Abstract:
A wireless communications includes a first wireless communications and a second wireless communications. The first wireless communications module transmits or receives a first wireless signal in a first frequency band selected from a first frequency range. The second wireless communications module transmits or receives a second wireless signal in a second frequency band selected from a second frequency range, and adjusts a transmission power of the second wireless signal in response to that a frequency offset between the first frequency band and the second frequency band falls within a predetermined range. The first wireless communications module is further configured to determine an in-band range in the overlapping part of the first and second frequency ranges, and a transmission power of the second wireless signal is adjusted in response to a frequency offset between the first frequency band and the second frequency band.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of pending U.S. patent application Ser. No. 12/829,943, filed on Jul. 2, 2010, which claims the benefit of U.S. Provisional Application No. 61/224,107, filed on Jul. 9, 2009, the entirety of which is incorporated by reference herein; and U.S. Provisional Application No. 61/298,627, filed on Jan. 27, 2010, the entirety of which is incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates generally to the coexistence between a plurality of wireless communications modules, and more particularly, to systems and methods for the reducing interference between a plurality of co-existed wireless communications modules. 
         [0004]    2. Description of the Related Art 
         [0005]    To an increasing extent, a multitude of communication functions are being merged into mobile devices. As shown in  FIG. 1 , a cellular phone may connect to a wireless local area network (WLAN) via a Wireless Fidelity (WiFi) module thereof and simultaneously communicate with a Bluetooth (BT) handset (or a Bluetooth car audio, or others) through a Bluetooth module thereof. A WLAN system is typically implemented inside buildings as an extension to wired local area networks (LANs) and is able to provide the last few meters of connectivity between a wired network and mobile or fixed devices. According to the IEEE 802.11 standard, most WLAN systems may operate in the 2.4 GHz license-free frequency band and have very low throughput rates because of the coexistence interference from BT. Referring to  FIG. 1 , a WLAN is established by an access point (AP) connecting to a LAN by an Ethernet cable. The AP typically receives, buffers, and transmits data between the WLAN and the wired network infrastructure. The AP may support, on average, twenty devices and have a coverage varying from 20 meters in an area with obstacles (walls, stairways, elevators etc) to 100 meters in an area with clear line of sight. Bluetooth is an open wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). The cellular phone may receive the voice over internet protocol (VoIP) data via the WiFi module and further transmit the VoIP data through an established PAN to the Bluetooth handset, and vice versa. Alternatively, the cellular phone may transmit digital music through the established PAN to be played back in the Bluetooth handset. The WLAN and Bluetooth systems both occupy a section of the 2.4 GHz Industrial, Scientific, and Medical (ISM) band, which is 83 MHz-wide. Due to cost issues as well as space requirements for components, modern electronic devices, such as cellular phones, Ultra-Mobile PCs (UMPCs) or others, are equipped with WiFi and Bluetooth modules sharing a single antenna instead of multiple antennas. 
         [0006]    As an example shown in  FIG. 2 , a Bluetooth system uses a Frequency Hopping Spread Spectrum (FHSS) and hops between 79 different 1 MHz-wide channels in a Bluetooth spectrum. A WLAN system uses a Direct Sequence Spread Spectrum (DSSS) instead of a FHSS. A WLAN system carrier remains centered on one channel, which is 22 MHz-wide. When the WiFi module and the Bluetooth module are operating simultaneously in the same area, as shown in  FIG. 1 , the single WLAN channel, which is 22 MHz-wide, occupies the same frequency space as 22 out of 79 Bluetooth channels which are 1 MHz-wide. When a Bluetooth transmission occurs on a frequency band that falls within the frequency space occupied by an ongoing WLAN transmission, a certain level of interference may occur, depending on the signal strength thereof. Due to the fact that the WiFi module and Bluetooth module share the same spectrum and also share a single antenna, avoiding interference therebetween is required. 
