Patent Publication Number: US-2016234696-A1

Title: Detection of coexistence in devices using multiple wireless communication technologies

Description:
BACKGROUND 
     This disclosure concerns wireless coexistence in electronic devices that use wireless communication, and, in particular, the management of wireless coexistence to prevent conflicts such as interference. 
     Electronic devices equipped with wireless communication functionality are increasingly able to operate using two or more independent (typically different) wireless communication (radio frequency (RF)) technologies, which may have different communication protocols. Wireless coexistence may occur when such a device communicates using two independent wireless communication technologies that use the same or adjacent radio frequency bands simultaneously, and, a coexistence management mechanism (e.g., arbitration algorithm) should be used to prevent mutual interference between the different RF signals. 
     Typically, a first device capable of communicating using two different wireless communication technologies communicates with two different peer devices, each of which can only communicate using one of the wireless communication technologies as shown in  FIG. 1 . In this case, the wireless coexistence management mechanism in the first device operates to allow coexistence, typically time-domain based coexistence, without interference. However, a problem arises when communication is established between two electronic devices both communicating using two different wireless communication technologies as shown in  FIG. 2 . In particular, interference may occur due to conflicts arising in the coexistence management mechanisms (e.g., arbitration algorithms) operating in the two devices. 
     There is a need to more effectively manage wireless coexistence to prevent interference occurring, particularly when two devices are communicating with each other using two different wireless communication technologies employing different communication protocols. 
     SUMMARY 
     This Summary of the disclosure is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid to determining the scope of the claimed subject matter. 
     Methods are provided for detecting a wireless coexistence scenario in which two devices in communication with each other are both operating a coexistence management mechanism or algorithm. The detection of this wireless coexistence scenario may be used to provide a trigger to switch to an alternative coexistence management mechanism to prevent conflicts, which may disable a coexistence management mechanism operating in one of the devices, thereby preventing interference. 
     In one aspect, a method for wireless coexistence management is provided. The method is performed using a first device and comprises the steps of: monitoring signal samples of communications in accordance with first and second independent wireless communication technologies over a predetermined time period, the signal samples comprising samples of wireless communications between the first device and at least one peer device; processing the monitored signal samples to determine whether the monitored communications indicate the probable existence of a wireless coexistence scenario, in which the first device is communicating with a single peer device in accordance with both the first and second wireless communication technologies, and if the step of processing the monitored signal samples determines that the monitored communications indicate the probable existence of the wireless coexistence scenario, triggering a wireless coexistence management process. 
     In implementations of the method, the wireless coexistence management process comprises changing the wireless coexistence management mechanism operating in one of the first device, the peer device or both in order to prevent wireless coexistence problems. For example, the wireless coexistence management process may involve switching off the wireless coexistence mechanism in one of the first device and the peer device. 
     Changing the wireless coexistence management mechanism operating in one of the first device, the peer device or both may be accomplished by either making a decision locally on the first device, or using the first wireless communication technology or the second wireless communication technology to signal to the peer device and coordinate coexistence management activity. 
     In implementations, the step of processing the monitored signal samples to determine whether the monitored communications indicate the probable existence of the wireless coexistence scenario comprises: sampling signals of communications in accordance with the first and second wireless communication technologies for a predetermined time period, each signal sample comprising signals communicated during a predefined sampling period; and, for each signal sample: determining whether a valid received (Rx) signal in accordance with the first wireless communication technology is communicated during a predefined time slot (or trigger period) of the sampling period; determining whether a valid transmitted or received (Tx/Rx) signal in accordance with the second wireless communication technology is communicated during the predefined time slot of the sampling period, and if it is determined that both a valid received (Rx) signal in accordance with the first wireless communication technology and a valid transmitted or received (Tx/Rx) signal in accordance with the second wireless communication technology are communicated during the predefined sampling period, determining that the monitored communications do not indicate the probable existence of the wireless coexistence scenario. 
     The method may further comprise the steps of: prior to the step of monitoring signal samples, determining the predetermined time period for sampling a selected number of signal samples to be processed in order to indicate the probable existence of the wireless coexistence scenario to a predetermined degree of certainty, wherein: if, for a predetermined proportion of the selected number of signal samples, it is not determined that both a valid received (Rx) signal in accordance with the first wireless communication technology and a valid transmitted or received (Tx/Rx) signal in accordance with the second wireless communication technology are communicated during the predefined sampling period, determining that the monitored communications indicate the probable existence of the wireless coexistence scenario to the predetermined degree of certainty. The predefined time slot of the sampling period may comprise a known receive (Rx) time slot for signals communicated in accordance with the first wireless communication technology. 
     In implementations, the selected number of signal samples is determined to provide a statistically meaningful sample size for determining the probability of the wireless coexistence scenario to an acceptable degree of certainty for the relevant application. This will vary with application requirements. 
