Communication Apparatus and ID Packet Recognition Method Thereof

Abstract

A communication apparatus is provided. The communication apparatus includes an RF module and a scan module coupled to the RF module. The RF module receives an RF signal and generates an intermediary signal corresponding to the RF signal. The scan module recognizes a time-domain pattern corresponding to the intermediary signal, and determines whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/324,340, filed on Apr. 15, 2010, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a communication apparatus, and more particularly to a communication apparatus for recognizing an ID packet comprised in an RF signal.

2. Description of the Related Art

Bluetooth wireless technology is a short-range communications technology, which is able to replace cables which connect portable and/or fixed devices for communications while maintaining high levels of security. The key features of Bluetooth technology are robustness, low power, and low cost. The Bluetooth specification defines a uniform structure for a wide range of devices to connect and communicate with each other.

All Bluetooth devices default to a standby mode. In a standby mode, unconnected devices periodically listen for messages. This procedure is called scanning which is divided into two types: page scan and inquiry scan. A page scan is defined as a connection sub-state in which a device listens for its own device access code (DAC) (via a “page”) for a scan window duration (11.25 ms) every 1.28 seconds in order to set up an actual connection between devices. An inquiry scan is very similar to a page scan except that in this sub-state the receiving device scans for the inquiry access code (IAC) (via an “inquiry”). The inquiry scan is used to discover which devices are in a range and addresses and clocks of devices in the range. Therefore, a normal scan procedure is typically performed during the scan window (11.25 ms) for a Bluetooth device.

A page sub-state is used by a master Bluetooth device to activate and connect to a slave Bluetooth device which periodically wakes up in the page scan sub-state. The master Bluetooth device tries to capture the slave Bluetooth device by repeatedly transmitting the slave's device access code (DAC) in different hop channels. In the page sub-state, the master Bluetooth device transmits the device access code (ID packet) corresponding to the targeted slave Bluetooth device for connection, rapidly on a large number of different hop frequencies. Since the ID packet is a very short packet, the hop rate can be increased from 1600 hops/s to 3200 hops/s. Since the Bluetooth clocks of the master and the slave Bluetooth devices may not be synchronized, in this case, the master Bluetooth device would not precisely know when the slave Bluetooth device has waken up and which hop frequency the slave Bluetooth device is on. Therefore, the master Bluetooth device transmits a train of identical DACs at different hop frequencies, and listens in between the transmitted intervals until the master Bluetooth device receives a response from the slave Bluetooth device. FIG. 1 shows a timing diagram illustrating page and inquiry scan transmissions, wherein pairs of page or inquiry scan messages 100 are repeated within the scan window (11.25 ms) in accordance with the Bluetooth specification.

However, when in standby mode, a Bluetooth device will consume power due to the inquiry scan and the page scan. This can be undesirable in that considerable battery power is consumed even while the Bluetooth device is unconnected.

Therefore, a communication apparatus and a Bluetooth ID packet recognition method thereof are desired to reduce power consumption of the communication apparatus when in a standby mode.

BRIEF SUMMARY OF THE INVENTION

A communication apparatus for recognizing an ID packet comprised in an RF signal and a method thereof are provided. An embodiment of a communication apparatus is provided. The communication apparatus comprises an RF module and a scan module coupled to the RF module. The RF module receives an RF signal and generates an intermediary signal corresponding to the RF signal. The scan module recognizes a time-domain pattern corresponding to the intermediary signal, and determines whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

Furthermore, another embodiment of a communication apparatus is provided. The communication apparatus comprises an RF module and a scan module. The RF module receives an RF signal. The scan module is coupled to the RF module and has at least two scan modes comprising a fast scan mode and a normal scan mode, wherein when operating in the fast scan mode, the scan module recognizes a time-domain pattern corresponding to the RF signal and determines whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

Moreover, an embodiment of a method for recognizing an ID packet comprised in an RF signal is provided. An RF signal is received and an intermediary signal corresponding to the RF signal is generated. A fast scan procedure is performed by recognizing a time-domain pattern corresponding to the intermediary signal, and determining whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 shows a timing diagram illustrating page and inquiry scan transmissions;

FIG. 2A shows a communication apparatus for recognizing ID packets according to an embodiment of the invention;

FIG. 2B shows a communication apparatus for recognizing ID packets according to another embodiment of the invention;

