WO2013097743A1

WO2013097743A1 - Communications apparatuses and methods for avoiding interference in communications apparatus

Info

Publication number: WO2013097743A1
Application number: PCT/CN2012/087665
Authority: WO
Inventors: Wei-Cheng Liu; Wen-Wei Yang; Yen-Po LEE; Shan-Chi YANG
Original assignee: Mediatek Inc.
Priority date: 2011-12-29
Filing date: 2012-12-27
Publication date: 2013-07-04
Also published as: CN104025530B; CN104025530A

Abstract

A communications apparatus includes a baseband module, a radio transceiver module, a front- end signal processing module and an antenna switch module. The front-end signal processing module is coupled to the radio transceiver module and pre-processes RF signals received from at least one antenna to generate pre-processed RF signals. The front-end signal processing module includes at least a first bandpass filter and a second bandpass filter. A frequency range of a first passband of the first bandpass filter overlaps with a frequency range of a second passband of the second bandpass filter, and the frequency range of the second passband is wider than the frequency range of the first passband.

Description

COMMUNICATIONS APPARATUSES AND METHODS FOR AVOIDING INTERFERENCE IN COMMUNICATIONS APPARATUS

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/581,336 filed 2011/12/29. The entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The invention relates to a multi-radio coexistence system, and more particularly, to a multi- radio coexistence system with efficient interference avoidance.

BACKGROUND

With the development of wireless communications technology, mobile electronic devices may be provided with more than one wireless communications service, such as Bluetooth, Wireless Fidelity (WiFi), Global System for Mobile Communications (GSM), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), and so on. In this regard, the overlapping operating frequency band or adjacent operating frequency band among the different wireless communications services causes transmission performances thereof to degrade. For example, when the transmitting (TX) signals are transmitted in a frequency band that is overlapped with or adjacent to a frequency band receiving (RX) signals, the TX signals transmitted by one antenna may be captured by the other antenna utilized for receiving the RX signals, causing undesired interference.

The undesired interference seriously degrades the integrity of the RX signals since the two antennas are disposed very close to each other and the TX power is generally much higher than the RX power.

Therefore, a multi-radio coexistence system with efficient interference avoidance is highly desired.

SUMMARY

Communications apparatuses and methods for avoiding interference in a communications apparatus are provided. An exemplary embodiment of a communications apparatus is provided, and comprises a baseband module, a radio transceiver module, a front-end signal processing module and an antenna switch module. The baseband module processes a plurality of baseband signals. The radio transceiver module is coupled to the baseband module and processes a plurality of pre- processed radio frequency (RF) signals. The front-end signal processing module is coupled to the radio transceiver module and pre-processes a plurality of RF signals received from at least one antenna to generate the pre-processed RF signals. The antenna switch module is coupled between the front-end signal processing module and the at least one antenna for selectively passing the RF signals received from the at least one antenna to one of a plurality of pre-processing paths provided by the front-end signal processing module. The front-end signal processing module comprises at least a first bandpass filter and a second bandpass filter disposed on the plurality of pre-processing paths. A frequency range of a first passband of the first bandpass filter overlaps with a frequency range of a second passband of the second bandpass filter, and the frequency range of the second passband is wider than the frequency range of the first passband.

Another exemplary embodiment of a communications apparatus is provided, and comprises a baseband module, a radio transceiver module, a front-end signal processing module and an antenna switch module. The baseband module processes a plurality of baseband signals. The radio transceiver module is coupled to the baseband module and processes a plurality of pre-processed radio frequency (RF) signals. The front-end signal processing module is coupled to the radio transceiver module and pre-processes a plurality of RF signals received from at least one antenna to generate the pre-processed RF signals. The antenna switch module is coupled between the front-end signal processing module and the at least one antenna for selectively passing the RF signals received from the at least one antenna to one of a plurality of pre-processing paths provided by the front-end signal processing module. At least one of the pre-processing paths is utilized for filtering the RF signals according to a tunable frequency response with a passband having a bandwidth that is tunable. The bandwidth is tuned between a first frequency range and a second frequency range in response to a control signal issued by the baseband module, and the first frequency range overlaps with the second frequency range and is narrower than the second frequency range.