     In certain, active implementations, the method may further comprise the step of: prior to the step of monitoring the signal samples, transmitting a signal in accordance with the first communication technology in order to provoke a response from at least one peer device. Transmission of the signal in accordance with the first communication technology may further be timed so that a response from at least one peer device is received during a known time slot for signals received in accordance with the second communication technology. The signal transmitted in accordance with the first communication technology may comprise a NULL packet or other similar packet. 
     In such active implementations, the method may further comprise the steps of: prior to the step of transmitting a signal in accordance with the first communication technology, identifying a time slot for the transmission of the signal; determining whether there is sufficient time to send the signal within the identified time slot, and if it is determined that there is sufficient time to send the signal, determining a correct time for transmitting the signal; wherein the step of transmitting a signal in accordance with the first communication technology is performed at the determined correct time so that a response from at least one peer device is received during the predefined time slot of the sampling period. 
     In the case of a first wireless communication technology in which multiple devices must contend for the transmission medium, the method may further comprise: contending for a transmission medium for communication in accordance with the first communication technology, prior to the step of transmitting a signal in accordance with the first communication technology. In some implementations, the method may further comprise the step of contending for a transmission medium comprises reserving the transmission medium for a desired time period. 
     In yet another aspect, a method is provided for detecting a wireless coexistence scenario in which two peer devices in communication with each other are both operating a coexistence management mechanism. The method comprises actively transmitting a communication, in accordance with one of two independent communication technologies, for provoking a desired response. The method further comprises passively monitoring wireless communications in accordance with the two communication technologies received in response. The methods further comprise determining whether the monitored communications indicate that the wireless coexistence scenario exists. 
     In one implementation, a method is provided for determining that the wireless coexistence scenario exists based on processing of signals received in response to the active transmission for provoking a desired response. 
     In another implementation, the method comprises determining a time or time period for the transmission of the communication to provoke a desired response in a predetermined time period or at a predetermined time. In this way, the timing of the transmission can be controlled to provoke the desired response so that the existence of the wireless coexistence scenario may be determined quickly (within a desired time period) and/or to a high degree of certainty. 
     In another aspect, a method for determining the probable existence of a wireless coexistence scenario, in which two devices are communicating with each other using first and second independent wireless communication technologies, is provided. The method is performed using a first device and comprises the steps of: sampling signals in accordance with the first and second wireless communication technologies for a predetermined time period, each signal sample comprising signals communicated during a predefined sampling period; and, for each signal sample: determining whether a valid received (Rx) signal in accordance with the first wireless communication technology is communicated during a predefined time slot (or trigger period) of the sampling period; determining whether a valid transmitted or received (Tx/Rx) signal in accordance with the second wireless communication technology is communicated during the predefined time slot of the sampling period, and if it is determined that both a valid received (Rx) signal in accordance with the first wireless communication technology and a valid transmitted or received (Tx/Rx) signal in accordance with the second wireless communication technology are communicated during the predefined sampling period, determining that the monitored communications do not indicate the probable existence of the wireless coexistence scenario. 
     It will be appreciated that the steps of the methods according to the disclosure may be implemented in real-time by directly monitoring/sampling appropriate signals in accordance with the first wireless communication technology and the second wireless communication technology. The methods may also be implemented by recording (i.e., storing in memory) signal samples for the first wireless communication technology and the second wireless communication technology. In the latter case, the steps of the methods may be applied to the stored data sets at a later time, for example at the end of a predetermined sampling period. 
     Other aspects of the disclosure will be apparent, from the following detailed description and the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments that represent implementations of this disclosure will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a first example of a wireless coexistence scenario; 
         FIG. 2  shows a second example of a wireless coexistence scenario; 
         FIGS. 3A and 3B  are flow diagrams showing a method for identifying the wireless coexistence scenario of  FIG. 2  in accordance with a first example implementation of the present disclosure; 
         FIGS. 4A and 4B  are flow diagrams showing a method for identifying the wireless coexistence scenario of  FIG. 2  in accordance with a second example implementation of the present disclosure; 
         FIG. 5A  is a schematic diagram of typical traffic signals communicated in accordance with the scenario of  FIG. 1  and  FIG. 5B  is a schematic diagram of typical traffic signals communicated in accordance with the scenario of  FIG. 2 ; 
         FIG. 6  is a flow diagram showing a method for identifying the wireless coexistence scenario  2  in accordance with a third example implementation of the present disclosure; 
         FIG. 7  is a timing diagram of example Wi-Fi and Bluetooth signals showing the time slots of a typical time-domain based coexistence scheme for 2.4 GHz Wi-Fi and Bluetooth; 
         FIG. 8  is a schematic diagram showing the timings of an average NULL/ACK exchange; 
         FIG. 9  is a timing diagram showing the timings of the time slots of the example Wi-Fi and Bluetooth signals of  FIG. 7 , and 
         FIG. 10  is a timing diagram showing the timings of example Wi-Fi and Bluetooth signals of  FIG. 7  in which the RTS/CTS medium reservation mechanism is used. 
