computer program, for example when executed on a processor or controller.

According to another aspect of an exemplary embodiment of the invention, an apparatus is provided which may comprise: at least one unidirectional radio transmitter; at least one bidirectional wireless interface; wherein said apparatus is configured to broadcast connectivity parameters associated with said at least one bidirectional wireless interface via said unidirectional radio transmitter. The unidirectional radio transmitter may for example be a frequency modulated transmitter.

In some embodiments, the apparatus may further be configured to determine connectivity parameters of said at least one bidirectional wireless interface.

Also, the apparatus may be configured to form a connectivity signal including said connectivity parameters, and said connectivity signal may for example be in accordance with the open data application feature of the radio data system standard.

The apparatus may in some embodiments further be configured to detect a frequency or channel available for broadcasting said connectivity parameters. This may for example be achieved by the apparatus being configured to detect said frequency by scanning through a predefined range of frequencies.

According to another aspect of an exemplary embodiment of the invention, an apparatus may be provided which may, in some embodiments, comprise at least one unidirectional radio receiver; at least one bidirectional wireless interface; wherein said apparatus is configured to activate one or more of said at least one bidirectional wireless interfaces based on a connectivity signal received via said unidirectional radio receiver. The unidirectional receiver may for example be a frequency modulated receiver.

Further, the apparatus may be configured to extract connectivity parameters included in said connectivity signal. Optionally, the apparatus may include a memory element, and the apparatus may be configured to store the extracted connectivity parameters.

In some embodiments, the apparatus may include at least two bidirectional wireless interfaces, and the apparatus may be configured to select one of said interfaces for activation based on said extracted connectivity parameters.

The apparatus may also in some embodiments be configured to detect a frequency carrying said connectivity signal.

According to another aspect, an apparatus is proposed which may comprise means for receiving a broadcast connectivity signal; means for extracting from said connectivity signal at least one connectivity parameter associated with at least one bidirectional wireless connection option; and means for activating at least one wireless connection means in accordance with said connectivity parameters. Also, another apparatus is proposed which may comprise means for determining at least one or more connectivity parameters of at least one bidirectional wireless interface; means for forming a connectivity signal suitable for a unidirectional radio transmission including said connectivity parameters; means for selecting at least one transmission parameter; and means for broadcasting said signal using said selected transmission parameter.

Brief description of figures

In the following, exemplary embodiments of the inventions will be described in more detail with reference to the figures, in which:

Figure 1 is an exemplary system including two devices with wireless interfaces;

Figure 2 is a flow diagram showing an exemplary method embodiment for a broadcasting and a receiving device;

Figure 3 is a flow diagram illustrating a frequency selection process by way of example; and

Figures 4a to 4c present exemplary signal structures for a connectivity signal.

Detailed description of exemplary embodiments

In Figure 1, a system which may utilize embodiments of the invention is shown as an example. The exemplary system includes at least one first device 1 having a unidirectional radio transmitter module such as a frequency modulation (FM) transmitter 14, and at least one second device 2 having a corresponding radio receiver 24. Also, both devices 1 and 2 have one or more additional bidirectional wireless connection interfaces. In the present example, the first device may e.g. include a Bluetooth module 16, a wireless local area network (WLAN) module 15, and a wireless universal serial bus (WUSB) interface module 17. The second device may also include a WLAN module, a Bluetooth module, and a cellular communication module 27. Each of the interface modules may include one or more antennas for their required operating ranges, controllers, processing units, storage elements, and further electronic elements. Alternatively, a central controller or a processing unit of each device (processing units 20 and 10) may control some or all functions of one or more interface module. The dotted arrows shown in Figure 1 shall indicate the potential wireless connections between the different modules; a unidirectional transmission may occur between FM transmitter 14 and receiver 24, while bidirectional connections are possible between WLAN modules 15 and 25 or Bluetooth modules 16 and 26. The FM radio transmitter 14 in the first device 1 may be a short range/low power transmitter, i.e. a transmitter with limited transmission power and thus coverage range. Such transmitters are also known as low power device (LPD), short range device (SRD), or FM transmitter (FMTx). The coverage range is usually in the range of several meters or dozens of meters, although these values shall only be understood as an implementation example.

It shall be understood that the device 2 described above as the receiver device may also include a transceiver instead of a receiver 24, or may include separately both a receiver and a transmitter, or also several similar receivers/transmitters in parallel. The same applies to the transmitter device 1 vice versa. Furthermore, the additional wireless interface included in each device may differ widely and may depend on various factors such as quality of service by the application, energy or spatial considerations. Some examples for wireless interfaces are WLAN, Bluetooth, wireless universal serial bus (WUSB), Bluetooth Low Energy, near field communication like radio frequency identification (RFID) and any similar technologies, standards and protocols. Some logical interfaces may be able to share equipment on a physical level, such that e.g. a single antenna may be used for two different connection standards. Most of these bidirectional interfaces have limited coverage ranges in the order of some centimetres up to several hundred meters, and may thus be utilized for local wireless networking and data exchange between devices. The exact setup and functionality of the wireless interfaces are known in the art and will not be detailed here. As the inventive idea is not limited to specific wireless technologies, any connection interface suitable for setting up a wireless personal area network (WPAN) or for connecting to a local area network may be used in conjunction with the presented embodiments and their derivatives. Depending on the respective interface, suitable antennas and transmission modules as well as processing units, software or hardware controllers, and other elements may be included in the device.