An exemplary embodiment of a method for avoiding interference in a communications apparatus comprising at least one pre-processing path coupled between an antenna and a radio transceiver module and utilized for filtering a plurality of RF signals received from the antenna is provided, and comprises: determining whether a receiving channel of the RF signals falls within a first frequency range; using a filter having a first passband in the first frequency range for filtering the RF signals when the receiving channel of the RF signals falls within the first frequency range; and using a filter having a second passband in a second frequency range for filtering the RF signals when the receiving channel of the RF signals does not fall within the first frequency range, wherein the second frequency range partially overlaps with the first frequency range and is wider than the first frequency range.

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 is a frequency spectrum showing some exemplary operating frequency bands of different RATs;

FIG. 2 is a block diagram showing a communications apparatus according to an embodiment of the invention;

FIG. 3 is a block diagram showing a portion of a communications apparatus according to a first embodiment of the invention;

FIG. 4 shows two frequency responses with different passband bandwidths according to an embodiment of the invention;

FIG. 5 is a block diagram showing a portion of a communications apparatus according to a second embodiment of the invention;

FIG. 6 shows a block diagram of a portion of a communications apparatus according to a third embodiment of the invention;

FIG. 7 shows two frequency responses with different passband bandwidths according to another embodiment of the invention;

FIG. 8 shows two frequency responses with different passband bandwidths according to yet another embodiment of the invention; and

FIG. 9 shows a flow chart of a method for avoiding interference in a communications apparatus.

DETAILED DESCRIPTION

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.

As discussed above, mobile electronic devices, such as communications apparatuses, are now capable of supporting multiple radio access technologies (RATs) communications and therefore, are capable of providing more than one wireless communications service. Thus, enhanced, multi- standby, or even multi-talk communications apparatuses have also been development. Therefore, different RAT modules coexisting in one communications apparatus may transmit and/or receive radio frequency (RF) signals at the same time. However, when one RAT module with operating frequency bands adjacent to or overlapping with that of other RATs, is transmitting TX signals, the TX signal may be captured by another coexisting RAT module receiving RX signals at the same time, causing undesired interference. The undesired interference seriously degrades the integrity of RX signals since the two antennas (or antenna arrays) coexisting in one communications apparatus are disposed very close to each other and the TX power is generally much higher than the RX power.

FIG. 1 is a frequency spectrum showing some exemplary operating frequency bands of different RATs, where the X-axis represents the frequency and the Y-axis represents the transmit (TX) or receive (RX) power requirement defined by the corresponding specifications. GSM-TX represents the TX bands of the GSM-900 system, and GSM-RX represents the RX bands of the GSM-900 system. Digital Cellular Service (DCS)-TX represents the TX bands of the GSM- 1800 system, and DCS-RX represents the RX bands of the GSM- 1800 system. TD-B39 represents the operating frequency bands of the Time Division-Synchronous Code Division Multiple Access (TD- SCDMA) band 39, and TD-B34 represents the operating frequency bands of the TD-SCDMA band 34. TD-LTE-B40 represents the operating frequency bands of the TD-LTE band 40, and TD-LTE- B38 represents the operating frequency bands of the TD-LTE band 38. WiFi-B represents the operating frequency bands of the WiFi.

As shown in FIG. 1, since the DCS-RX ranges from 1805MHz to 1880MHz and the TD-B39 ranges from 1880MHz to 1920MHz, there is no guard band disposed between the DCS-RX band and TD-SCDMA band 39. Therefore, serious interference may occur when the TX signals of the TD-SCDMA band 39 leak to the DCS-RX band (i.e. captured by the DCS receiving antenna), which if so, would cause the performance of the DCS RX to degrade. Also, since the WiFi operating frequency bands ranges from 2400MHz to 2483.5MHz and the TD-LTE band 40 ranges from 2300MHz to 2400MHz, there is no guard band disposed between the WiFi operating frequency band and TD-LTE band 40. Therefore, interference may also occur when the TX signals of a WiFi or TD-LTE band 40 leak to the TD-LTE band 40 or WiFi operating frequency band (i.e. captured by the receiving antenna of the other RAT), which if so, would cause the performance of both the WiFi and TD-LTE band 40 RX performance to degrade.

To avoid the undesired interference in multi-radio coexistence systems, a communications apparatus and methods for solving the above-mentioned problems are proposed in the following paragraphs.