     
    
    
     Common reference numerals are used throughout the drawings to denote the same or similar features. 
     DETAILED DESCRIPTION 
     Embodiments of this disclosure are described below by way of example only. These examples represent the best implementations of the disclosure presently contemplated by the applicant. Nevertheless, numerous other implementations, for putting the disclosure into practice, may be used and are within the scope of the invention. 
       FIG. 1  shows a first example of a wireless coexistence scenario. In this example, a first device  10  (Product) is capable of communicating using two different wireless communication technologies, i.e., Radio  1  and Radio  2 . Second and third devices  20 ,  30  (Peer  1  and Peer  2 ) are each capable of communicating using only one wireless communication technology, namely Radio  1  and Radio  2 , respectively. In this case, a conventional wireless coexistence management mechanism (e.g., arbitration algorithm) in the first device  10  operates to allow coexistence without interference. For example, the wireless coexistence management mechanism may be an arbitration scheme as defined in IEEE standard 802.15.2-2003 “Coexistence of Wireless Personal Area Networks with Other Wireless Devices Operating in Unlicensed Frequency Bands, so as to prevent interference between the Radio  1  and Radio  2  signals”. 
       FIG. 2  shows a second example of a wireless coexistence scenario. In this example, first (Product) device  10 ′ device and second (Peer) device  20 ′ are both capable of communicating using two different wireless communication technologies, i.e., Radio  1  and Radio  2 , respectively. In this wireless coexistence scenario, during simultaneous communication between the first and second devices  10 ′,  20 ′ using both Radio  1  and Radio  2 , each of the first and second devices  10 ′,  20 ′ may operate a conventional wireless coexistence management mechanism. However, the operation of two coexistence management mechanisms at the same time may conflict, or otherwise lead to mutual interference between the coexistence management mechanisms, and thus may not prevent interference between the Radio  1  and Radio  2  signals, which may lead to communication problems such as data loss or corruption. 
     The following description sets out details of certain example implementations or embodiments of this disclosure, in which the wireless coexistence scenario of  FIG. 2  is identified. In addition, action may be taken to avoid conflicts and/or interference arising with the wireless coexistence scenario of  FIG. 2  due to the use of two coexistence management mechanisms (e.g., arbitration algorithms). 
     In particular, the following example implementations are methods that may be implemented in a first device that is communicating with at least a second, peer device. For example, the first device may comprise a vehicle head unit (e.g., media centre) comprising a module for both Wi-Fi and Bluetooth wireless communication technologies on a single or multiple chips (ICs). The Front-End configuration of the first device should allow traffic in the Rx direction to be received by both wireless communication technologies simultaneously. The second device may comprise a portable computing device such as a smart phone, tablet, laptop etc. It will be appreciated that many other applications for the method are possible and contemplated. 
     The methods may be performed when a coexistence management mechanism (e.g., arbitration algorithm) is active in the first device, meaning the first device is simultaneously communicating using two independent, typically different, wireless communication technologies, e.g., Wi-Fi and Bluetooth. The methods operate to perform the functional steps of: (i) determining whether a second, peer device, with which the first device is communicating, is also simultaneously communicating using the two independent communication technologies, and so also operating a coexistence management mechanism, and (ii) determining whether to change the coexistence management based on the outcome of step (i). 
     Example Implementation 1 
     Passive Detection 
       FIGS. 3A and 3B  illustrate a method for identifying the wireless coexistence scenario of  FIG. 2  in accordance with a first example implementation of the present disclosure. As will be appreciated from the following, the methods implementing the present disclosure are probabilistic, in the sense that they identify the probable existence of the wireless coexistence scenario of  FIG. 2  according to a predetermined degree of certainty/level of confidence. In this example implementation, the technique is said to be “passive”, in the sense that the method does not actively send signals to provoke a desired response, which may be indicative of the existence (or alternatively the non-existence) of the wireless coexistence scenario. 
     The method of this implementation is particularly useful in applications where it is not possible, or is difficult, to distinguish between Tx and Rx packets of one of the communication technologies (e.g., Bluetooth), as explained in more detail below. In this example, the first communication technology is Wi-Fi and the second communication technology is Bluetooth. 
       FIG. 3A  is a flow diagram, the blocks of which show the main steps of the method of this first example implementation that encompass both of the abovementioned functional steps (i) and (ii). 
     The method starts at block  310  and at block  320  sets an initial count corresponding to the number of detected signal samples required so as to determine wireless coexistence at the second, peer device to a predetermined degree of accuracy 
     In particular the initial count should represent a statistically meaningful sample size for determining the probability of the wireless coexistence scenario to an acceptable degree of certainty, whilst doing so at an acceptable speed, for the relevant application. It will be appreciated that the use of a large sample size has the advantage of greater statistical value (i.e., greater probabalistic certainty) but the disadvantage of slower determination speed. Thus, the conflicting requirement for accuracy and speed will need to balanced, depending on the application. In one example, the sample size may be 5 (five), where each signal sample is acquired over a period of 1 (one) second. Thus, the initial count corresponding to the sample size establishes a predetermined monitoring time period for signal monitoring, in this case  5  (five) seconds. 