         [0007]      FIG. 3  is a diagram illustrating an operation conflict which may occur between a WLAN and a Bluetooth communication services sharing a single antenna. In  FIG. 3 , the shared single antenna is switched between WLAN and Bluetooth communication services in a given time slot for transceiving data. If the Bluetooth communication service carries audio data that requires real-time transmission, for example, the Synchronous Connection-Oriented (SCO) packets, the Bluetooth communication service would have a higher priority over the WLAN communication service. In this case, when a WLAN transceiving process takes place at the same time as the real-time Bluetooth transceiving process, the time slot will be assigned to the Bluetooth transceiving process and the WLAN transceiving process will be blocked. As shown in  FIG. 3 , the WLAN receiving operation (Rx operation)  1  occurs in the time slot, while the Bluetooth communication service is idle. Therefore, the Rx operation  1  is performed without interference and an acknowledgement (ACK) message  2  is sent to the WLAN AP (such as the AP in  FIG. 1 ) as a reply message indicating that the Rx operation  1  is finished. Following the Rx operation  1 , another WLAN Rx operation  3  is performed. The Rx operation  3  is also performed without interference because the Bluetooth communication service is in the idle state. However, an ACK message  4  in response to the Rx operation  3  can not be replied to the WLAN AP, as its time slot is already assigned to the Bluetooth transmitting operation (Tx operation). Accordingly, the Rx operation  3  would be determined to have failed. In response to the failure, the WLAN AP would re-sent the data with a lower data rate in an attempt to successfully transmit data to the WLAN module of the mobile device. Unfavorably, the re-performed Rx operation  3  (denoted as  5 ), with a prolonged operation period, will be more likely to overlap with the Bluetooth transceiving process. Another data re-sent with a lower data rate than that of the prior re-sent would be further attempted, causing more overlap with the Bluetooth transceiving process than the prior attempt. As a result, WLAN throughput is highly damaged as the WLAN and Bluetooth wireless communication services sharing a single antenna. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In light of the previously described problems, there exists a need for a method and system, in which interference may be reduced between a plurality of wireless communication modules sharing a single antenna for simultaneous operations. 
         [0009]    One aspect of the invention discloses a wireless communications system, comprising a first wireless communications module and a second wireless communications module. The first wireless communications module is configured to transmit or receive a first wireless signal in a first frequency band selected from a first frequency range. The second wireless communications module is configured to transmit or receive a second wireless signal in a second frequency band selected from a second frequency range, and adjust a transmission power of the second wireless signal in response to that a frequency offset between the first frequency band and the second frequency band falls within a predetermined range. 
         [0010]    Another aspect of the invention discloses a method for reducing interference between a plurality of wireless communications modules in a wireless communications device, comprising: transmitting or receiving a first wireless signal in a first frequency band selected from a first frequency range by a first wireless communications module, and transmitting or receiving a second wireless signal in a second frequency band selected from a second frequency range by a second wireless communications module; determining whether a frequency offset between the first frequency band and the second frequency band is within a predetermined range; and adjusting a transmission power of the second wireless signal in response to that the frequency offset between the first frequency band and the second frequency band is within the predetermined range. 