The apparatuses having these or other wireless interfaces as described above may include any from a wide range of electronic devices. As examples, these may include mobile phones, personal digital assistants, audio/media players, game consoles, navigational systems, and other mobile devices; but also devices like car radios, personal home computers, control modules, hi-fi units, storage elements and any other apparatus that may require and support a direct wireless connection to another apparatus. An apparatus may therefore include various further components and modules which may or may not be connected to the wireless interfaces described. This includes cellular communication modules, wired communication interfaces, displays, touchscreens, keypads, keyboards and/or other input means, speakers, audio output terminals, processors, controllers, internal and removable memory elements, energy sources or connectors, and many more, this listing not being exhaustive in any sense. The setup and functionality of such apparatuses is also known in the art and will not need to be discussed in detail. In the example of Figure 1, receiving device 2 may be a mobile phone or another mobile device with a cellular communication unit 27. The device may thus include at least one memory element 21 connected to the processing unit 20, and a user interface module 23, which in turn may comprise user input and output elements such as a display, speakers, a microphone, and a keypad. Further, an energy supply such as a rechargeable battery 22 may be included in the device, and/or a power supply interface for recharging or powering the device from mains current. Broadcasting device 1 may be a device without user interaction, such as a storage element, but might as well be any other type of device, such as a second mobile phone, a car radio, or a computer. In the Figure 1, device 1 comprises besides the described interfaces a memory element 11 and an energy supply or power connector 12. The processing units 10 and 20 may be able to selectively activate and deactivate single modules of the device, e.g. deactivating interfaces when they are not in use.

As can be seen, both devices of the given example include a number of wireless interfaces, some of them allowing bidirectional data connections between device 1 and 2. However, if not all of the interfaces are activated when the devices are within each others coverage range, a connection may not be possible, since no device will be able to detect the connection capabilities of the respective other device. Example embodiments of the invention allow sharing connection capabilities even for deactivated wireless interfaces between devices as long as the FM modules 14 and 24 are active in a device, and the receiving device 2 is within the coverage range of the low power transmitter 14. Since FM modules, in particular low power transmitters, only have small energy demands and do not require complex setup procedures, these may set to be continuously activated.

Turning to figure 2, a flow diagram of an exemplary method embodiment for a broadcasting device and a receiving device is shown. Steps to the left of the dotted line may be performed by a broadcasting device, and steps on the right are performed by a receiving device. It shall be noted that broadcasting device, receiving device, and similar terms are again only to be understood as functional roles of a device, and do not necessarily refer to hardware or software based differences of devices as long as the devices are able to perform the respective functions of receiving or transmitting. A single device may for example have both a transmitter and a receiver (or a combined transceiver) adapted for short range unidirectional transmissions like for example FM transmission, and such a device may thus adopt any one of the two different functional roles, depending on the current situation and requirements. On the other hand, there may be embodiments where the two device types are strictly separated, such that one device only broadcasts the connectivity parameters and never receives any parameters, while the other device only listens for such FM signals and does not or cannot broadcast.

In a first step 200, a device which has at least one wireless connection interface and a short range unidirectional transmitter may determine its current connection capabilities. This step may for example include retrieving the current connection parameters for the at least one wireless interface, or checking which of the at least one available interfaces are currently activated. Also, the step may include determining further parameters or supplementary data, e.g. by measuring interferences or evaluating further received signals. The information may be buffered for immediate broadcasting or stored in a memory element, which is not shown Figure 2. After all parameters and necessary information has been determined, at least a part of the data may be processed (step 202) as required for broadcasting. Again, processed data may be stored/buffered or transmitted immediately. Processing may for example include encoding, performing calculations, data compression, adding markers or flags, or generally converting the parameters into a signal suitable for radio transmission. Example formats for transmitting the parameters will be given in more detail below.

The parameters encoded into the connectivity signal may include for example an identifier for identifying the transmitting device, an application identifier for indicating that the signal is a connectivity signal, and a number of parameters for each of the present wireless interfaces. The interface parameters may for example comprise one or more capability parameters indicating the capabilities of a specific interface, such as whether the interface is capable of operating in an ad-hoc mode (e.g. the independent basic service set (IBSS) network configuration according to the IEEE 802.11 standard family), operating in an infrastructure or access point mode, and/or operating in a mesh operation mode. A further parameter may specify whether the respective interface is currently available for usage. Also, priority or preference parameters may be included, indicating that a specific interface is to be preferred for a connection, or detailing an order of priority for using the interfaces. Optionally, connection parameters (e.g. port numbers, channels) may be transmitted as well which allow the receiving device to choose the correct settings for initiating a connection with the respective interface. The above parameters and any additional parameters may be coded into a signal as binary flags, with e.g. 1 indicating support for a certain capability and 0 indicating that the feature is not supported. However, in other embodiments some or all of the parameters may also be encoded in any other desirable form, such as multiple bits, non- binary codes, and others. The number of interfaces announced in the connectivity signal may depend on the given protocol, or different versions may be defined with different numbers of fields. This allows flexibility for adding further information on interfaces which are not yet known. Also, it is conceivable to include a parameter in the signal indicating the number of interfaces for which parameters are broadcast subsequently, and e.g. each set of capability and availability parameters may be preceded by an interface identifier indicating the corresponding interface type using a predefined bit code. Some examples for signal formats will be given below. In another example embodiment the parameter may include information that identifies a time when a specific interface will be available.