FIG. 3 shows an example illustrating a timing diagram of the signals of the communication apparatus in FIG. 2A or FIG. 2B according to an embodiment of the invention;

FIG. 4 shows an example illustrating a diagram of the power detection signal S_power of the communication apparatus in FIG. 2A or FIG. 2B according to an embodiment of the invention;

FIG. 5 shows another example illustrating a diagram of the power detection signal S_power of the communication apparatus in FIG. 2A or FIG. 2B according to an embodiment of the invention;

FIG. 6 shows another example illustrating a diagram of the power detection signal S_power of the communication apparatus in FIG. 2A or FIG. 2B according to an embodiment of the invention;

FIG. 7 shows another example illustrating a diagram of the power detection signal S_power of the communication apparatus in FIG. 2A or FIG. 2B according to an embodiment of the invention; and

FIG. 8 shows an ID packet recognition method for a communication apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

FIG. 2A shows a communication apparatus 200 for recognizing an ID packet according to an embodiment of the invention. The communication apparatus 200 comprises an RF module 210, an analog to digital converter (ADC) 220, and a scan module 230. In FIG. 2A, the RF module 210 receives an RF signal via an antenna 260. Next, the ADC 220 receives a signal from the RF module 210 and converts the received signal into a digital signal S_D. Next, the scan module 230 may perform a fast scan procedure on the digital signal S_D to recognize a time-domain pattern corresponding to the digital signal S_D and to determine whether the RF signal received by the RF module 210 comprises an ID packet according to the recognized time-domain pattern. More specifically, the scan module 230 compares the recognized time-domain pattern with a predefined ID pattern, and determines that the RF signal comprises the ID packet when the comparison result indicates that the recognized time-domain pattern matches the predefined ID pattern. The time-domain pattern may comprise a power distribution pattern. As shown in FIG. 2A, the scan module 230 comprises a power detection unit 240 and a packet recognition unit 250. The power detection unit 240 periodically detects the power of the digital signal S_D to obtain a power detection signal S_power. Next, the packet recognition unit 250 may determine whether the RF signal comprises the ID packet according to a power distribution pattern of the power detection signal S_power in time-domain and provides a power decision result S_result for subsequent processes. For example, after recognizing the Bluetooth ID packet from the RF signal, the communication apparatus 200 may detect that a peer Bluetooth device which sent the Bluetooth ID packet is nearby, and then the communication apparatus 200 may determine whether to set up a connection link with the nearby Bluetooth device according to the Bluetooth ID packet.

In one embodiment, the communication apparatus 200 may further comprise a down converter coupled between the RF module 210 and the scan module 230 (as shown in FIG. 2B) for down converting the signal from the RF module 210 to generate an intermediary signal, such as an intermediate frequency (IF) signal or a Baseband signal, and then the scan module 230 may perform a fast scan procedure according to the intermediate signal, to recognize whether a Bluetooth ID packet is received. Furthermore, the ADC 220 may be implemented between the power detection unit 240 and the packet recognition unit 250 rather than prior to the power detection unit 240, as shown in FIG. 2B, so as to reduce conversion distortion caused by the ADC 220 and obtain the power detection signal S_power accurately. In other words, the power detection can be implemented in either analog or digital domain, and in either RF bands, IF bands or basebands.

FIG. 3 shows an example illustrating a timing diagram of the signals of the communication apparatus 200 in FIG. 2A or FIG. 2B according to an embodiment of the invention. In FIG. 3, signal S1 represents a Bluetooth ID packet format (in this embodiment, eight slots ST1-ST8 are shown as example), and signal S2 represents a power waveform of the signal S1 received by the RF module 210 of FIG. 2A or FIG. 2B. Taking FIG. 2A as an example, the power detection unit 240 may obtain the power detection signal S_power by sampling the digital signal S_D and comparing the sample values with a threshold value. Therefore, the power detection signal S_power is at a high logic level “1” when the signal S2 has exceeded the threshold value, and the power detection signal S_power is at a low logic level “0” when the signal S2 has not exceeded the threshold value. If the ID packet exists, at least two power peaks (for example, the peaks in slot ST1 and ST2, or the peaks in slot ST2 and slot ST5) of the digital signal S_D will be detected by the power detection unit 240 over 1005.5 μs. Thus, the power detection unit 240 may provide the power detection signal S_power comprising N-bit power distribution patterns covering at least 1005.5 μs to express the power distribution of the digital signal S_D. Although N-bit hard decision is described here as an example, it should be noted that soft power information can also be employed to detect the two power peaks.