     The method samples and evaluates received Wi-Fi (Rx) signals and Bluetooth signal activity (Rx/Tx signals). In particular, during the sampling period of a first signal sample, the method evaluates the sample at block  330 , using an “Evaluate Function”, to determine whether the signal sample indicates wireless coexistence at the second, peer device. The Evaluate Function block  330  of this example implementation is described in further detail below with reference to FIG.  3 B. It will be appreciated that whilst in this example implementation sampling and evaluation is performed substantially in real time, in other example implementations the samples may be stored and evaluated at a later time. 
     At block  340 , the method decrements the count by one, and at block  350  determines if the count is greater than zero. If the count is greater than zero, the method returns to block  330  for evaluating the next sample. If the count is not greater than zero (i.e., equal to zero), then the required number of signal samples (corresponding to the initial count/sample size) has been evaluated and the method proceeds to block  360 . 
     At block  360  the method combines the evaluation results for all of the evaluated signal samples and determines whether wireless coexistence in the second, peer device is “assumed” (statistically probable) or “disproved” (statistically disproved). In particular, wireless coexistence is disproved if some or all of the evaluated signals samples indicate that there is no wireless coexistence in the second, peer device. On the other hand, wireless coexistence is assumed (i.e., coexistence is statistically probable) if a predetermined number or proportion of the evaluated signal samples, typically 100% of the signal samples, indicate that wireless coexistence in the second, peer device is not disproved. It will be appreciated that the number or proportion of signal sample results for a determination that the wireless coexistence scenario exists (or not) will be dependent on the level of confidence/certainty required for the particular application. 
     If, on the one hand, the result of the determination in block  360  is “coexistence disproved”, the method proceeds to block  370  in which the method performs predetermined processing for the case where there is no wireless coexistence in the second, peer device and the method ends at block  380 . For example, block  370  may continue to operate the wireless coexistence management mechanism (e.g., arbitration algorithm) in the first device. If, on the other hand, the result of the determination in block  360  is “coexistence assumed”, the method proceeds to block  390  in which the method performs predetermined processing for the case where there is wireless coexistence in the second, peer device. For example, block  390  may switch off the wireless coexistence management mechanism (e.g., arbitration algorithm) in the first device (or, alternatively, in the second device), or the coexistence management may otherwise be changed, so as to prevent conflict and/or interference between the wireless coexistence mechanisms operating on the first and second devices. Thereafter, the method ends at block  380 . 
       FIG. 3B  is a flow diagram, the blocks of which show the steps of the “Evaluate Function” of this example implementation that may be performed at block  330  of  FIG. 3A . As previously mentioned, the Evaluate Function evaluates the Wi-Fi Rx and Bluetooth (Rx/Tx) signals during each sampling period over the predetermined monitoring time period. As will be appreciated from the following description, the Evaluate Function is able to disprove the wireless coexistence scenario of  FIG. 2 , by detecting two simultaneous Rx signals using the two independent communication technologies. It will be appreciated that, in this disclosure, the term “simultaneous signals” is not intended to be limited to signals at exactly the same time, but rather refers to signals occurring in the same timeslot or immediately adjacent timeslots. 
     The method starts at block  410  and at block  420  starts a timer, which is set to run for a predetermined time period. The method proceeds to block  430 , which determines whether the timer has reached timeout (i.e., the timer has run for the predetermined time period, and thus expired). If the timer has timed out, the method sets the value for wireless coexistence as “true” indicating that the wireless coexistence scenario of  FIG. 2  is not disproved and ends at block  480  with the final evaluation result as “true”. Alternatively, if the timer has not timed out, the method proceeds to block  450 . 
     At block  450 , the method determines whether the signal sample includes a received signal in accordance with a first wireless communication technology, such as Wi-Fi. If block  450  determines that no Wi-Fi Rx signal is present, the method returns to block  430 . However, if block  450  determines that a Wi-Fi Rx signal is present in the signal sample, the method proceeds to block  460 . 
     At block  460 , the method determines whether the signal sample indicates signal activity using a second wireless communication technology, such as Bluetooth. For example, the method may determine whether the sample includes a transmitted and/or received signal in accordance with the second wireless communication technology during a predefined time slot, such as a combined transmit/receive (Tx/Rx) time slot of the second wireless communication technology. If block  460  determines that the second wireless communication technology is not active, the method returns to block  430 . However, if block  460  determines that the second wireless communication technology is active, then simultaneous Rx Wi-Fi and Rx/Tx Bluetooth signals are detected, thereby disproving the wireless coexistence scenario of  FIG. 2 . Accordingly, the method proceeds to block  470 , which sets the value for wireless coexistence to “false”. The method then proceeds to block  475 , which determines whether the timer has reached timeout (i.e., the timer has run for the predetermined time period, and thus expired). If the timer has timed out, the method proceeds to block  480 , otherwise the method repeats block  475 . The method then ends at block  480  with the final evaluation result as “false”. 