FIG. 2 is a block diagram showing a communications apparatus according to an embodiment of the invention. The communications apparatus 100 may support at least two different RAT communications, and may comprise baseband modules 110 and 210, radio transceiver modules 120 and 220, front-end signal processing modules 130 and 230, antenna switch modules 140 and 240, and antennas ANT 1 and ANT 2. The baseband modules 110 and 210 may respectively be arranged for processing baseband signals. The baseband modules 110 and 210 may convert the baseband signals to a plurality of digital signals, and process the digital signals, and vice versa. The baseband modules 110 and 210 may respectively comprise a plurality of hardware devices to perform baseband signal processing. The baseband signal processing may comprise analog to digital conversion (ADC)/digital to analog conversion (DAC), gain adjustment, modulation/demodulation, encoding/decoding, and so on. The baseband modules 110 and 210 may further respectively comprise a memory device and a processor for respectively controlling the operations of the corresponding baseband module, radio transceiver module, front-end signal processing module and antenna switch module for the same RAT. In some embodiments, the baseband modules 110 and 210 may also communicate with each other via an interface 150 connected therebetween.

The radio transceiver modules 120 and 220 may respectively receive pre-processed RF signals, convert the received signals to baseband signals to be processed by the baseband modules 110 and 210, or respectively receive baseband signals from the baseband modules 110 and 210 and convert the received signals to RF signals to be transmitted. The radio transceiver modules 120 and 220 may comprise a plurality of hardware devices to perform radio frequency conversion. For example, the radio transceiver modules 120 and 220 may respectively comprise a mixer to multiply the baseband signals with a carrier oscillated in a predetermined radio frequency, depending on the RAT in used.

The front-end signal processing modules 130 and 230 may respectively pre-process the RF signals received from the antennas ANT1 and ANT2 to generate the pre-processed RF signals, or post-process the RF signals received from the radio transceiver modules 120 and 220 before the RF signals are passed to the antennas ANT1 and ANT2. The front-end signal processing modules 130 and 230 may respectively provide one or more pre-processing paths for pre-processing the RF signals received from the antennas ANT1 and ANT2 and one or more post-processing paths for post-processing RF signals received from the radio transceiver modules 120 and 220. According to an embodiment of the invention, the front-end signal processing modules 130 and 230 may respectively comprise one or more bandpass filters for filtering the RF signals received from the antennas ANT1 and ANT2, and one or more power amplifiers for further amplifying the RF signals received from the radio transceiver modules 120 and 220.

The antenna switch modules 140 and 240 may be respectively coupled between the front-end signal processing module and the antenna for passing the RF signals received from the front-end signal processing module to the antenna and selectively passing the RF signals received from the corresponding antenna to one of the plurality of pre-processing paths provided by the front-end signal processing modules 130 and 230 under the control of the baseband modules 110 and 210 (e.g. the processor). For example, when the currently received RX signals are DCS RX signals, the antenna switch modules 140 and/or 240 may pass the currently received RX signals to a pre- processing path designated for processing the DCS RX signals.

Note that in some embodiments of the invention, the baseband module 110, the radio transceiver module 120, the front-end signal processing module 130, the antenna switch module 140, and the antenna ANT 1 may be comprised in one RAT module or one chip, and the baseband module 210, the radio transceiver module 220, the front-end signal processing module 230, the antenna switch module 240, and the antenna ANT 2 may be comprised in another different RAT module or another chip. In some other embodiments of the invention, the baseband modules 110 and 210, the radio transceiver modules 120 and 220, the front-end signal processing modules 130 and 230, the antenna switch modules 140 and 240, and the antennas ANT 1 and ANT 2 may also be integrated in the same module or the same chip. In still some other embodiments of the invention, the baseband modules 110 and 210 and/or the radio transceiver modules 120 and 220 may be integrated as only one baseband module and/or only one radio transceiver module. In yet some other embodiments of the invention, the baseband modules 110 and the radio transceiver module 120 may be integrated as one module or one chip, as well as the baseband modules 210 and the radio transceiver module 220. Those who are skilled in this technology can still make various alterations and modifications based on FIG. 2 without departing from the scope and spirit of this invention. Therefore, the invention should not be limited to the architecture as shown in FIG. 2.