         [0011]    Another aspect of the invention discloses another wireless communications system, comprising a first wireless communications module and a second wireless communications module. The first wireless communications module is configured to transmit or receive a plurality of first wireless signals. The second wireless communications module is configured to transmit or receive a plurality of second wireless signals, and adjust a transmission power of the second wireless signals in response to that a signal indicator of the first or second wireless signals meets a predetermined criterion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0013]      FIG. 1  shows a cellular phone connecting to a Wireless Local Area Network (WLAN) via a WLAN module thereof as well as communicating with a Bluetooth handset through a Bluetooth module thereof; 
           [0014]      FIG. 2  shows a diagram of Bluetooth frequency Hopping; 
           [0015]      FIG. 3  shows a diagram illustrating an operation conflict between a WLAN and a Bluetooth wireless communication services sharing a single antenna; 
           [0016]      FIG. 4  shows a diagram illustrating a system for the coexistence between two wireless communications modules sharing a single antenna in accordance with an embodiment of the invention; 
           [0017]      FIG. 5A  shows a diagram illustrating a switching device implemented by a single-pole double-thrown (SPDT) switch in accordance with an embodiment of the invention; 
           [0018]      FIG. 5B  shows a diagram illustrating a switching device implemented by a double-pole double-thrown (DPDT) switch in accordance with an embodiment of the invention; 
           [0019]      FIG. 6A  shows a connection device implemented using an attenuator in accordance with an embodiment of the invention; 
           [0020]      FIG. 6B  shows a connection device implemented using a directional coupler in accordance with an embodiment of the invention; 
           [0021]      FIGS. 7A and 7B  show the configurations of a connection device in accordance with an embodiment of the invention; 
           [0022]      FIGS. 8A to 8C  show a flowchart of the method for reducing interference between WiFi and the BT modules in accordance with an embodiment of the invention; 
           [0023]      FIGS. 9A and 9B  show exemplary power control of the WiFi and BT Tx signals to reduce in-band interference to the BT and WiFi Rx signals, respectively, in accordance with an embodiment of the invention; 
           [0024]      FIGS. 10A and 10B  show exemplary power control of the WiFi and BT Tx signals to reduce in-band interference to the BT and WiFi Rx signals, respectively, in accordance with another embodiment of the invention; 
           [0025]      FIGS. 11A to 11C  show a flowchart of the method for reducing interference between WiFi and the BT modules in accordance with another embodiment of the invention; 
           [0026]      FIGS. 12A to 12G  show a flowchart for handling the coexistence between WiFi and BT modules in accordance with an embodiment of the invention, based on the system of  FIG. 4 ; 
           [0027]      FIG. 13  shows a diagram illustrating a system for the coexistence between two wireless communications modules sharing a single antenna according to another embodiment of the invention; 
           [0028]      FIGS. 14A to 14G  show a flowchart for handling coexistence between WiFi and BT modules according to an embodiment of the invention, based on the system of  FIG. 13 ; and 
           [0029]      FIG. 15  shows a system for coexistence between a Global Positioning System (GPS) and a subsystem sharing a single antenna according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    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. 
         [0031]      FIG. 4  shows a diagram illustrating a system for the coexistence between two wireless communications modules sharing a single antenna in accordance with an embodiment of the invention. The system  400  comprises an antenna  10 , a switching device  20 , a connection device  30  and a wireless communications chipset  100 . The wireless communications chipset  100  comprises a control unit  110 , a WiFi module  120 , a BT module  130 , a separator  140 , a WiFi Tx front-end  151 , a WiFi/BT Rx front-end  152 , BT Tx front-ends  153  and  155 , a BT Rx front-end  154 , a balun unit  161 , and balun-switch units  162  and  163 . Each of the balun unit  161  and the balun-switch units  162  and  163  comprises a balun that is used to convert electrical signals that are balanced with respect to ground (differential) into signals that are unbalanced (single-ended) and vice versa. The balun unit  161  is connected as an input/output (I/O) port (port 1) of the wireless communications chipset  100 . The balun-switch units  162  and  163  serve as another I/O ports (ports 2 and 3) of the wireless communications chipset  100 . The switching device  20  and the connection device  30  may be integrated as a path selection circuit and disposed on a printed circuit board (PCB). 