FIG. 4 shows an example illustrating a diagram of the power detection signal S_power of the communication apparatus 200 in FIG. 2A or FIG. 2B according to an embodiment of the invention. In the embodiment, each time period T1 includes N sub-periods (e.g. 18 sub-periods, each substantially equal to 72 μs) and each of the N bits indicates the power level during a corresponding sub-period within T1. It is to be noted that the time-length of the time period T1 must be large enough to cover 1005.5 μs, so as to contain at least two power peaks of the digital signal S_D, as described above. In FIG. 4, the power distribution pattern is composed of 18 bits. Two different power distribution patterns P1 and P2 are shown in FIG. 4. After receiving the power detection signal S_power, the packet recognition unit 250 determines whether the power distribution pattern P1 or P2 matches a predefined Bluetooth ID pattern. If the power distribution pattern matches a predefined Bluetooth ID pattern, the packet recognition unit 250 determines that a Bluetooth ID packet is detected. As can be seen from FIG. 3, ID packets can be expressed as two bits with high logic level “1” separated by a time interval close to 312.5 μs or 937.5 μs. In the power distribution pattern P1, label 41 constituted by two bits with a high logic level “1” separated by 2 bits with a low logic level “0” is close to 312.5 μs. In the power distribution pattern P2, label 42 constituted by two bits with a high logic level “1” separated by 10 bits with a low logic level “0” is close to 937.5 μs. Therefore, the power distribution patterns P1 and P2 match one type of Bluetooth ID pattern, respectively.

FIG. 5 shows another example illustrating a diagram of the power detection signal S_power of the communication apparatus 200 in FIG. 2A or 2B according to an embodiment of the invention. Similarly, in FIG. 5, the power distribution pattern is obtained by detecting the power of the digital signal S_D every 72 μs for 18 times. Furthermore, two different power distribution patterns P3 and P4 are shown in FIG. 5. After receiving the power detection signal S_power, the packet recognition unit 250 of FIG. 2A or 2B may provide the power decision result S_result to indicate that whether the power distribution pattern P3 or P4 matches a Bluetooth ID pattern. For example, in the power distribution pattern P3, no two bits with a high logic level “1” are separated by 312.5 μs or 937.5 μs, and the number of continuous bits with a high logic level “1” is larger than or equal to a specific value (e.g. ≧4), as shown in label 51; thus the packet recognition unit 250 may determine that the power distribution pattern P3 does not match any Bluetooth ID pattern and is a noise/interference pattern. In addition, in the power distribution pattern P4, although two bits with a high logic level “1” separated by 2 bits with a low logic level “0” are detected (label 52 and label 53), the packet recognition unit 250 still determines that the power distribution pattern P4 does not match a Bluetooth ID packet because there are four continuous separation groups each composed of a bit with a high logic level “1” and one or more bits with a low logic level “0” subsequent to the bit with a high logic level “1”, as shown in labels 54, 55, 56 and 57 of FIG. 5. Due to the number of continuous separation groups of the power distribution pattern P4 being larger than or equal to a specific value (e.g. ≧4), the packet recognition unit 250 may determine that the power distribution pattern P4 matches a noise/interference pattern rather than a Bluetooth ID pattern and provide the power decision result S_result to notify subsequent circuits, wherein the specific value is determined according to implementation choice.

FIG. 6 shows another example illustrating a diagram of the power detection signal S_power of the communication apparatus 200 in FIG. 2A or 2B according to an embodiment of the invention. Similarly, in FIG. 6, each power distribution patterns P5-P8 is obtained by detecting the power of the digital signal S_D every 72 μs for 18 times. In this embodiment, each of the power distribution patterns P5, P6, P7 and P8 has no bit with a high logic level “1”, which means that the power of the digital signal S_D has not exceeded the threshold value during four continuous fast scan procedures. In this situation where the time-domain patterns indicate that no power or low power level has been detected for a given time period, the scan module 230 may switch from the fast scan mode to the normal scan mode, and the normal scan procedure may be performed during a scan window (11.25 ms) to further confirm whether the RF signal received by the antenna 260 comprises any Bluetooth packets or noise.