     Since block  460  merely determines whether the second wireless communication technology is active, the method of this example implementation can be used in applications, in which it is not possible to distinguish between Tx and Rx packets. For example, IEEE 802.15.2-2003 PTA schemes occasionally may be implemented as PIO signalling schemes with a single PIO indicating Bluetooth Rx and Tx activity, without supplying all the specified information in IEEE 802.15.2-2003. In this case the PTA scheme will not be able to easily differentiate between Tx and Rx Bluetooth signals. 
     It will be appreciated that various modifications may be made to the method of the example implementation of  FIGS. 3A and 3B . For example, the method may be implemented to identify the wireless coexistence scenario of  FIG. 2  with wireless communication technologies other than Wi-Fi and Bluetooth. 
     Example Implementation 2 
     Passive Detection (Alternative) 
       FIGS. 4A and 4B  illustrate an alternative method for identifying the wireless coexistence scenario of  FIG. 2  in accordance with a second, passive example implementation of the present disclosure. Similar to the example implementation of  FIGS. 3A and 3B , the second example implementation is passive (i.e., it merely monitors signal samples communicated between the first device and the second, peer device and does not actively send signals to provoke a desired response). However, in this example, the method is capable of distinguishing between transmitted (TX) and received (Rx) signals in accordance with the second wireless communications technology. As in the example implementation of  FIGS. 3A and 3B , in this example the first communication technology is Wi-Fi and the second communication technology is Bluetooth. 
       FIG. 4A  is a flow diagram, the blocks of which show the main steps of the method of this second example implementation that encompass both of the functional steps (i) and (ii) set out above. 
     The method starts at block  510  and at block  520  sets an initial count corresponding to the number of signal samples required to determine the probability of the wireless coexistence scenario of  FIG. 2  to a predetermined degree of certainty/level of confidence. The initial count may be determined using techniques similar to those described above in relation to block  320  of  FIG. 3A . In the method of this implementation, 100% of the signal samples must indicate that the wireless coexistence scenario may exist (i.e., is not disproved). In other implementations, the proportion of such examples may be less than 100%. Thus, the initial count may be a minimum number of samples necessary to lead to a determination that the wireless coexistence scenario of  FIG. 2  is probable to the predetermined degree of certainty. 
     The method samples and evaluates received Wi-Fi (Rx) signals and Bluetooth (Rx) signals. In particular, during the sampling period of a first signal sample, the method performs evaluation using a “Detect Function” at block  530  to determine whether the signal sample indicates that there is no wireless coexistence at the second, peer device (i.e., the wireless coexistence scenario of  FIG. 2  is disproved). The Detect Function block  530  of this example implementation is described in further detail below with reference to  FIG. 4B . It will be appreciated that whilst in this example implementation sampling and evaluation using the “Detect Function” is performed substantially in real time, in other example implementations the samples may be stored and evaluated at a later time. 
     At block  540 , the method determines whether the Detect Function indicates that there is no wireless coexistence in the second, peer device. If block  540  determines that there is no wireless coexistence, then the wireless coexistence scenario is disproved and the method proceeds to block  550 , in which the method performs predetermined processing for the case where there is no wireless coexistence in the second, peer device and the method ends at block  560 . However, if block  540  determines that there may be wireless coexistence in the second, peer device (i.e, the result of the Detect Function is “unknown”, as described below), the method proceeds to block  570 . 
     At block  570 , the method decrements the count by one, and at block  580  determines if the count is greater than zero. If the count is greater than zero, the method returns to block  530  for performing the Detect Function on the next signal sample. If the count is not greater than zero (i.e., equal to zero), then the required number of signal samples (corresponding to the initial count) have been evaluated and, in each case, the evaluation determined that there may be wireless coexistence in the second, peer device (i.e., the result of the Detect Function is “unknown”). Accordingly, the method determines that coexistence is statistically probable and proceeds to block  590 . At block  590 , the method performs predetermined processing for the case where there is wireless coexistence in the second, peer device, and, thereafter, the method ends at block  580 . 
     It is understood that the predetermined processing performed in blocks  550  and  590  may be similar to the processing performed in blocks  370  and  390 , respectively, of  FIG. 3A  of the first example implementation. 
       FIG. 4B  is a flow diagram, the blocks of which show the steps of the Detect Function of the example implementation that may be performed at block  530  of  FIG. 4A . The Detect Function evaluates the signal samples by detecting the presence of signals in a specific, individual time slot, also called the “trigger period” herein, of the signal sample. It will be appreciated that the time slots of the signal samples are predefined by, and will be dependent upon, the particular communication protocol implemented in the application in accordance with the corresponding wireless communication technology. 
