Methods, apparatuses and computer programs for inter-cluster connection in a wireless personal area network

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DESCRIPTION

Procedures, devices and computer programs for a connection between clusters in a wireless personal area network

FIELD OF THE INVENTION

The present invention relates to a wireless personal area network (WPAN).

DESCRIPTION OF THE RELATED TECHNIQUE

Recently, attempts have been made to increase cooperation between home devices. In line with this increased demand, various wireless technologies have been developed, including, for example, Bluetooth and similar technologies, which typically allow communication within a radius of approximately 10 meters; In other words, a very small range. These short-range private networks are commonly called Wireless Personal Area Networks (WPAN).

The goal of a WPAN is to facilitate seamless operation between home or business devices and systems, and each device on a WPAN will be able to connect to any other device on the same WPAN, as long as they are within physical range of each other. In homes, WPANs provide wireless connections for alarms, electrical appliances, and entertainment systems.

An example of a suitable network protocol for a WPAN is the IEEE 802.15 standard, which includes, for example, Bluetooth (IEEE 802.15.1), which is suitable for low-power digital radios, such as wireless headsets that they connect to cell phones via short-range radio. Another example is the ZigBee specification (IEEE 802.15.4), which is aimed at building automation. ZigBee technology is intended to be simpler and cheaper than, for example, Bluetooth, and is therefore intended for radio frequency (RF) applications that require low data transfer rates, long battery life and a connection in secure network. However, a problem with WPAN is that the current implementation of the network topology is provided as non-cooperative networks based on subordinate devices, where each of the networks can potentially exist on a different channel frequency and therefore will do make communication through different networks more complicated.

Document EP 1 528 717 tries to solve this by providing an improvement in the cooperation between different wireless devices of a WPAN. A broadcast procedure is provided to troubleshoot when a device recognizes that at least two different WPANs are communicating on the same channel frequency. The conflict is detected and a coordinator device, ie a coordinator, broadcasts a coordinator realignment command to the devices, ordering them to change the currently used channel to another channel. The realignment command comprises changing information in a payload field of the synchronous signal and inserting a predetermined identification bit in the reserved bit of a frame control field of the synchronous signal.

However, although EP 1 528 717 proposes a partial solution to the problem of conflicting WPANs communicating on the same channel frequency, it does not take into account the initialization phase in which a plurality of coordinators are arranged to communicate with each other. , nor the process that allows coordinators to switch to an optimal channel frequency. Instead, EP 1 528 717 relies only on the prior art subordinate device-based non-cooperative network topology, which introduces additional network traffic due to latency issues.

Document US 2007/076596 discloses the implementation of an imperceptible blind channel change (BSCC) when at least one device of a plurality of wireless communication devices is stuck on a current communication channel. A first wireless communication device transmits a BSCC message on the current communication channel to a second wireless communication device, which message includes information regarding a communication channel selected from a plurality of available communication channels to which the first communication device wireless communication will switch then, and a period of time in which the first wireless communication device will be transmitting on the selected communication channel. The first wireless communication device switches to the selected communication channel. The second wireless communication device receives the BSCC message and switches to the selected communication channel. The first and second wireless communication devices resume normal wireless communications.

SUMMARY OF THE INVENTION

There is a need for a WPAN that takes into account the initialization phase when a plurality of coordinators are arranged to communicate with each other, and that also provides lower latency, offering higher bandwidth and greater energy efficiency. The invention is defined by the independent claims. The dependent claims define advantageous embodiments.

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According to one aspect of the invention, the above object is achieved by means of a method for a first coordinator operating on a first channel frequency in a wireless personal area network (WPAN), the WPAN further comprising a second coordinator operating on a second channel frequency, the method comprising the steps of transmitting a message on a plurality of channel frequencies, including the second channel frequency, requesting the second coordinator to switch from the second channel frequency to the first channel frequency, and establishing communications with the second coordinator using the first channel frequency.