When the necessary parameters have been converted into a transmissible signal, broadcasting of the parameters may start. Selection of suitable transmission parameters, such as a suitable transmission frequency for the FM transmitter example, is thus performed in step 204. The frequency or any other settings used for broadcasting may be preset in some embodiments and for this purpose stored in and retrieved from an element of the broadcasting device. In other embodiments, an available frequency for broadcasting connection parameter signals may be selected by a frequency selection process, which will also be detailed below in conjunction with Figure 3. The subsequent actual transmission of the signal in step 206 is independent of the transmission parameter determination. It is also conceivable that a device may broadcast the signal with different transmission settings, link data rate, or on two or more different frequencies, for example in order to cover different protocols or frequency bands, or to ensure good availability of the signal even during interferences. When several transmitters are present, broadcasting on different frequencies may e.g. be performed simultaneously, but also alternately with predefined intervals and duration of transmission.

In some of the embodiments, the determination of current connectivity parameter data in step 202 may be repeated after a predetermined period of time, so that the broadcast connection data is updated regularly. This may ensure that an interface which has been deactivated in the mean time is not falsely announced as available in the connection signal. In other embodiments, the determination of connectivity parameter data may be performed only once during device setup, or in response to a certain event at the device (e.g. user input, interface activation or deactivation). Evidently, any new parameter data may be converted into a transmissible signal as above in step 202. In other embodiments, an additional matching step (not shown) may be included for checking whether the current parameter data has changed compared to previously broadcast data, and if no changes are detected, conversion and encoding of data might not be necessary. In other embodiments the transmission of the broadcast connection data is repeated after a predetermined period of time. The number of retransmissions might be limited or might be unlimited.

At the receiving device, the first step required for receiving connectivity parameters is to determine the correct receiving channel, for example the correct frequency for receiving signals in step 208 and to activate the related receiving module such as a FM receiver, if not active already. A special initiation process or any other setup is not necessary for a unidirectional radio reception. The transmission channel/frequency of the broadcasting device either needs to be predefined and known to the receiving device, or it needs to be found by the receiving device in some way. Either implementation may be used for any of the described embodiments. Also, a combination of these is conceivable, for example when a standard frequency is given, but a connectivity signal is still not detected or not received with sufficient quality. In such an embodiment, a device may first tune onto a predefined frequency, and if signal reception fails, a scanning procedure may be initiated. This may ensure that even connectivity signals which are not broadcast on the agreed frequencies can be received and used. It is also conceivable to provide frequency scanning in such a case only on user request.

A receiving device needs to be able to recognize a received connectivity signal, or at least to recognize that the correct frequency for receiving such signals has been selected. When only one single frequency is predefined on both ends, the frequency or signal does not need to be recognized in any way, but the device may then merely listen for connectivity signals on this frequency. Recognition of the correct signal and thus frequency may be ensured by providing a predefined signal sequence, e.g. an identifier at the beginning of the connectivity signal which clearly indicates to supporting devices that the following information is a connectivity signal.

Selection of frequencies may be performed in various ways on both sides. One option is to use a predetermined frequency step size allowed for broadcasting connectivity signals, as illustrated in Figure 3 for the broadcasting device. As an example, the frequencies may be divided by a step size of 0.5 MHz, so that the broadcasting frequency may be any of the frequencies 87 MHz, 87.5 MHz, 88 MHz, 88.5 MHz, 89 MHz, and so on until the limit of the available frequency band is reached. It will be understood that the upper and lower frequency limits as well as the frequency step size and position are given here by way of example only and shall not limit any embodiments of the invention in any way. The broadcasting device may first check whether there is a predefined transmission frequency stored for the transmission in step 302. If this is the case, it may tune to this frequency in step 304 and check whether it is free for use in step 306. If no predefined frequency has been set or if the frequency is not free for use for some reason, the device may then try to use frequencies starting from the lowest allowed frequency (i.e. 87 MHz in the example) in step 310. The allowed frequency range and step size may be retrieved from a memory element or register in step 308. If the first frequency is available (checked in step 312), the connectivity signal is broadcast at this frequency in step 320. If the frequency in question is already used and thus not available, the next frequency in line is selected by adding the step size value in step 314. This is repeated until a free frequency is found for transmission. Setting these or similar rules for frequency usage may accelerate the discovery process between the devices, because frequencies are chosen and scanned in a defined order. Broadcasting is then performed as described for step 206 of Figure 2 above. In some embodiments, it is also conceivable that a first run (or any predefined number of runs) is performed with the predefined step size, and if no available frequency is found on any of these frequencies when reaching the end of the allowed frequency range in step 316, the step size is lowered (step 318). In one example, this may correspond to lowering the step size from 1 MHz to 0.5 MHz. Alternatively, the frequency steps may be shifted slightly (not shown) while retaining the step size. It will be understood that not all of the steps described and shown in Figure 3 are required; for example, it may not be necessary to check for a predefined set frequency, but scanning for available frequencies as from step 308 may start immediately. Also, a device may in some embodiments stop looking for available frequencies if no usable frequency has been found when reaching the end of the allowable range in step 316. In this case, the device may be configured to repeat the frequency selection process after a preset period of time.