As discussed above, the front-end signal processing module (e.g. the front-end signal processing module 130 and/or 230) may provide one or more pre-processing paths for preprocessing the RF signals received from the antenna. According to an embodiment of the invention, at least one of the pre-processing paths may be utilized for filtering the RF signals according to a tunable frequency response with a passband having a bandwidth that is tunable, so as to filter out possible interference caused by the TX signals transmitted in adjacent or overlapping frequency bands, which are captured by the antenna.

FIG. 3 shows a block diagram of a portion of a communications apparatus according to a first embodiment of the invention. Note that for brevity, the baseband module is omitted in FIG. 3. As shown in FIG. 3, the front-end signal processing module 330 (which may be either or both of the front-end signal processing modules 130 and 230 in FIG. 2) is coupled between the radio transceiver module 320 and antenna switch module 340. The front-end signal processing module 330 may comprise a plurality of filters 331~33n for pre-processing the RF signals captured by the antenna ANT and a plurality of power amplifier (PA) for post-processing the RF signals to be passed to the antenna ANT. The filters 331~33n may be bandpass filters and may be designated for filtering the RF signals transmitted in a predetermined frequency band of a predetermined RAT, for example, the GSM RX band, DCS RX band, TD-SCDMA band 39, TD-LTE band 40, WiFi, or others.

According to the first embodiment of the invention, at least two filters, such as the filters 332 and 333 as shown in FIG. 3, with overlapping passbands may be designated for filtering the RF signals transmitted in the same frequency band of the same RAT. The two filters with overlapping passbands may be designated for filtering the RF signals of the RAT, such as the GSM-1800 (DCS), TD-LTE band 40 or WiFi as shown in FIG. 1, or others, which may possibly be influenced with interference by the TX signals transmitted in the adjacent frequency bands with no guard band or only a small guard band. According to the first embodiment of the invention, the filters 332 and 333 may be alternatively activated for filtering the RF signals in response to a control signal issued by the baseband module (not shown). For example, the baseband module (not shown) may issue the control signal to control the antenna switch module 340 to pass the RF signals received from the antenna ANT to one of the filters 332 and 333. In this manner, only one the pre-processing path 350 may be contributed by the filters 332 and 333 and the pre-processing path 350 may be utilized for filtering the RF signals according to a tunable frequency response with a passband having a bandwidth that is tunable (for example, tuned between the frequency ranges of the passbands of the filters 332 and 333).

In one embodiment, a frequency range of the passband of the filter 332 may be overlapping with a frequency range of the passband of the filter 333, and the frequency range of the passband of the filter 332 may be designed to be narrower than the frequency range of the passband of the filter 333, so as to filter out undesired interference. Note that a passband is defined as the range of frequencies that can pass through a filter without being attenuated (i.e. almost OdB attenuation).

Although a block diagram on the primary paths (including both the receiving and transmitting paths) of a communications apparatus is shown in FIG. 3, the invention should not be limited thereto. Note that the concept of using such a bandpass filter to filter out undesired interference as discussed above may also be applied on the diversity path(s) (including only the receiving path(s)). FIG. 4 shows two frequency responses with different passband bandwidths according to an embodiment of the invention, where the X-axis represents the frequency and the Y-axis represents the insertion attenuation. The frequency response 420 may have a wider passband bandwidth while the frequency response 410 may have a narrower passband bandwidth. Suppose that in the example, the filters 332 and 333 are utilized for pre-processing the DCS RX signals and the frequency response 420 may be the frequency response of filter 333 and the frequency response 410 may be the frequency response of filter 332. Therefore, as shown in FIG. 4, a frequency range of a passband of the filter 333 may begin from 1805MHz to 1880MHz and a frequency range of a passband of the filter 332 may begin from 1805MHz to 1850MHz. Note further that in this embodiment, the passband bandwidth of filter 332 is 30 MHz narrower than the passband bandwidth of filter 333, so as to filter out undesired interference caused by the TD-B39 TX signals. Note that except for sacrifice spectrum utilization, applying such a bandpass filter to filter out undesired interference will not cause any negative impact since a network provider (such as. an operator) usually does not use up all the frequencies in a predetermined frequency band. The frequency range of filter's passband may be determined according to the frequency band usage of various national/geographic location, quality of signal, or the level of signal degrading sensitivity.

According to an embodiment of the invention, the frequency range of the passband of the filter 332 may also be completely covered by the frequency range of the passband of the filter 333, such as the frequency responses 410 and 420 shown in FIG. 4. Note that although the filters 331~33n as shown in FIG. 3 output differential signals, the invention should not be limited thereto. For example, depending on the port number and port type of the radio transceiver module 320, the filters 331~33n may also output single-ended pre-processed RF signals.