         [0032]    The WiFi module  120  is connected with the BT module  130  for communicating operation statuses and power control information to each other, so that the transmission power of either the WiFi module  120  or the BT module  130  may be adjusted to reduce the signal interference to the other of the WiFi module  120  and the BT module  130 . The WiFi Tx front-end  151  is connected to the WiFi module  120  and performs the front-end functions for transmission, such as modulation of the transmitting carrier signals. The WiFi/BT Rx front-end  152  is connected to the separator  140  and performs the front-end functions for reception, such as demodulation of the received carrier signals. The separator  140  is configured to separate the WiFi and BT Rx signals in the combined signals from the WiFi/BT Rx front-end  152 , and to direct the separated WiFi and BT Rx signals to the WiFi module  120  and the BT module  130 , respectively. Similarly, both of the BT Tx front-ends  153  and  155  are connected to the BT module  130  and perform the front-end functions for transmission, and the BT Rx front-end  154  is connected to the BT module  130  and performs the front-end functions for reception. The operation states of the WiFi Tx front-end  151 , the WiFi/BT Rx front-end  152 , the BT Tx front-end  153 , the BT Rx front-end  154 , and the BT Tx front-end  155  are controlled by the control unit  110 . By setting the operation state to “ON”, the corresponding front-end unit will be activated. On the contrary, by setting the operation state to “OFF”, the corresponding front-end unit will be deactivated. Or, alternatively, the operation state may be set to “DOWN” so that the corresponding front-end unit operates in an idle mode in which most of circuits are shut down and a low-rate clock is working to reduce power consumption. It is to be understood that, when any front-end unit is set to “OFF” or “DOWN”, the corresponding transmission or reception capability is loss. The control unit  110  may also operate as a packet traffic arbitrator (PTA) to receive the traffic requests from both of the WiFi module  120  and the BT module  130 , and to determine whether the WiFi traffic request has collided with the BT traffic request in a time period. If a collision has occurred, the control unit  110  may grant both of the traffic requests or may only grant one of the traffic requests while rejecting the other, depending on the frequency bands, priorities, operation types (e.g. Tx/Rx operation), power levels or others parameters of the traffic requests. Additionally, the control unit  110  further controls the switch device  20  to connect the terminal  22  to the terminal  24  or  26 , the balun-switch unit  162  to connect the terminal  162 - 2  to the terminal  162 - 4  or  162 - 6 , and the balun-switch unit  163  to connect the terminal  163 - 2  to the terminal  163 - 4  or  163 - 6 . Accordingly, by controlling the switch device  20 , the balun-switch unit  162 , and the balun-switch unit  163 , and controlling the operation states of the WiFi Tx front-end  151 , the WiFi/BT Rx front-end  152 , the BT Tx front-end  153 , the BT Rx front-end  154 , and the BT Tx front-end  155 , the control unit  110  determines the antenna path of the WiFi module  120  and the BT module  130 . It is to be understood that the control unit  110  may be integrated into the WiFi module  120  or the BT module  130  to reduce hardware costs. 
         [0033]    The switching device  20  may be implemented by a single-pole double-thrown (SPDT) switch, which consists of three terminals  22 ,  24  and  26  and is configured to selectively connect the terminal  22  to the terminal  24  and  26 , as shown in  FIG. 5A . In addition, the terminals  24  and  26  are connected to the ports 1 and 2 of the wireless communications chipset  100 , respectively. In other embodiments, the switching device  20  may also be implemented by a double-pole double-thrown (DPDT) as shown in  FIG. 5B . The terminal  24  is selectively connected to the terminals  22  or  28 , and the terminal  26  is selectively connected to the terminals  22  or  28 . The terminal  28  may be coupled or connected to an external node for impedance matching. 