At the receiver, a very similar procedure may be performed. Again, it may first be checked whether a connectivity signal is received on a predefined channel (e.g. at a predefined frequency or on one from a set of several predefined frequencies). If this is not the case, the same frequencies as above for the detection of available frequencies are checked, for example in the same order for faster detection. Frequencies which are not covered by the predefined step size rule are not scanned at all. However, in some embodiments, and if no connectivity signal is found when all possible frequencies have been checked, the scanning step size may be decreased similar as for the transmitting device. In this way, also signals broadcast on frequencies between the predefined steps may be detected. Again, it is also possible to shift the scanned frequency range after an unsuccessful cycle, e.g. first scanning a set of frequencies and then turning to frequencies with a defined offset compared to the scanned set. For the example values given above, this would result in a first scanning cycle at 87.0 MHz, 88.0 MHz, 89.0 MHz and so on, and in a second scanning cycle e.g. 87.5 MHz, 88.5 MHz, 89.5 MHz, and so on. As mentioned before, any of these scanning processes may also be combined with the use of a preset broadcast frequency. Also, a limited set of predefined and stored frequencies may be given (which are not necessarily determined by any deterministic rules), and scanning is only performed through this predefined frequency set.

It will be seen that usually a receiver is more flexible in detecting frequencies than the broadcasting device is in selecting the same. When the transmitter is set to use only a specific single frequency, both a receiver knowing this frequency beforehand and a receiver working with a scanning process will be able to detect the correct frequency and receive the desired signal. On the other hand, a signal from the transmitter which is free to use any frequency within a certain frequency range might, depending on the actually selected frequency, only be received by chance or if the receiver is able to scan through the same range of frequencies. Also, it is evident that similar scanning and detection processes may be used for detecting the correct transmission channel and other transmission/reception parameters in any other unidirectional radio transmission method used for embodiments of the invention.

For the further description of the exemplary method embodiment, reference is again made to Figure 2. After receiving an identified connectivity signal at a device in step 210, the received signal may be stored and/or processed. Depending on the format of the signal, it may be decoded, decompressed, or handled otherwise as necessary. From a protocol or standard definition defined in advance, the device will then be able to extract all connectivity parameters and data included within the signal in step 212. Optionally, several formats or protocols may be supported, and a flag or sequence within the signal may indicate the specific protocol used. Finally, the extracted connectivity parameters and data may be used for initiating wireless connections or activating connection interfaces at the receiving device. Again, the actual use of the extracted data may depend on the desired functionality and also on the exact content of the connectivity signal. Basically, the connectivity parameters will allow the receiving device to determine which interfaces are present at the broadcasting device for initiating a connection. If at least one corresponding interface is also available at the receiving device, this interface may in response be activated automatically by a controller or processor of the device. In other embodiments (such as the one shown in Figure 2), activation of one or more interfaces might not be performed until a connection is actually required for some application. For such a delayed activation, received and extracted connectivity parameters may be stored in a volatile or non-volatile memory element in step 214. When new connectivity parameters are received from the same broadcasting device at a later time with another connectivity signal, a stored set of connectivity parameters may be updated accordingly as indicated by the back arrow to step 210. If particular capabilities have been indicated for a device, e.g. connection modes such as ad-hoc mode and mesh mode, the receiving device may also select the desired mode as long as support is shown in the parameters. When a connection is required or desired for exchanging data (step 216), the previously stored connectivity parameters may be retrieved from memory in step 218. The receiving device may then check in step 220 whether the connectivity parameters indicate a possible connection which would match the current requirements of the application, e.g. based on data transmission rate, and whether a corresponding interface is available in the device. If this is the case, the correct connection interface may be activated (step 222), and a connection may be initiated as known in the art in step 224.

In some embodiments, priority parameters may be used for handling several connection interfaces in a single device. Without such a parameter, a device receiving connectivity parameters signalling availability of two different wireless interfaces may for example activate both interfaces (if present), or alternatively indicate the available connection options to the user and wait for user feedback. Also, it is conceivable that a device is provided with internal preset priority parameters indicating a priority order in which to activate interfaces, or at least one preferred interface without any parameters for the remaining interfaces. That is, when connection availability for a first type of interface and a second type of interface is detected, the device may be set to always prefer activation of the second interface. When a priority parameter for each interface is received in the connectivity signal, the device may be able to follow the priority indication and e.g. activate only the interface having the highest priority parameter. In other embodiments or situations, the receiving device may decide to override the priority parameters, e.g. when a specific application requires a specific interface (or its features) for communication. Yet another option is that a device may be set not to automatically connect to any interface on reception of a connectivity signal, but to display all connection options to a user via a display or similar means, and the user may then choose his preferred interface (potentially with a proposal for a connection made by the device).