FIG. 5 shows a block diagram of a portion of a communications apparatus according to a second embodiment of the invention. Note that for brevity, the baseband module is omitted in FIG. 5. As shown in FIG. 5, the front-end signal processing module 530 (which may be either or both of the front-end signal processing modules 130 and 230 in FIG. 2) is coupled between the radio transceiver module 520 and antenna switch module 540. The front-end signal processing module 530 may comprise a plurality of filters 531~53n for pre-processing the RF signals captured by the antenna ANT and a plurality of power amplifier (PA) for post-processing the RF signals to be passed to the antenna ANT. The filters 531~53n may be bandpass filters and may be designated for filtering the RF signals transmitted in a predetermined frequency band of a predetermined RAT, for example, the GSM RX band, DCS RX band, TD-SCDMA band 39, TD-LTE band 40, WiFi, or others.

According to the second embodiment of the invention, at least two filters, such as the filters 532 and 533 as shown, with overlapping passbands may be designated for filtering the RF signals transmitted in the same frequency band of the same RAT. The two filters with overlapping passbands may be designated for filtering the RF signals of the RAT, such as the GSM-1800 (DCS), TD-LTE band 40 or WiFi as shown in FIG. 1, or others, which may possibly be influenced with interference by the TX signals transmitted in the adjacent frequency bands with no guard band or only a small guard band. In one embodiment, a frequency range of a passband of the filter 532 may be overlapping with a frequency range of a passband of the filter 533, and the frequency range of the passband of the filter 532 may be designed to be narrower than the frequency range of the passband of the filter 533, so as to filter out undesired interference.

According to the second embodiment of the invention, the filters 532 and 533 may be alternatively activated for filtering the RF signals in response to a control signal issued by the baseband module (not shown). For example, the baseband module (not shown) may issue the control signal to control the antenna switch module 540 to pass the RF signals received from the antenna ANT to one of the filters 532 and 533. In addition, the front-end signal processing module 530 may further comprise a switch 560 coupled to the filters 532 and 533 for selectively passing the pre-processed RF signals generated by the filter 532 or 533 to the radio transceiver module 520 in response to a switch command SW issued by the baseband module (not shown). In this manner, only one pre-processing path 550 may be contributed by the filters 532 and 533 and the preprocessing path 550 may be utilized for filtering the RF signals according to a tunable frequency response with a passband having a bandwidth that is tunable (for example, tuned between the frequency ranges of the passbands of the filters 532 and 533).

The baseband module may issue the switch command every time the RF signals transmitted in the predetermined frequency band of the predetermined RAT that are designated to be processed by the filters 532 or 533 are to be received. The switch 560 may be a double-pole, four-throw (DP4T) switch. Note that although the filters 531~53n as shown in FIG. 5 output differential signals, the invention should not be limited thereto. For example, depending on the port number and port type of the radio transceiver module 520, the filters 531~33n may also output single-ended pre-processed RF signals.

Although a block diagram on the primary paths (including both the receiving and transmitting paths) of a communications apparatus is shown in FIG. 5, the invention should not be limited thereto. Note that the concept of using such a bandpass filter to filter out undesired interference as discussed above may also be applied on the diversity path(s) (including only the receiving path(s)).

FIG. 6 shows a block diagram of a portion of a communications apparatus according to a third embodiment of the invention. Note that for brevity, the baseband module is omitted in FIG. 6. As shown in FIG. 6, the front-end signal processing module 630 (which may be either or both of the front-end signal processing modules 130 and 230 in FIG. 2) is coupled between the radio transceiver module 620 and antenna switch module 640. The front-end signal processing module 630 may comprise at least one tunable bandpass filter, such as the filter 631, having a tunable frequency response. For example, a passband bandwidth of the tunable bandpass filter may be tuned between at least a first frequency range and a second frequency range. According to an embodiment of the invention, the first frequency range may be overlapping with the second frequency range and narrower than the second frequency range, so as to filter out undesired interference. According to another embodiment of the invention, the first frequency range may be completely covered by the second frequency range.