According to the present invention, by coordinator is meant a wireless communication device that can configure a WPAN, for example, generally, a controllable or controlled device that is normally a stationary device connected to the electrical network. Thus, according to the present invention, two of these devices are arranged to "pair" with each other during an initialization phase and to switch to the channel frequency of the coordinator that initiated the communication. On the contrary, according to the prior art, the first coordinator will adopt the channel frequency of the second coordinator, thus causing the problem of higher latency and additional network traffic, since the coordinators will have to switch between their preferred channel frequencies.

Furthermore, the expression "message" should be understood as a signal that comprises, at least partially, a defined content intended to request the second coordinator to switch to the channel frequency of the first coordinator. Furthermore, the message can be any type of message, for example a specific initialization message (or initialization signal), or be included in a general broadcast message.

Advantages of the present invention include the fact that priority-based mechanisms are not needed. This is because, as mentioned above, the coordinator who initiates the communication decides the channel frequency used, that is, each coordinator who establishes a communication can make the coordinator with whom he wishes to communicate switch to his frequency. Another advantage of the present invention is that it is possible to easily transmit a broadcast message and implement a repeater solution.

However, the procedure is not only useful during the initialization phase in which a WPAN is configured, it is also useful when additional devices are introduced into the WPAN. Consequently, in case the WPAn preferably comprises a third additional coordinator, the third coordinator operates on a third channel frequency, and both the first and second coordinators are preferably adapted to carry out the steps of monitoring independently of each other. transmit a message on a plurality of channel frequencies, including the third channel frequency, requesting the third coordinator to switch from the third channel frequency to the first channel frequency, and establishing communications with the third coordinator using the first channel frequency. That is, both the first and second coordinators can independently cause the third coordinator to switch to the channel frequency of the first coordinator, thus allowing the possibility of establishing communications on a single channel frequency. As described above, this increases the available bandwidth and optimizes the power efficiency of the WPAN.

Furthermore, the method according to the present invention is not limited only to the first coordinator. Consequently, corresponding procedural steps can therefore be executed in the second (or third) coordinator comprised in the WPAN, where the second coordinator operates on a second channel frequency and the WPAN further comprises a first coordinator that operates on a first channel frequency. channel. From the perspective of the second (or third) coordinator, the method therefore comprises the steps of receiving a message from the first coordinator, receiving a request from the first coordinator to go from the second channel frequency to the first channel frequency, and establish communications with the first coordinator using the first channel frequency. Obviously, these steps can also be executed by the first coordinator if, for example, the second coordinator initiates the communication.

According to a preferred embodiment of the invention, the request to go to the first channel frequency is provided as a separate message (or signal) when the first coordinator receives a response from the second coordinator.

According to another preferred embodiment of the invention, the request to go to the first channel frequency is included in the message. That is, preferably, the at least one of the messages is a packet type message that comprises a header that contains information related to the channel frequency of the first coordinator, for example that includes at least two specific bits of channel frequency in the header. . With two channel frequency bits, a maximum of four different channel frequencies can be communicated. However, one or more than two bits may of course be dedicated to information related to the channel frequency. Therefore, the channel frequency preferred by the first coordinator will be communicated (eg included) in the headend, where the headend is preferably a headend, although it may possibly be any type of headend. Other common header types are PHY headers, MAC headers, transport headers, etc.

Furthermore, the step of transmitting a message on a plurality of channel frequencies preferably comprises the use of frequency agility, or also commonly referred to as dynamic channel / frequency selection. Frequency agility, or the use of the frequency agility mechanism as will be described in greater detail later, includes periodically changing the transmission frequency or switching between a plurality of predefined channel frequencies. The use of frequency agility is also used to avoid interference from a source of

ES 2 532 014 T3 known interferences or other source of signals, for example conflicting WPAN in the vicinity of the coordinator of interest. In a home, for example, multiple types of wireless networks are likely to compete for the same frequency bands, as well as unintended interference from electrical appliances. Therefore, the reallocation capacity within the spectrum will be an important factor in the success of the network.