         [0034]    The connection device  30  consists of three ports  32 ,  34  and  36  and is configured to couple the ports  32  and  34  to form a transceiving path (through path), and to couple the ports  32  and  36  to form another transceiving path (coupled path), wherein the port  34  is isolated from the port  36  by substantially 20 dB and the electrical signals passing through the path between ports  32  and  36  are substantially attenuated by 6 or 10 dB. Referring to  FIG. 6A , the connection device  30  may contain an attenuator attenuating electrical signals passing through the ports  32  and  36  by 20 dB. Alternatively, the connection device  30  may contain a directional coupler, as shown in  FIG. 6B , in which the ports  32  and  34  are coupled as a through path, the port  36  and an external node  38  are connected as a through path, the ports  32  and  36  are coupled as a coupled path, and the ports  34  and  36  are isolated with a loss around 20-40 dB. The through path is direct or indirect through and the external node  38  may be a resistor (for example, a 50Ω resistor or a 50Ω equivalent termination). It is noted that the through path between the ports  32  and  34  may have a loss of 0.5 dB substantially while the coupled path between ports  32  and  36  may have a loss of 10 dB substantially, or the through path between ports  32  and  34  may have a loss of 1.2 dB substantially while the coupled path between ports  32  and  36  may have a loss of 6 dB substantially. 
         [0035]      FIG. 7A  and  FIG. 7B  illustrate two embodiments of the directional coupler shown in  FIG. 6B . Referring to  FIG. 7A , two transmission lines are set sufficiently close together, such that electrical signals (or energy) directed from the port  32  (connected to a port called an input port) to the port  34  (connected to a port called a transmitted port) is coupled to the port  36  (connected to a port called a coupled port). Similarly, referring to  FIG. 7B , electrical signals (or energy) directed from the ports  36  (connected to a port called an input port) to a transmitted port (such as port  38  in  FIG. 6B ) is coupled to the port  32  (connected to a port called a coupled port) and isolated from the port  34  (connected to a port called an isolated port), such that the coupled signals can be added to electrical signals passing between the ports  32  and  34 . 
         [0036]    In addition to the attenuator ( FIG. 6A ) and the directional coupler ( FIG. 6B ), the connection device  30  may be implemented in a power divider, in which the ports  34  and  36  are isolated and both have a loss of 3 dB ideally (3.5 dB in practice). Furthermore, the connection device  30  may be implemented in a power splitter. The structure of the power splitter is similar to the power divider, but with different losses between the output ports. For a power splitter, the losses of the ports  34  and  36  are different. For example, the port  36  may have a loss of 10 dB while the port  34  may have a loss of 0.5 dB, or the port  36  may have a loss of 6 dB while the port  34  may have a loss of 1 dB. In addition, the connection device  30  may be implemented by a PCB pad with an input port and two output ports, in which one of the output ports has a loss of NdB and another output port has a loss of smaller than 1 dB, as designed based on requirement. It is noted that the power splitter may be implemented using a directional coupler, such as the one shown in  FIG. 6B , with the port  38  connected to a resistor for impedance matching and ports  34  and  36  being isolated. With the power splitter implemented using a directional coupler as shown in  FIG. 6B , the port  36  may have a loss of 10 dB while the port  34  may have a loss of 0.5 dB, or the port  36  may have a loss of 6 dB while the port  34  may have a loss of 1 dB. 