     As shown in  FIG. 4B , the method starts at block  610  and at block  620  sets the result as “unknown”. The detect function then monitors the signal samples, received by the first device, over a predetermined time period. 
     In particular, it will be understood that the first and second wireless communication technologies may utilise predefined time slots to transmit and receive signals using the first and second wireless communication technologies in accordance with a time-domain based coexistence scheme. Examples of this are illustrated in  FIGS. 7, 9 and 10 , which depict the signal time slots of various coexisting Rx and Tx signals in accordance with Wi-Fi and Bluetooth communication technologies operating in the 2.4 GHz frequency band, as described in further detail below. 
       FIG. 5A  is a schematic diagram of typical traffic signals communicated in accordance with the scenario of  FIG. 1  in which the first device (Product) communicates with second and third (Peer) devices using Bluetooth and Wi-Fi communication technologies, respectively. The signals shown in  FIG. 5A  include two simultaneous transmit/receive (Tx/Rx) packets using Wi-Fi and Bluetooth, signifying that two different (second and third Peer) devices are transmitting simultaneously and there is no wireless coexistence management mechanism operating in a single device at the Peer end of the communications. 
       FIG. 5B  is a schematic diagram of typical traffic signals communicated by a first device (Product) and a second device (Peer) in a time-domain based coexistence scheme implementing Wi-Fi and Bluetooth communication technologies in accordance with the scenario of  FIG. 2 . In this case, Wi-Fi transmit/receive (Tx/Rx) packets are time separated from the Bluetooth transmit/receive (Tx/Rx) packets, and the time-domain based wireless coexistence scheme of  FIG. 2  may be present, requiring a wireless coexistence management mechanism operating in a single device at the Peer end of the communications. 
     Accordingly, the first device may monitor the Wi-Fi and Bluetooth traffic signals during a Bluetooth Rx slot (shown in the bottom half of  FIG. 5A / 5 B). If, during this Bluetooth Rx slot, valid Wi-Fi Rx traffic as well as valid Bluetooth traffic is present then it can be concluded that no wireless coexistence management mechanism (e.g., arbitration algorithm) is operating in the second and third (Peer) devices. 
     Returning to  FIG. 4B , at block  630  the method waits for the Bluetooth Rx time slot (Td2) to start. If block  630  determines that the time period Td2 has started, the method proceeds to block  640 . Block  640  determines if a valid Wi-Fi packet has been received. If block  640  determines that a valid Wi-Fi packet has not been received, the method proceeds to block  650 . Block  650  determines if the end of the Bluetooth Rx slot (Td2) has been reached. If block  650  determines that Td2 has not been reached then the method returns to block  640 , otherwise the method ends at block  670  with the result remaining as “unknown”. 
     If block  640  determines that a valid Wi-Fi packet has been received, the method proceeds to block  680 . Block  680  determines whether the Bluetooth Rx time slot (Td2) has expired. If the Bluetooth Rx time slot has not expired, the method repeats block  680  until the Bluetooth Rx time slot has expired. When block  680  determines that the Bluetooth Rx time slot (Td2) has expired, the method proceeds to block  690 . 
     At block  690 , the method determines whether the Bluetooth packet is valid after expiry of the Bluetooth Rx time slot (Td2). It will be understood that validity may be determined through the use of a checksum or the similar error detection technique. If block  690  determines that the Bluetooth packet is not valid, the method ends at block  670 , with the result remaining as “unknown”. However, if block  690  determines that the Bluetooth packet is valid, the method proceeds to block  660 , which sets the result to “no coexistence” and the method ends at block  670 . 
     It will be appreciated that various modifications may be made to the method of the example implementation of  FIGS. 4A and 4B . 
     In view of their “passive” approach, for identifying the wireless coexistence scenario of  FIG. 2 , the first and second example implementations rely on the second Peer device scheduling concurrent, time-domain separated, WiFi and Bluetooth traffic, which is probabilistic. Thus, these implementations may be successfully realised in applications and/or situations where there is a high level of active communications using both wireless communication technologies such that concurrent scheduling is likely. However, in some applications and/or situations, particular those in which speed of detection of the wireless coexistence scenario of  FIG. 2  is important, an “active” approach, that provokes the second Peer device into such concurrent scheduling and transmission, may be beneficial. An example of such an active implementation is described below. 
     Example Implementation 3 
     Active Detection 
       FIG. 6  is a flow diagram, the blocks of which show the main steps of the method of this third, active example implementation that encompass both of the functional steps (i) and (ii) described above. As in the methods of the first and second example implementations, the first wireless communication technology is Wi-Fi and the second communication technology is Bluetooth. In this active technique, the method actively initiates or provokes communications from a Peer device in order to detect signals indicative of the wireless coexistence scenario of  FIG. 2  and, thus, determine the existence of the scenario to a greater degree of certainty and/or more quickly by processing a smaller number of samples (typically just one, as described below). In particular, as described below, the method actively sends a relatively small, Wi-Fi Tx packet at a precisely controlled time during the Wi-Fi and Bluetooth timeslots to provoke a response, thereby increasing the probability of the simultaneous transmission of Wi-Fi and Bluetooth signals from a single or multiple peer devices. 