Note that although the filters 631~63n as shown in FIG. 6 output differential signals, the invention should not be limited thereto. For example, depending on the port number and port type of the radio transceiver module 620, the filters 631~63n may also output single-ended pre-processed RF signals.

Note further that although a block diagram on the primary paths (including both the receiving and transmitting paths) of a communications apparatus is shown in FIG. 6, the invention should not be limited thereto. Note that the concept of using such a bandpass filter to filter out undesired interference as discussed above may also be applied on the diversity path(s) (including only the receiving path(s)).

Note further that although the DCS RX band, which may possibly be influenced with interference by the TX signals transmitted in TD-SCDMA band 39, is taken as examples in the embodiments discussed above, the invention should not be limited thereto. FIG. 7 shows two frequency responses with different passband bandwidths according to another embodiment of the invention, where the X-axis represents the frequency and the Y-axis represents the insertion attenuation. The frequency response 720 may have a wider passband bandwidth while the frequency response 710 may have a narrower passband bandwidth. In this embodiment, the frequency responses 710 and 720 may be adopted by two bandpass filters or one tunable bandpass filter disposed on a pre-processing path utilized for filtering TD-LTE band 40 RF signals. When the bandpass filter having the frequency response 710 is activated (or the frequency response of the tunable bandpass filter is tuned to the frequency response 710), the bandpass filter having the frequency response 710 can filter out interference caused by WiFi TX signals, so as to improve the TD-LTE band 40's RX performance. Note that the range of frequencies for filter's passband may be determined according to the frequency band usage of various national/geographic location, quality of signal, or the level of signal degrading sensitivity. FIG. 8 shows two frequency responses with different passband bandwidths according to yet another embodiment of the invention, where the X-axis represents the frequency and the Y-axis represents the insertion attenuation. The frequency response 820 may have a wider passband bandwidth while the frequency response 810 may have a narrower passband bandwidth. In this embodiment, the frequency responses 810 and 820 may be adopted by two bandpass filters or one tunable bandpass filter disposed on a pre-processing path utilized for filtering WiFi RF signals. When the bandpass filter having the frequency response 810 is activated (or the frequency response of the tunable bandpass filter is tuned to the frequency response 810), the bandpass filter having the frequency response 810 can filter out interference caused by TD-LTE band 40 TX signals so as to improve the WiFi's RX performance. Note that except for sacrifice spectrum utilization, applying such a bandpass filter to filter out undesired interference will not cause any negative impact since a network provider (such as. an operator) usually does not use up all the frequencies in a predetermined frequency band.

FIG. 9 shows a flow chart of a method for avoiding interference in a communications apparatus. In the embodiment, every time when a receiving process begins (i.e. the RF signals transmitted in a predetermined frequency band of a predetermined RAT are to be received) (Step S901), the baseband module (or the processor) may first determine whether a receiving channel of the RF signals falls within a first frequency range (Step S902). When the receiving channel of the RF signals falls within the first frequency range, a filter having a first passband in the first frequency range is used for filtering the RF signals (Step S903). Otherwise, a filter having a second passband in a second frequency range is used for filtering the RF signals (Step S904). After selecting the filter for filtering the RF signals, the RF signals are received (Step S905). After all of the RF signals scheduled to be received have been received, the receiving process is finished (Step S906). The baseband module (or the processor) may further determine whether another receiving process should begin (Step S907), and the process returns to step S901 when a receiving process is required to begin.

Note that in the embodiment, the second frequency range partially overlaps with the first frequency range and is wider than the first frequency range. To be more specific, the second frequency range may be designed as a full band of the predetermined frequency band of the predetermined RAT, while the first frequency range may be designed as a partial band of the predetermined frequency band of the predetermined RAT. For example, when the predetermined frequency band of the predetermined RAT having RX signals to be received is GSM band 1800 (that is, the DCS), a full band of GSM band 1800 may range from 1805MHz to 1880MHz and a partial band of GSM band 1800 may range from 1805MHz to 1850MHz. Therefore, the second passband may be designed to span from 1805MHz to 1880MHz, while the first passband may be designed to span from 1805MHz to 1850MHz.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. Those who are skilled in this technology can still make various alterations and modifications without departing from the scope and spirit of this invention. Therefore, the scope of the present invention shall be defined and protected by the following claims and their equivalents.