         [0037]      FIGS. 8A to 8C  show a flowchart of the method for reducing interference between the WiFi module  120  and the BT module  130  in accordance with an embodiment of the invention. Although the flow is explained with reference to the system  400  as shown in  FIG. 4 , the present invention is not limited thereto. Other antenna structures or tranceiver configurations capable of conducting co-existence of two or more communications modules can be applied as well. To begin, the WiFi module  120  determines the frequency band for transmitting and receiving WiFi signals when connected to an AP (step S 801 ). The WiFi module  120  may determine the frequency band when connected to the AP with reference to a channel table. In some conditions, such as WiFi module  120  is configured to comply with 802.11n specification, the WiFi module  120  determines the frequency band with a primary channel and a secondary channel. When the frequency band is determined, the WiFi module  120  calculates the in-band ranges for the BT Rx signals and the WiFi Rx signals (step S 802 ), wherein the in-band ranges for the BT Rx signals and the WiFi Rx signals indicate the frequency ranges where the BT Rx signals and the WiFi Rx signals may have in-band interference caused by the WiFi Tx signals and the BT Tx signals, respectively, as will be further illustrated in  FIGS. 9A and 9B . In one embodiment, the in-band interference may be caused when both of the WiFi signals and the BT signals are transmitted or received in the same frequency; while in other embodiments, the in-band interference may be caused when the WiFi signals and the BT signals are transmitted or received in nearby frequencies. By calculating the in-band ranges for the BT Rx signals and the WiFi Rx signals, the WiFi module  120  may generate two channel bitmaps which indicate the in-band ranges for the BT Rx signals, wherein one channel bitmap indicates which channels carrying BT Rx signals may have in-band interference caused by the WiFi Tx signals in the primary channel, and the other channel bitmap indicates which channels carrying BT Rx signals may have in-band interference caused by the WiFi Tx signals in the secondary channel. Likewise, the WiFi module  120  may generate two channel bitmaps which indicate the in-band ranges for the WiFi Rx signals, wherein one channel bitmap indicates which channels carrying BT Tx signals may cause in-band interference to the WiFi Rx signals in the primary channel, and the other channel bitmap indicates which channels carrying BT Tx signals may cause in-band interference to the WiFi Rx signals in the secondary channel. Subsequently, the WiFi module  120  sends the in-band ranges for the WiFi Rx signals and the BT Rx signals to the BT module  130  (step S 803 ). When the in-band ranges for the WiFi Rx signals and the BT Rx signals from the WiFi module  120  are received, it is determined whether an Rx operation or a Tx operation is going to be performed by the BT module  130  in a forthcoming time period (step S 804 ). If the BT module  130  occupies the time period for an Rx operation, the BT module  130  determines whether in-band interference may be caused to the BT Rx signals by potential WiFi Tx signals in the time period according to the in-band range for the BT Rx signals and the traffic pattern of the BT Rx signals (step S 805 ). In one embodiment, the BT module  130  may determine whether there may be in-band interference by checking if any one of the next N hopped channels used by the BT Rx signals is in the in-band range for the BT Rx signals. That is, if one of the next N hopped channels used by the BT Rx signals is in the frequency band or near the frequency band of the WiFi Tx signals, then in-band interference may be caused to the BT Rx signals by potential WiFi Tx signals. After determining whether in-band interference may be caused, the BT module  130  sends to the WiFi module  120 , the determination result, and the signal indicators of the BT Rx signals (step S 806 ). In one embodiment, the BT module  130  may also send the traffic pattern information of the BT Rx signals to the WiFi module  120 , including the starting time, duration, and repeating interval of the BT Rx signals. When the determination result is received, it is determined whether a Tx operation is going to be performed by the WiFi module  120  in the time period (step S 807 ). If so, the WiFi module  120  adjusts the transmission power of the WiFi Tx signals according to the determination result and the signal indicators of the BT Rx signals and the WiFi Tx signals. To be more specific, it is first determined whether the determination result indicates that in-band interference may be caused (step S 808 ). If the determination result indicates to the WiFi module  120  that the WiFi Tx signals may cause in-band interference to the BT Rx signals, the WiFi module  120  decreases the transmission power of the WiFi Tx signals according to the signal indicators of the BT Rx signals and the WiFi Tx signals, so that the BT Rx signals may be successfully received (step S 809 ). Additionally, the WiFi module  120  may further determine when to decreases the transmission power of the WiFi Tx signals according to the traffic pattern information of the BT Rx signals. Otherwise, if the determination result indicates to the WiFi module  120  that the WiFi Tx signals do not cause in-band interference to the BT Rx signals, the WiFi module  120  may use normal power to transmit the WiFi Tx signals (step S 810 ). Subsequent to step S 807 , if not, the process goes back to wait for the next upcoming traffic requests from the WiFi module  120  and the BT module  130 . The signal indicators of the BT Rx signals and the WiFi Tx signals may include received signal strength indication (RSSI), signal to noise ratio (SNR), adjacent channel interference (ACI), packet error rate (PER), or bit error rate (BER) of the BT Rx signals and the WiFi Tx signals, respectively. In other embodiments, the transmission power of the WiFi Tx signals may also be adjusted according to the frequency offset between the frequencies or channels used by the BT Rx signals and the WiFi Tx signals, or the transceiving modulation types of the BT Rx signals and the WiFi Tx signals. 