     The method starts a block  710  and at block  720  determines when the current time is in a time interval in the Bluetooth slot pattern that allows transmission of a Wi-Fi Tx packet without interfering with Bluetooth RF signals. As described in further detail below with reference to  FIG. 7 , a suitable time interval is the unused time, Tu, at the end of the Bluetooth Tx time slot. When block  720  determines a current time interval to allow the Wi-Fi Tx packet to be transmitted, at block  730  the method contends for the Wi-Fi medium. An example of this is described in further detail below with reference to  FIG. 7 , in which the Wi-Fi medium may be reserved for the transmission. At block  740 , the method determines whether there is sufficient time to send a Wi-Fi transmit (Tx) packet. If block  740  determines that there is insufficient time to send a Wi-Fi Tx packet, the method returns to block  720 , thereby waiting for the next Wi-Fi Tx timeslot. On the other hand, if block  740  determines that there is sufficient time to send a Wi-Fi Tx packet, the method proceeds to block  750 . 
     At block  750 , the method determines when it is a correct time to send the Wi-Fi Tx packet. An example of this is described in further detail below in relation to  FIG. 7 . When block  750  determines that it is the correct time to send the Wi-Fi Tx packet, the method proceeds to block  760  in which the Wi-Fi Tx packet is sent. 
     The method then proceeds to monitor the Wi-Fi and Bluetooth traffic signals. In particular the method evaluates a first received signal sample using a Detect Function at block  770  for determining whether the signal sample indicates that there is no wireless coexistence at the second, peer device. The Detect Function of block  770  of this example implementation may be as described above in relation to the second, passive implementation with reference to  FIG. 4B . It will be appreciated that whilst the Detect Function may implement the same or similar steps as used in the second, passive example implementation of  FIG. 4B , in this third, active example implementation, the likelihood of the Wi-Fi Rx event happening, in a manner that enables the scenario of  FIG. 2  to be disproved, has been increased. Thus, the outcome of the active example implementation has a greater degree of certainty compared to the passive example implementations. 
     Once the Detect Function block  770  provides a result, at block  780  the method determines whether the Detect Function result is that there is no wireless coexistence in the second, peer device. If block  780  determines that there is no wireless coexistence, then the method proceeds to block  785 , in which the method performs predetermined processing for the case where there is no wireless coexistence in the second, peer device and the method ends at block  790 . 
     However, if block  780  determines that the Detect Function result is that there may be wireless coexistence in the second, peer device (i.e., the result is “unknown”) the method proceeds to block  795 , in which the method performs predetermined processing for the case where there is wireless coexistence in the second, peer device, and, thereafter, the method ends at block  790 . 
     It is understood that the predetermined processing performed in blocks  785  and  795  may be similar to the processing performed in blocks  370  and  390 , respectively, of  FIG. 3A  of the first example implementation. 
     In addition to the greater degree of certainty of the outcome resulting from the use of this active example implementation, compared to the passive example implementations described above, it has the additional advantage of determining a result more quickly. In particular, the method of  FIG. 6  merely evaluates a single sample. Provided that the Wi-Fi signal is successfully transmitted at the correct time, this approach should provide a result with an acceptable degree of certainty. It will be appreciated that, in other active example implementations, the method of  FIG. 6  may be repeated to evaluate one or more further signal samples, in the event that the result of the Detect Function at block  770  on the first signal sample is “unknown”, so as to increase the degree of certainty that the wireless coexistence scenario of  FIG. 2  exists. 
     It will be appreciated that various modifications may be made to the method of the example implementation of  FIG. 6 . 
       FIG. 7  is a timing diagram showing the timeslots of example typical Bluetooth and Wi-Fi traffic signals communicated by a first device (Product) comprising an IEEE 802.11 STA and a second device (Peer) comprising an IEEE 802.11 Access Point, in accordance with the method of  FIG. 6 . It will be appreciated that the sequence, values etc., of the Bluetooth and Wi-Fi Tx/Rx timeslots will vary with other example applications, and may even be dependent on the choice of vendor hardware (chips) employed. 
     The example of  FIG. 7  shows Bluetooth (the top trace) as master of a link but this method should apply equally well when running as slave of a link. 
     Bluetooth is based around 625 μs (Tx and Rx) timeslots so the first, Bluetooth Tx slot shown in  FIG. 7  comprises: 
       625 μs=Tl1 +Td 1+Tt+Tu
 
     Where:
         Tl1 is the lead time to allow the Bluetooth radio to ramp up and become ready to transmit (comprising the radio ramp and unmodulated carrier)   Td1 is the time spent transmitting the data packet and training sequence   Tt is the tail time to allow ramping down of the Bluetooth radio   Tu is the unused time at the end of the slot.       