Claims

1. A communications apparatus, comprising:

a baseband module, processing a plurality of baseband signals;

a radio transceiver module, coupled to the baseband module and processing a plurality of pre- processed radio frequency (RF) signals;

a front-end signal processing module, coupled to the radio transceiver module and preprocessing a plurality of RF signals received from at least one antenna to generate the pre-processed RF signals;

an antenna switch module, coupled between the front-end signal processing module and the at least one antenna for selectively passing the RF signals received from the at least one antenna to one of a plurality of pre-processing paths provided by the front-end signal processing module,

wherein the front-end signal processing module comprises at least a first bandpass filter and a second bandpass filter disposed on the plurality of pre-processing paths, and

wherein a frequency range of a first passband of the first bandpass filter overlaps with a frequency range of a second passband of the second bandpass filter, and the frequency range of the second passband is wider than the frequency range of the first passband.

2. The communications apparatus as claimed in claim 1, wherein the first bandpass filter and the second bandpass filter are designate for filtering the RF signals transmitted in the same frequency band of the same radio access technology (RAT).

3. The communications apparatus as claimed in claim 1, wherein the frequency range of the first passband is completely covered by the frequency range of the second passband.

4. The communications apparatus as claimed in claim 1, wherein the front-end signal processing module further comprises a switch coupled to the first bandpass filter and the second bandpass filter for selectively passing the pre-processed RF signals generated by the first bandpass filter or the second bandpass filter to the radio transceiver module in response to a switch command issued by the baseband module.

5. The communications apparatus as claimed in claim 4, wherein the baseband module issues the switch command every time the RF signals transmitted in a predetermined frequency band of a predetermined radio access technology (RAT) are to be received.

6. A communications apparatus, comprising:

a baseband module, processing a plurality of baseband signals;

a radio transceiver module, coupled to the baseband module and processing a plurality of pre- processed radio frequency (RF) signals; a front-end signal processing module, coupled to the radio transceiver module and preprocessing a plurality of RF signals received from at least one antenna to generate the pre-processed RF signals;

wherein at least one of the pre-processing paths is utilized for filtering the RF signals according to a tunable frequency response with a passband having a bandwidth that is tunable, wherein the bandwidth is tuned between a first frequency range and a second frequency range in response to a control signal issued by the baseband module, and

wherein the first frequency range overlaps with the second frequency range and is narrower than the second frequency range.

7. The communications apparatus as claimed in claim 6, wherein the front-end signal processing module comprises:

a first bandpass filter, having a first passband in the first frequency range; and

a second bandpass filter, having a second passband in the second frequency range.

8. The communications apparatus as claimed in claim 7, wherein the first bandpass filter and the second bandpass filter are disposed on the at least one of the pre-processing paths and are alternatively activated for filtering the RF signals in response to the control signal.

9. The communications apparatus as claimed in claim 7, wherein the front-end signal processing module further comprises a switch coupled to the first bandpass filter and the second bandpass filter for selectively passing the pre-processed RF signals generated by the first bandpass filter or the second bandpass filter to the radio transceiver module in response to a switch command issued by the baseband module.

10. The communications apparatus as claimed in claim 6, wherein the front-end signal processing module comprises:

a tunable bandpass filter, disposed on the at least one of the pre-processing paths and having a passband bandwidth that is tuned between the first frequency range and the second frequency range.

11. The communications apparatus as claimed in claim 6, wherein the first frequency range is completely covered by the second frequency range.

12. A method for avoiding interference in a communications apparatus comprising at least one pre-processing path coupled between an antenna and a radio transceiver module and utilized for filtering a plurality of RF signals received from the antenna, the method comprising:

determining whether a receiving channel of the RF signals falls within a first frequency range; using a filter having a first passband in the first frequency range for filtering the RF signals when the receiving channel of the RF signals falls within the first frequency range; and

using a filter having a second passband in a second frequency range for filtering the RF signals when the receiving channel of the RF signals does not fall within the first frequency range,

wherein the second frequency range partially overlaps with the first frequency range and is wider than the first frequency range.

13. The method as claimed in claim 12, wherein the first frequency range is completely covered by the second frequency range.

14. The method as claimed in claim 12, wherein the filter having the first passband and the filter having the second passband are designate for filtering the RF signals transmitted in the same frequency band of the same radio access technology (RAT).

15. The method as claimed in claim 14, wherein the RAT is GSM- 1800, TD-LTE or WiFi.