The transmission format used for broadcasting connectivity parameters and information may be implemented in various ways. A common system implemented in FM radio is the radio data system (RDS). This technology allows transmitting certain supplement data with an audio data stream, such as a name or identifier of the current radio station, a current time signal, text information to be displayed such as a song title or contact phone numbers, traffic information, and many more. Certain codes may be assigned to specific information, such as unambiguous codes for each radio station, for easier communication. These signals are generally directed to use with high power commercial radio stations. The additional data is transmitted on a subcarrier of the actual carrier frequency as a modulation, in case of RDS at a 57 kHz subcarrier. In the radio data system or radio broadcast data system (RBDS) protocol, information is transmitted in a group or block structure. Data groups are transmitted at a rate of approximately 11 groups per second. Each data group is made up of four blocks of information, with each block containing 26 bits. Those 26 bits include a 16 bit data portion and a 10 bit check word, or cyclic redundancy check (CRC), portion. Several group types are defined in the protocol, which types specify different configurations of data sent to a receiver. Further details of the well-known RDS system, which is a standard originally developed by the European Broadcasting Union, may be found in "RDS Universal Encoder Communication Protocol", UECP version 5.1, European Broadcasting Union/RDS Forum, or also known as standard IEC 62106 (December 1999) from the International Electrotechnical Commission; and details of the similar US system RBDS approved by the National Radio Systems Committee may be found in "United States RBDS Standard", draft 2.0, August 1997. It shall be understood that the various embodiments of the invention are not limited to any of these standards or versions of same in particular, and that comparable systems may exist which allow similar implementations of the described features. Thus, RDS is one example of a data transmission structure which may be used for broadcasting connectivity signals via FM radio transmissions. In some exemplary embodiments of the invention, the RDS Open Data Application (ODA) functionality may be used for transmitting connectivity data. ODA is a RDS feature providing flexibility for additional applications. Generally, the ODA feature allows for flexibly including additional functions which are not originally implemented in the RDS standard. It shall be noted that all "signals" and "transmissions" via FM radio mentioned in this description may (as an example) be implemented according to the RDS and similar protocols, that is in a group and block structure of bits. In the current standard version, type 3A groups are reserved for application identification with ODA, i.e. for indicating the specific type of application for this and following signal groups. Examples for transmitting connectivity signals using an ODA application identification group and optionally further groups are given in Figure 4a and 4b. In the present case, the application is signalling of connectivity options, such that the application identification may allow a receiving device both to recognize the signal on a frequency and choose the correct decoding. A group 401 of this type may be transmitted first and may also include up to 16 data bits, and further ODA groups 402 may then follow if necessary. In these type 3 A groups (that is, the identification signals 401), a first portion of 16 bits within the first block 410 is assigned to a program identification code 411, which may in case of the inventive embodiments be used as a device identifier, as there is no commercial radio program to be identified. A device identifier may be useful in case of several devices within each other's coverage range, such that each device is able to clearly determine the connection capabilities of all other devices separately. In other embodiments, a device identifier may be encoded in the message bit section 431 of this signal group 401. The only prerequisite is that the receiving devices are able to determine the meaning of the signal parts, e.g. by using a predefined protocol. After this identifier 411, a checkword 412 for example of 10 bits may follow, as is the case for each data block in RDS. In the second code block 420 of another 16 bits, four bits are assigned to the group type code 421 of the current group itself, which is 0011 for the type 3 groups, plus an additional bit 422 indicating the group type version (0 for 3A, 1 for 3B). The next bit 423 is usually used for a traffic program code, a single bit indicating whether traffic announcements are transmitted on a commercial station. This bit 423 may be set to 0 for the connectivity signal, indicating that the transmission does not carry or does not refer to traffic information. The next five bits 424 are assigned to program type codes in the RDS standard, which are predefined codes for usually indicating the kind of program playing on a radio station, such as "rock" or "news". The program type 424 may also be used for display at a receiver device. These bits may be set to zero if no such indication is required; alternatively, it is conceivable in some embodiments to indicate something as "connection signal" in this field if supported, and such information might even be displayed on the receiving device. The following four bits 425 are used for defining the application group type code, which indicates which group type is to be used for the transmissions of the connectivity signals. This applies if further groups are necessary for transmitting all parameters; if 16 bits are sufficient, the application identification type 3 A group 401 may be the only group transmitted. That is, the application group type code 425 is indicated according to the selected group type for the subsequently transmitted connectivity signal groups 402. Several group types are allowable in ODA applications, as mentioned in the standard and not detailed here. Another 10-bit checkword 426 for the second block follows.

The next block 430 with its associated checkword 432 is assigned to message bits. Finally, in the last block 440, a 16-bit application identification code 441 is transmitted, determining the software handler a receiver needs to use. Application identification codes indicate applications as specified in the ODA directory, where all applications for ODA should be registered. With the subsequent checkword 442 for the fourth block, the group (identification signal 401) is completed.