Preferably, the communication between the control unit and the device is provided by radio frequency (RF) communication and, more preferably, is RF communication based on at least one of the IEEE 802.15.3 and IEeE 802.15.4 standards. Generally, when an IEEE 802.15.3 or IEEE 802.15.4 WPAN is implemented, the basic network topology will be in the form of a basic star, where a WPAN can consist of interconnected stars. Also, depending on the network technology used, there will be a different number of channel frequencies available. For example, when using IEEE 802.15.4 there are a total of 16 channel frequencies available in the United States, but only a subset of these channels will be used for frequency agility as otherwise the latency will become very big enough to handle. Therefore, a practical number of channel frequencies to be used with IEEE 802.15.4 technology is three or four.

According to a further aspect of the invention, a first coordinator is provided to be used in a WPAN, the first coordinator operating on a first channel frequency and comprising means for transmitting a message on a plurality of channel frequencies, including a second channel frequency. channel, means for requesting a second coordinator to switch from the second channel frequency to the first channel frequency and means for establishing communications with the second coordinator using the first channel frequency.

This aspect of the invention provides advantages similar to those of the above-described method including, for example, the fact that a priority-based mechanism is not needed and that each coordinator who establishes communication can cause the coordinator with whom he wishes to communicate to change. at your frequency. Another advantage of the present invention is that it is possible to easily transmit a broadcast message and implement a repeater solution.

The coordinator is preferably a consumer electronic device (CED), such as at least one of a television (TV), a digital versatile disc player (DVD), a home theater system (HTS), and a wireless remote control. (RC).

Furthermore, these and other objects of the present invention may be achieved through a computer program adapted to run on a coordinator (eg, a first, second, or third coordinator) according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described in greater detail, with reference to the accompanying drawings showing presently preferred embodiments of the invention, in which:

Fig. 1 is a WPAN comprising a plurality of coordinators operating in accordance with a prior art network topology configuration;

Fig. 2 is a WPAN similar to Fig. 1, operating according to a network topology configuration according to the present invention; and Fig. 3 is a timing diagram illustrating an example of the stepwise transition to a single / optimal channel frequency in accordance with the present invention.

DETAILED DESCRIPTION OF CURRENTLY PREFERRED EMBODIMENTS

The present invention will now be described in greater detail with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. However, this invention can be made in many different ways and should not be construed as being limited to the embodiments described herein; rather, these embodiments are provided to provide a thorough and comprehensive description, and convey the scope of the invention in its entirety to those skilled in the art.

Referring now to the drawings, and to Figure 1 in particular, a prior art WPAN 100 is shown comprising a plurality of coordinators or coordinator-based devices 102, 104, and 106, each displaying a WPAN ID. different (or other suitable network identifier) ​​and configured to communicate on a different channel frequency, for example a first f1, a second f2 and a third f3 channel frequency, respectively, where the coordinators 102, 104 and 106 are configured as a non-cooperative network based on subordinate devices.

As mentioned above, the coordinators are preferably consumer electronic devices (CED) such as, for example, a television (TV), a digital versatile disc player (DVD) and a home theater system (HTS). According to the prior art WPAN 100 shown in Figure 1, the coordinator-based device initiating communication will use the WPAN ID and channel frequency of the device with which it wants

ES 2 532 014 T3 communicate, instead of its own WPAN ID and channel frequency, and therefore, if one of the coordinators 102, 104 or 106 wants to control one of the other devices, it will have to switch from a frequency of channel to the next.

If, during operation, prior art WPAN 100 coordinator 102 wishes to communicate with coordinator 104, it will have to switch to coordinator 104 channel frequency, that is, switch from the first channel frequency f1 to the second channel frequency f2. At that time, the coordinator 102 will not be available to the coordinator 106 since, for a certain amount of time, the coordinator 102 will not be able to receive communications from the coordinator 106. That is, the coordinator 102 will not attend the communications coming from the coordinator 106 . Due to the subordinate device-based non-cooperative network topology used by the prior art WPAN 100, there will be increased utilization of the frequency agility mechanism, increasing latency and causing additional network traffic. Also, if coordinator 102 wants to communicate with coordinator 106, it will have to switch to coordinator 106's channel frequency (i.e. third channel frequency f3) and will not be able to communicate with coordinator 104 at the same time, i.e. similarly, coordinator 102 will not be able to handle communications from coordinator 104. Consequently, all devices 102, 104, and 106 will communicate with each other on different channel frequencies.