FIG. 7 shows another example illustrating a diagram of the power detection signal S_power of the communication apparatus 200 in FIG. 2A or 2B according to an embodiment of the invention. Similarly, the power distribution pattern P9 is obtained by detecting the power of the digital signal S_D every 72 μs for 18 times. In this embodiment, the number of continuous bits with a high logic level “1” of the power distribution pattern P9 is larger than or equal to a specific value (e.g. 16). Thus, the packet recognition unit 250 may determine that the power distribution pattern P9 does not match a Bluetooth ID pattern and provide the power decision result S_result to notify subsequent circuits. In this situation where the time-domain pattern indicates that high power level or interference has been detected for a given time period, the scan module 230 may switch from the fast scan mode to the normal scan mode to further confirm whether the RF signal received by the antenna 260 comprises any Bluetooth packets or noise such as interference caused by a Wi-Fi packet.

FIG. 8 shows an ID packet recognition method for a communication apparatus according to an embodiment of the invention. First, an RF signal is received via an antenna (e.g. 260) and an RF module (e.g. 210) of the communication apparatus (step S802). Next, in step S804, the RF signal is converted into an intermediary signal, e.g. a digital signal, an intermediate frequency signal or a Baseband signal. Next, in step S806, a fast scan procedure is performed by a scan module (e.g. 230) of the communication apparatus on the intermediary signal to obtain a power distribution pattern corresponding to the intermediary signal in a time domain, and to obtain a power decision result corresponding to the RF signal according to the power distribution pattern. Next, in step S808, a subsequent process is performed according to the power decision result obtained in step S806. For example, if the power decision result indicates that the power distribution pattern matches a Bluetooth ID pattern (e.g. P1 or P2 of FIG. 4), the communication apparatus may establish a link with the peer Bluetooth device based on the ID packet. If the power decision result indicates that the power distribution pattern matches a noise/interference ID pattern (e.g. P3 or P4 of FIG. 5), the communication apparatus may determine that the RF signal has noise interference or the RF signal does not comprise any Bluetooth ID packets. Thus, the communication apparatus may continue performing the fast scan procedure periodically to monitor the power distribution pattern corresponding to the intermediary signal in a time domain. If the power decision result indicates that no power or low power has been detected in the power distribution pattern for a given time period (e.g. P5-P8 of FIG. 6), the communication apparatus may stop performing the fast scan procedure and then start to perform a normal scan procedure to further confirm whether the RF signal comprises any Bluetooth ID packets. If the power decision result indicates that high power level has been detected in the power distribution pattern (e.g. P9 of FIG. 7), the communication apparatus may stop performing the fast scan procedure and then start to perform a normal scan procedure to further confirm whether the RF signal comprises a plurality of Bluetooth ID packets or has noise interference caused by a Wi-Fi packet. Therefore, by performing the fast scan procedure of the invention, a communication apparatus can determine whether an ID packet exists faster; thus reducing power consumption. Furthermore, high detection rate and low false alarm rate are obtained for page and inquiry scans in a Bluetooth compatible network.

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A communication apparatus, comprising:

an RF module, for receiving an RF signal and generating an intermediary signal corresponding to the RF signal; and

a scan module, coupled to the RF module, for recognizing a time-domain pattern corresponding to the intermediary signal, and determining whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

2. The communication apparatus as claimed in claim 1, wherein the scan module compares the recognized time-domain pattern with a predefined ID pattern, and determines that the RF signal comprises the ID packet when the comparison result indicates that the recognized time-domain pattern matches the predefined ID pattern.

3. The communication apparatus as claimed in claim 1, wherein the time-domain pattern comprises a power distribution pattern of the intermediary signal, and the scan module comprises:

a power detection unit, coupled to the RF module, for detecting power level of the intermediary signal during a specific time period to generate the power distribution pattern of the intermediary signal; and

a packet recognition unit, coupled to the power detection unit, for determining whether the RF signal comprises the ID packet according to the power distribution pattern.

4. The communication apparatus as claimed in claim 3, wherein the power distribution pattern comprises N bits, the specific time period comprises N sub-periods, and each of the N bits indicates the power level of the intermediary signal during a corresponding sub-period within the specific time period.

5. The communication apparatus as claimed in claim 4, wherein each bit with a first logic level is used to indicate that the power level of the intermediary signal during the corresponding sub-period has exceeded a threshold value, and each bit with a second logic level different to the first logic level is used to indicate that the power level of the intermediary signal during the corresponding sub-period has not exceeded the threshold value.