In a simple implementation, the 16 message bits 431 of the application identification group may be sufficient for transmitting the connectivity signal. In this case (shown in Figure 4a), the application group type code 425 may be set to 00000, indicating that no data is carried in an associated group. The 16 bits may for example be used for broadcasting information regarding four different interfaces a, b, c and d. If the interface types are predefined for the given protocol, there is no need to label or identify the parameters, since the bit position will clearly define the interface the parameter is associated with. As one example, the first bits a_h b), C₁, di of each four bit portion may each indicate the presence of the associated wireless interface (e.g. WLAN, Bluetooth, wireless USB, and high-speed Bluetooth). The second bits a₂, b₂, C₂, d₂ of each portion may be used for indicating the current availability of the interface, as already mentioned above generally. A third and fourth bit a₃/a₄, b₃/b₄, c₃/c₄, d₃/d₄ may then be used for indicating a 2-bit priority parameter, giving a priority order in which the interfaces shall be used (with e.g. 00 indicating lowest priority, and 11 indicating highest priority or preferred interface). Another simple exemplary assignment is to use only two bit flags per interface, indicating e.g. presence and current availability, thus allowing to transmit basic parameters for up to eight interfaces within the single application identification signal. On the other hand, when only two interfaces need to be announced, 8 bits of information are available for each of these, allowing also more complex parameters or additional capability parameters.

If more data needs to be transmitted, these 16 bits 431 within the identification group may alternatively be used for announcing further information on the following transmissions, e.g. the actual number of interfaces and corresponding parameter fields which will be transmitted in further, subsequently transmitted groups 402. This may allow flexible connectivity broadcasts without defining beforehand as a protocol which or how many interfaces can be announced. Again, an exemplary case shall be given, illustrated by the signal structure in Figure 4b. In the 16-bit portion, a binary number 452 of e.g. 4 bits may be used for announcing the number of interfaces, allowing the receiving device to detect when all information has been received completely. In the remaining 12 bits 454, for example a version number may be provided for ensuring that both devices work with the same protocol version for connectivity features, so that definitions of e.g. interface identifiers and other agreements are clearly set. Also, if the program identifier 41 1 is not used as a device identifier, some or all of the 16 bits might be use for signalling a device identifier. It will be understood that any parameter, code, or value useful for a connectivity announcement may be included in these bits.

Following the application identification group 401 (for the case of more data to be transmitted), one or more groups 402 of a type as defined in the previous application group type field are transmitted. Generally, up to 37 message bits are available for data in type A groups, and up to 21 bits in type B groups. The program identification code in the first 16 bits of each group, used as a device identifier according to example embodiments of the invention, will allow a receiving device to clearly associated all received information to a specific device. The message bits may be assigned as suitable; an example using a type 1 IA group is given in Figure 4b. Considering four different interfaces or transmission protocols available, 8 bits may be assigned for each interface, and 5 bits 427 may be used for other purposes, e.g. indicating once more the number of interfaces, or a version number. Of the 8 bits per interface, three bits (ei to e₃, fi to f₃, g] to g₃, h] to h₃) may for example be used as an interface identifier. The corresponding interfaces assigned to each identifier may then be predefined and known to all supporting devices. With the interface identifier, the receiving device is able to determine which one of a larger number of potential interfaces is announced, and the parameters following the respective identifier are associated with this interface. This leaves 5 bits (e₄ to e₈, and so on) per interface of parameters, which may used e.g. for indicating the current availability of the interface, support for different operating modes (either as single bit flags for each operating mode, or as binary codes using multiple bits, with each operating mode being associated with a predefined code), and priority or preference parameters. One alternative is to use specific parameters as those described below in connection with Figure 4c, but any other parameters may be included here in the signal group 402 as well.

In yet another embodiment, illustrated in Figure 4c, two blocks of data having 26 bits each may be used for transmitting a connectivity signal. That is, instead of a signal group strictly according to RDS standard, merely 52 bits corresponding to two RDS blocks in length are used and assigned according to separate rules particularly for the connectivity signalling feature. As an example, the first 3 bits 470 may be assigned to a version number field, followed by the actual parameter information 480 of 30 bit. The 30 bit connection parameter element 480 may include a device identifier 482 of one octet (8 bits), 10 bits for a WLAN information element 484 and 12 bits for a Bluetooth and WUSB information element 486. All remaining bits 488 may be reserved for future use, e.g. for information on further interfaces, for setup parameters or for similar purposes.

The version number field 470 of this example may be three bits in length and present an integer version number of the connectivity signal application. For example, the bit assignment as described in the following paragraph may correspond to a version number of 0, and different bit assignments may then be indicated by other version numbers. The device identifier (transmitter identifier) 482 may be one octet in length and represent a random number for identifying the device transmitting the connectivity signal. Following this identifier, a WLAN capability and availability information part 484 may be encoded in 10 bits. The first 5 bits 491 may be used for information with regard to a 2.4 GHz WLAN radio connection, and the latter 5 bits 492 may then be used for information with regard to a 5 GHz WLAN radio connection. The WLAN information may include parameters on the capabilities for ad hoc mode, access point mode, mesh mode, an availability parameter, and a preference parameter. All these parameters may be implemented as binary flags. That is, the first bit is set to 1 if the broadcasting device supports ad hoc mode connections for 2.4 GHz WLAN (e.g. IBSS mode as specified in IEEE 802.1 1 standard family), and to 0 if it does not support this mode. The second bit is implemented similarly for access point mode or infrastructure operation mode, and the third bit will then indicate the capability for operating in mesh mode. The fourth bit is set to zero if the connection is not available for usage, e.g. because the device does not include this interface, the interface is deactivated, or it is already in full use by another application. Finally, the fifth bit indicates whether this specific radio connection is preferred for pairing when several interfaces are present. The following 5 bits are implemented similarly for the 5 GHz WLAN.