Therefore, the prior art network topology used by the WPAN 100 does not provide any mechanism to switch to the single channel frequency, and the coordinator 102 can only resort to a power detection (ED) scan and information of Possibly erroneous checksum (CRC) to trigger a channel frequency change. Furthermore, broadcast messages will not be possible and / or useful, and a repeater implementation (ie, a device having repeater functionality) will not work in the non-cooperative network described above.

In accordance with the present invention, an implementation is illustrated in Figure 2, in which a WPAN 200 similar to the WPAN 100 of Figure 1 is shown. However, the WPAN 200 of Figure 2, in addition to the three coordinators 202, 204 and 206, comprises a wireless multifunction remote control (M_RC) 208 that is provided to control the functionality of the different coordinators; the multifunction remote control itself will not normally have the capabilities of a coordinator, but it is possible to offer a multifunction remote that has the capabilities of a coordinator. A non-coordinator-based device will act according to the prior art. As described above, the coordinators are preferably consumer electronic devices (CED) such as, for example, a television (TV), a digital versatile disc player (DVD) and a home theater system (HTS), or any other similar device used in a home environment. However, it is understood that other present and future devices suitable for use in connection with a WPAN may be considered with respect to the present invention.

Like WPAN 100, coordinators 202, 204, and 206 (for example, first, second, and third coordinator, respectively) have a different WPAN ID, so each resides on a different channel frequency, for example a first f1, a second f2 and a third f3 channel frequency, respectively. Also, similar to the WPAN 100 of Figure 1, if a coordinator, for example the first coordinator 202, wishes to communicate with another coordinator, for example the second coordinator 204, the first coordinator 202 will use the frequency agility mechanism to find coordinator 204 (eg, by subsequently scanning different channel frequencies, such as the first f1, the second f2, and the third f3 channel frequency). When the first coordinator 202 has found the second coordinator 204, it communicates the channel frequency on which it is operating and, after receiving this message, the coordinator 204 sends an acknowledgment on the channel on which the message was received and then switches to the frequency channel of the coordinator that initiated the communication (ie, coordinator 202). However, the advantage of the present invention is most notable when additional coordinators are provided that communicate with each other.

For example, as just described, if the first coordinator 202 wishes to communicate with the second coordinator 204, it will request the second coordinator 204 to switch to the preferred channel frequency of the coordinator 202, that is, to the first channel frequency f1. Later, if the first coordinator 202 wishes to communicate with the third coordinator 206 (or if the second coordinator 204 wishes to communicate with the third coordinator 206) it will cause the coordinator 206 to also switch to the channel frequency of the coordinator 202, that is, to switch from the third channel frequency f3 to the first channel frequency f1. Also, if the wireless multifunction remote control 208 is in communication with the different coordinators 202, 204 and 206, the multifunction remote control 208 will switch to the channel frequency of the coordinator that initiated the initial communication, which in this case is the first coordinator 202 Consequently, all devices 202, 204, 206, and 208 will communicate on the channel frequency (ie, the first channel frequency f1) of the first coordinator 202.

However, if a source of interference is introduced in the vicinity of the WPAN 200 and the currently operating channel frequency is affected, any one of the coordinators 202, 204 or 206 can individually decide to switch to a different channel frequency. , without informing the other coordinators. Since the coordinators are supposed to operate in the same environment, it is to be expected that the other coordinators will also detect the source of interference and switch individually. If some of the devices switch and others do not, then the same mechanism provided above will be used again to facilitate communications between coordinator-based and non-coordinator-based devices. Another approach may be to broadcast a channel change message when changing channels.