     Thus, the unused time Tu at the end of the Bluetooth Tx timeslot may be used to transmit a Wi-Fi Tx packet to provoke a response from the peer device. A relatively small Tx data packet, such as a poll or NULL packet, can be used in order to elicit data from a peer device such that it can be assumed that Td1 is quite small, approximately 128ρs. Average values for Tl1 and Tt are approximately 40 μs for Tl1 and in the region of 16 μs for Tt. 
     Therefore: 
       Tu=625 μs−Tl1 −Td 1−Tt
 
       Tu=441 μs
 
     The Bluetooth Rx slot of  FIG. 7  can be divided into two parts for the purposes of this example, namely:
         Tl2 is the lead time taken to switch the Bluetooth radio to Rx, and   Td2 is the time taken to receive the data packet       

     The timing diagram of  FIG. 7  is based on the use of Bluetooth products of the applicant, Cambridge Silicon Radio Limited, on the basis of which it can be further assumed that Tl2 is in the region of 16 μs. Therefore the time available for Wi-Fi to Tx before starting the Bluetooth Rx slot activity will be 429 μs. 
     Between Tu-Tl2 is will be possible to transmit and receive Wi-Fi traffic. Thus, the time Tl2 may also be available to transmit, or continue to transmit, a Wi-Fi Tx packet (e.g., NULL packet) to provoke a response from the peer device, i.e., Wi-Fi Rx packet (e.g., ACK packet). During Tl2 and Td2 it will be possible to receive Wi-Fi traffic. It is assumed that some coexistence solutions may take opportunity of Wi-Fi activity during Tu and Tl2. 
     Thus, in this example, the time interval Td2 is considered to be the “trigger period”, this being the time slot in which it is expected that a response from the peer device will be received in the case of the scenario of  FIG. 1  (i.e., the scenario of  FIG. 2  is disproved). To provoke Wi-Fi Rx traffic from a peer device during Td2, the correct time to send out a Tx packet, such as a NULL packet, should be just before Tl2 starts (i.e., during Tu).  FIG. 7  shows an example of this Wi-Fi activity (the bottom trace). 
     The timings of an average NULL/ACK exchange are given in  FIG. 8 . This example is based around IEEE 802.11g and using the lowest IEEE 802.11g modulation rate, so that the packet sizes and timings involved work together with the timings set out above. By selecting a lower modulation rate, the data exchanges are longer and overlap with Td2 rather than the ACK being received in Tl2. 
     A full example of all the timings involved in the example of  FIG. 7  is shown in  FIG. 9 . It will be appreciated that in other implementations, the timings may differ significantly from those illustrated according to the application (wireless communication technologies) and the type of Tx packet chosen to provoke a response. However, in all cases, there will be a period corresponding to the described “trigger period” Td2, in which signals may be received in accordance with the first and second communication technologies (i.e., the scenario of  FIG. 2  is disproved), and a time period, corresponding to the described unused time period Tu, before the “trigger period”, in which the Tx packet can be transmitted. The determination of whether there is sufficient time in block  740  of  FIG. 6  and the determination of the correct time in block  750  of  FIG. 6 , both of which are carried out during the time period Tu, will depend on multiple factors including the length of the relevant time periods (Tu and Td2), the time between transmitting the Tx packet and receiving the Rx packet in response etc. 
     It will be appreciated that the method of each of the above-described example implementations  1  to  3  may be typically carried out in software but optionally in firmware or hardware, in any suitable electronic communications device. Thus, the disclosure encompasses a computer readable medium comprising instructions that, when executed by a processor, perform the above described method. 
     Advantageously, the methods performed by the first device according to the present disclosure permit determination of the probable existence of the wireless coexistence scenario of  FIG. 2  independent of the type and vendor of the other, peer devices. Typically, the determination of the probable existence of the wireless coexistence scenario triggers a wireless coexistence management process solely within the first device, and thus also independent of the type and vendor of the other, peer devices. 
     It will be understood that the above description of example implementations of the disclosure is given by way of example only and that various modifications may be made by those skilled in the art. For example, whilst the implementations have been described in relation to specific wireless communication technologies, the method of the disclosure may be applied using other wireless communication technologies that give rise to wireless coexistence scenarios. Although various implementations have been described above with a certain degree of particularity, or with reference to one or more individual example implementations and techniques, those skilled in the art could make numerous alterations to the implementation disclosed without departing from the spirit or scope of the invention. 
     The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present disclosure as a whole in light of the common general knowledge of the skilled person, irrespective of whether such features or combination of features solve any problems disclosed herein. The applicant indicates that aspects of the invention may consist of any such individual feature or combination of features.