Further, the 12 bits (486) assigned to Bluetooth and WUSB in the present example may carry parameters for a standard Bluetooth connection (portion 493), a high-speed Bluetooth connection (based on WiMedia UWB) (portion 494), Wireless USB (WUSB) (portion (495), and a Bluetooth Low Energy connection (portion 496). Of course, other interfaces may be defined in other implementations. For each interface, 3 bits are assigned. The first bit is a capability bit indicating whether the device is capable of operating with this standard, i.e. whether the interface is present in the terminal. The second bit is a current availability bit, indicating whether the interface is currently available, i.e. not reserved or not usable otherwise. The third bit is again a preference bit indicating whether this specific interface/standard is the preferred connection. It will be understood that usually only one of the defined interfaces should be provided with a preference bit of 1 to avoid ambiguities. Again, all bits may be used as binary flags, with 1 indicating support or availability for the specified feature and 0 indicating non-support.

It should be noted that beside the above example embodiments of format of the transmitted connectivity parameters any other types or formats for the transmission might be used. One example of another format is the transmission based on extensible Markup Language (XML).

It should be noted that at least two different transmission principles are conceivable for the connectivity signals in the example case of FM transmission. One is embedding the connectivity information into RDS messages which are transmitted as part of a normal low power FM transmission. This may for example be applied when the broadcasting device also uses FM short range transmissions for other purposes, such as audio streaming to other devices. In this case, the connectivity information is simply one of several applications which may be carried on top of the transmission. The connectivity signal and other RDS information (e.g., played song and artist for a media playback process) may alternate in any suitable way.

A second option is that one frequency channel is only used for connectivity signals by one or more terminals. The channel is used only for transmitting short RDS data sequences, and there is not necessarily any further transmission such as audio on the channel. The transmitter of the broadcasting device may in this case apply a random channel access principle (CSMA/CA) for the connectivity signals, selecting random transmission opportunities for the signal provided as RDS information. The channel access may use time slots having a duration of e.g. 86.7 ms, which is the duration of one RDS group of four blocks. A random integer number of slots (e.g. between 2 and 8) may be specified during which the channel needs to be idle, i.e. no pilot tone is to be received in the channel, before RDS data may be transmitted. When the channel has been idle for a duration of one slot, the random counter number is decreased by one, and as soon as the value equals zero the transmitter may start broadcasting its RDS data. The broadcast RDS signal may be repeated for a more robust transmission, and/or may also be repeated periodically as already described above. Terminals which are currently not transmitting any information may, if provided with a receiver as well, receive the connectivity signal from other devices, allowing a large number of devices within the same area to exchange their local wireless connectivity information using a single unidirectional channel.

As the data on a FM radio channel or other unidirectional radio transmissions is broadcast over the coverage range of the broadcasting transmitter, all devices located within this area will be able to receive the transmitted signals. This may allow informing several devices about connection capabilities and parameters with a single, brief transmission. Furthermore, several devices may broadcast their connection capabilities using this technology, and a single device may therefore receive parameters from different devices and may then decide which connections to make. Using device identifiers with each connectivity signal, as already described above, will enable a receiving device to distinguish the separate signals. Also, it has been described above how a single frequency channel may be shared by multiple transmitting devices defining idle periods before a transmission may be started. When several receivers are present in a device, it is also conceivable that a receiving device may receive connectivity signals from different devices on different frequencies. Detecting the correct frequencies for each receiver may be performed as detailed above for a single receiver.

The forming of a signal from parameters on the end of the broadcasting device, the frequency selection and/or the overall control of the transmission may be controlled by a central device processor. Such a processor may also be responsible for further functionalities, such as a central processing unit in a portable computer or communication apparatus. Alternatively, some or all of the broadcast related processes may be performed by a separate controller or processing unit. A separate controller may be embedded within a separate interface module, including the respective wireless interfaces. Also, some of the processes and functionalities described above may be hardware or software implemented. For example, the frequency scanning may be based on a software control of a short range unidirectional transmission or reception apparatus.

Although exemplary embodiments of the present invention have been described, these should not be construed to limit the scope of the appended claims. Those skilled in the art will understand that various modifications may be made to the described embodiments and that numerous other configurations or combinations of any of the embodiments are capable of achieving this same result. Moreover, to those skilled in the various arts, the invention itself will suggest solutions to other tasks and adaptations for other applications. It is the applicant's intention to cover by claims all such uses of the invention and those changes and modifications which could be made to the embodiments of the invention herein chosen for the purpose of disclosure without departing from the spirit and scope of the invention.

Claims

1. A method comprising determining at least one or more connectivity parameters of at least one bidirectional wireless interface; forming a connectivity signal suitable for a unidirectional radio transmission including said connectivity parameters; selecting at least one transmission parameter; and broadcasting said signal via the unidirectional radio transmission interface using said selected transmission parameter.

2. The method of claim 1, wherein said unidirectional radio transmission is a frequency modulated radio transmission.

3. The method of claim 1 or 2, wherein said connectivity parameters include a current availability of said at least one bidirectional wireless interface.