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Reference is now made to Figure 3, which illustrates a timing diagram of coordinators 202, 204, and 206, and remote control 208, switching from individual channel frequencies, i.e., the first f1, the second f2 and the third channel frequency f3, at a unique channel frequency and optimized for communication between devices 202, 204, 206 and 208.

In the timing chart, the process begins when the first coordinator 202, for example a TV, initiates a communication with a second coordinator 204, for example a DVD. TV 202 uses frequency agility to find DVD 204. A first, second, and third position 302, 304, and 306 mark when TV 202 transmits sequentially on a first f1, a second f2, and a third f3 channel frequency. in your search for DVD 204.

At position 308, TV 202 finds DVD 204 and communicates its operating (or preferred) channel frequency, that is, first channel frequency f1, and DVD 204 switches to TV channel frequency 202, ie ie the first channel frequency f1.

Subsequently, at position 310, wireless multi-function remote control 208 initiates communications with DVD 204. Also multi-function remote control 208 uses frequency agility to find DVD 204 (indicated by positions 310, 312, and 314) . Then, the multi-function remote control 208, at position 316, adopts the channel frequency of the TV 202, that is, the first channel frequency f1, since the DVD 204 has inherited the channel frequency (that is, the frequency of channel f1) of TV 202.

At location 318, DVD 204 initiates communications with the third coordinator such as, for example, an HTS 206. Again, DVD 204 uses frequency agility to find HTS 206 (indicated by locations 318, 320 and 322). The HTS 206 adopts, at position 324, the channel frequency of DVD 204 and switches to the first channel frequency f1.

At location 326, TV 202 initiates communications with HTS 206. Again, TV 202 uses frequency agility to find HTS 206 (indicated by locations 326, 328, and 330). When the TV 202 finds the HTS 206 it communicates its channel frequency, that is, the first channel frequency f1, to the HTS 206 at position 332, and the HTS 206 then switches to the channel frequency of the TV 202, that is, the first channel frequency f1. In this example, the HTS is already in the f1 of the TV through the stages of the previous paragraph. Therefore, this specific sequence is not necessary.

In addition, at position 334, the multi-function remote control 208 tries to communicate with the HTS 206. Also, the multi-function remote control 208 will use the frequency agility mechanism to find (as indicated by positions 334, 336, and 338) the channel frequency on which the HTS 206 is communicating. Then, at position 340, the multifunction remote control 208 will adopt the first channel frequency f1 for communication with the HTS 206. Thus, at this point, all devices 202, 204, 206, and 208 will have switched to the TV channel frequency 202 (i.e. the first channel frequency f1) and thus a single transmit frequency will be used. and optimized for communications between devices. In fact, the remote will start communicating on the channel frequency the HTS was originally on. The remote will have to use a frequency agility reacquisition mechanism to find the HTS and therefore adopt the new frequency. This applies only to non-coordinator-based devices, such as remote controls.

Furthermore, those skilled in the art realize that the present invention is in no way limited to the preferred embodiments described above. Rather, it is understood by those skilled in the art that many modifications and variations are possible within the scope of the appended claims. For example, the number of coordinators and non-coordinators is variable and can be increased or decreased as needed. Additionally, the frequency agility mechanism can be made more efficient by storing the RF channel on which another device is expected to operate. When a device wants to communicate with another device, it first looks at this information and tries to communicate with the other device on the expected channel. If this fails, a full channel frequency agility mechanism can be applied.

In conclusion, according to the present invention it is possible to provide a novel procedure for a first coordinator that operates on a first channel frequency in a WPAN, the WPAN also comprising a second coordinator that operates on a second channel frequency, the procedure comprising the steps of transmitting a message on a plurality of channel frequencies, including the second channel frequency, requesting the second coordinator to switch from the second channel frequency to the first channel frequency, and establishing communications with the second coordinator using the first channel frequency. As described above, the advantages of the present invention include the fact that a priority-based mechanism is not needed because the coordinator initiating (eg establishing) the communication chooses the frequency used. In addition, each coordinator can make the coordinator they wish to communicate with change to their chosen frequency.