6. The communication apparatus as claimed in claim 5, wherein the power distribution pattern matches a predefined Bluetooth ID pattern when two bits with the first logic level of the power distribution pattern are separated by a time interval close to 312.5 μs or 937.5 μs.

7. The communication apparatus as claimed in claim 5, wherein the power distribution pattern does not match a predefined Bluetooth ID pattern when the number of continuous bits with the first logic level of the power distribution pattern is larger than or equal to a specific value.

8. The communication apparatus as claimed in claim 5, wherein the power distribution pattern does not match a predefined Bluetooth ID pattern when the number of continuous separation groups of the power distribution pattern is larger than or equal to a specific value, wherein each of the separation groups is composed of a first bit with the first logic level and one or more second bits with the second logic level which is/are subsequent to the first bit.

9. The communication apparatus as claimed in claim 3, further comprising:

an analog-to-digital converter, coupled between the power detection unit and the packet recognition unit, for sampling the power distribution pattern of the intermediary signal to generate a plurality of sampling results;

wherein the packet recognition unit determines whether the RF signal comprises the ID packet according to the plurality of sampling results.

10. The communication apparatus as claimed in claim 1, further comprising:

an analog-to-digital converter, coupled between the RF module and the scan module, for sampling the intermediary signal to generate a plurality of sampling results;

wherein the scan module recognizes the time-domain pattern corresponding to the intermediary signal based on the plurality of sampling results.

11. The communication apparatus as claimed in claim 1, implemented to recognize a Bluetooth ID packet, and when the scan module determines that the RF signal comprises an ID packet sent by a peer Bluetooth apparatus, the communication apparatus is configured to establish a link with the peer Bluetooth apparatus based on the ID packet.

12. A communication apparatus, comprising:

an RF module, for receiving an RF signal; and

a scan module, coupled to the RF module and having at least two scan modes comprising a fast scan mode and a normal scan mode, wherein when operating in the fast scan mode, the scan module recognizes a time-domain pattern corresponding to the RF signal and determines whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

13. The communication apparatus as claimed in claim 12, wherein the scan module compares the recognized time-domain pattern with a predefined ID pattern, and determines that the RF signal comprises the ID packet when the comparison result indicates that the recognized time-domain pattern matches the predefined ID pattern.

14. The communication apparatus as claimed in claim 12, wherein the scan module switches from the fast scan mode to the normal scan mode when the time-domain pattern corresponding to the RF signal indicates that no power or low power level has been detected for a given time period.

15. The communication apparatus as claimed in claim 12, wherein the scan module switches from the fast scan mode to the normal scan mode when the time-domain pattern corresponding to the RF signal indicates that high power level or interference has been detected for a given time period.

16. A method for recognizing an ID packet comprised in an RF signal, comprising:

receiving an RF signal and generating an intermediary signal corresponding to the RF signal; and

performing a fast scan procedure, comprising: recognizing a time-domain pattern corresponding to the intermediary signal; and determining whether the RF signal comprises an ID packet according to the recognized time-domain pattern.

17. The method as claimed in claim 16, wherein the determining step comprises:

comparing the recognized time-domain pattern with a predefined ID pattern; and

determining that the RF signal comprises the ID packet when the comparison result indicates that the recognized time-domain pattern matches the predefined ID pattern.

18. The method as claimed in claim 16, wherein the time-domain pattern comprises a power distribution pattern of the intermediary signal, the step of recognizing the time-domain pattern corresponding to the intermediary signal comprises: and the step of determining whether the RF signal comprises the ID packet comprises:

detecting the power level of the intermediary signal during a specific time period to generate the power distribution pattern of the intermediary signal;

determining whether the RF signal comprises the ID packet according to the power distribution pattern.

19. The method as claimed in claim 18, wherein the power distribution pattern comprises N bits, the specific time period comprises N sub-periods, and each of the N bits indicates the power level of the intermediary signal during a corresponding sub-period within the specific time period.

20. The method as claimed in claim 16, further comprising:

performing a normal scan procedure when the recognized time-domain pattern corresponding to the intermediary signal indicates that no power or low power level has been detected for a given time period.

21. The method as claimed in claim 16, further comprising:

performing a normal scan procedure when the recognized time-domain pattern corresponding to the intermediary signal indicates that high power level or interference has been detected for a given time period.