4. The method of any previous claim, wherein said connectivity parameters include supported operating modes of said at least one bidirectional wireless interface.

5. The method of any previous claim, wherein said connectivity parameters include a priority parameter for said at least one bidirectional wireless interface.

6. The method of any previous claim, said selecting of a least one transmission parameter comprising the selection of a least one transmission frequency.

7. The method of claim 6, said selecting of a transmission frequency further comprising scanning through a predefined range of frequencies, and checking whether one of said frequencies is available for use.

8. The method of any previous claim, further comprising repeating said determination of connectivity parameters after a predefined period of time, checking whether said connectivity parameters have changed; and if said connectivity parameters have changed, forming and transmitting another connectivity signal from said repeated determination of connectivity parameters.

9. A method comprising receiving a broadcast connectivity signal at a unidirectional radio interface; extracting from said connectivity signal at least one connectivity parameter associated with at least one bidirectional wireless connection option; and activating at least one bidirectional wireless interface in accordance with said connectivity parameters.

10. The method of claim 9, wherein said unidirectional radio interface is a frequency modulated radio interface.

11. The method of claim 9 or 10, further comprising storing said extracted at least one connectivity parameter.

12. The method of any of claims 9 to 11, further comprising activating said at least one bidirectional wireless interface when a connection is required by an application.

13. The method of any of claims 9 to 12, further comprising activating said at least one bidirectional wireless interface when a connection is requested by a user.

14. The method of any of claims 11 to 13, further comprising retrieving at least one of said stored at least one connectivity parameter.

15. The method of any of claims 9 to 14, further comprising checking whether a received signal is a connectivity signal.

16. The method of claim 15, wherein said check includes matching at least a portion of said received signal against one or more signal sequences.

17. The method of any of claims 7 to 13, further comprising scanning a range of radio frequencies; and terminating said scanning upon detecting a predefined signal sequence on one of said frequencies.

18. The method of any of claims 7 to 14, wherein said connectivity signal includes a parameter indicating current availability of an interface at a remote apparatus.

19. The method of any of claims 7 to 15, wherein said connectivity signal includes at least one parameter indicating supported operating modes of an interface at a remote apparatus.

20. The method of any of claims 7 to 16, wherein said connectivity signal includes a priority parameter indicating preference settings for at least one interface.

21. The method of claim 17, further comprising selecting an interface for activation based on said priority parameters.

22. An apparatus comprising at least one unidirectional radio transmitter; at least one bidirectional wireless interface; wherein said apparatus is configured to broadcast connectivity parameters associated with said at least one bidirectional wireless interface via said unidirectional radio transmitter.

23. The apparatus of claim 22, wherein the said unidirectional radio transmitter is a frequency modulated transmitter.

24. The apparatus of claim 22 or 23, wherein said apparatus is further configured to determine connectivity parameters of said at least one bidirectional wireless interface.

25. The apparatus of any of claims 22 to 24, said apparatus further configured to detecting a frequency available for broadcasting said connectivity parameters.

26. The apparatus of claim 23, wherein said apparatus is configured to detect said frequency by scanning through a predefined range of frequencies.

27. An apparatus comprising at least one unidirectional radio receiver; at least one bidirectional wireless interface; wherein said apparatus is configured to activate one or more of said at least one bidirectional wireless interfaces based on a connectivity signal received via said unidirectional radio receiver.

28. The apparatus of claim 27, wherein the said unidirectional receiver is a frequency modulated receiver.

29. The apparatus of claim 27 or 28, said apparatus being configured to extract connectivity parameters included in said connectivity signal.

30. The apparatus of claim 29 , further including a memory element, and wherein said apparatus is configured to store said extracted connectivity parameters.

31. The apparatus of any of claims 27 to 30, including at least two bidirectional wireless interfaces, and wherein said apparatus is configured to select one of said bidirectional wireless interfaces for activation based on said extracted connectivity parameters.

32. The apparatus of any of claims 27 to 31 , wherein said apparatus is configured to detect a frequency carrying said connectivity signal.

33. An apparatus comprising means for receiving a broadcast connectivity signal; means for extracting from said connectivity signal at least one connectivity parameter associated with at least one bidirectional wireless connection option; and means for activating at least one wireless connection means in accordance with said connectivity parameters.

34. An apparatus comprising means for determining of at least one or more connectivity parameters of at least one bidirectional wireless interface; means for forming a connectivity signal suitable for a unidirectional radio transmission including said connectivity parameters; means for selecting at least one transmission parameter; and means for broadcasting said connectivity signal using said selected transmission parameter.

35. A computer program comprising code sections which, when executed, perform the following steps: determining at least one or more connectivity parameters of at least one bidirectional wireless interface; forming a connectivity signal suitable for a unidirectional radio transmission including said connectivity parameters; selecting at least one transmission parameter; and broadcasting said connectivity signal via the unidirectional radio transmission interface using said selected transmission parameter.

36. A computer program comprising code sections which, when executed, perform the following steps: receiving a broadcast connectivity signal at a unidirectional radio interface; extracting from said connectivity signal at least one connectivity parameter associated with at least one bidirectional wireless connection option; and activating at least one bidirectional wireless interface in accordance with said connectivity parameters.