         [0038]      FIG. 9A  is a diagram illustrating exemplary power control of the WiFi Tx signals to reduce in-band interference to the BT Rx signals in accordance with an embodiment of the invention. As shown in  FIG. 9A , the WiFi Tx signals are transmitted within the frequency range f1, and the BT Rx signals are received in a hopping frequency sequence. The adjustment of the transmission power for the WiFi Tx signals is determined according to the frequency offset between the WiFi Tx signals and the BT Rx signals. The in-band range for BT Rx signals (depicted as f1′) indicates a frequency range in which in-band interference may be occurred to the BT Rx signals received with the hopped frequency being in the frequency range. The in-band range f1′ may be determined according to the operational frequency ranges and the anti-interference ability of the WiFi module  120  and the BT module  130 . As shown in  FIG. 9A , when the hopped frequency of the BT Rx signals is not within the in-band range f1′ (depicted with solid arrows as shown in  FIG. 9A ) or the frequency offset between the hopped frequency of the BT Rx signals and the frequency range f1 of the WiFi Tx signals is greater than d1, the WiFi module  120  may use normal transmission power P1 to transmit the WiFi Tx signals without causing in-band interference to the BT Rx signals. When the hopped frequency of the BT Rx signals is within the in-band range f1′ (depicted with dashed arrows as shown in  FIG. 9A ) or the frequency offset between the hopped frequency of the BT Rx signals and the frequency range f1 of the WiFi Tx signals is less than or equal to d1, the WiFi module  120  may decrease the transmission power from P1 to P2 to reduce the in-band interference to the BT Rx signals. In addition, though not shown, the WiFi module  120  may further decrease the transmission power to further reduce the in-band interference to the BT Rx signals when the hopped frequency of the BT Rx signals is in f1. In addition to the frequency offset, the adjustment of the transmission power for the WiFi Tx signals may be determined according to the transmitting or receiving modulation type(s) of the WiFi Tx signals and/or the BT Rx signals. It is noted that the transmission power of the WiFi Tx signal is decreased in a way that the in-band interference to the BT Rx signals is reduced to satisfy a minimum requirement for the BT Rx signals to be successfully received by the BT module  130 . For example, as shown in  FIG. 10A , the region R1 represents the situation where both of the signal qualities of the WiFi and BT signals are good, i.e. both of the RSSIs of the WiFi and BT signals are greater than a threshold value, and the region R2 represents the situation where both of the signal qualities of the WiFi and BT signals are bad, i.e. both of the RSSIs of the WiFi and BT signals are less than the threshold value. In the region R1, the line L1 represents the WiFi Tx power corresponding to the RSSIs of the WiFi and BT signals, where the WiFi Tx power may be increased as the RSSI of the BT Rx signals increases and decreased as the RSSI of the BT signals decreases. The slope of the line L1 may be determined according to anti-interference ability of the WiFi module  120  and the BT module  130 . In the region R2, since both of the signal qualities of the WiFi and BT signals are bad, adjusting the power of the WiFi Tx signals may not help to maintain the successful reception of the BT Rx signals, so arbitration between the traffics of the WiFi module  120  and the BT module  130  may be employed. Since arbitration is employed to make sure only one module is active for the time period, the WiFi module  120  may use the original transmission power for the WiFi Tx signals, as depicted with the line L1′. In another embodiment, the transmission power for the WiFi Tx signals may be adjusted in a hierarchical fashion. For the RSSIs of the WiFi and BT signals in a first predetermined range, the transmission power for the WiFi Tx signals may be adjusted to a first level, and for the RSSIs of the WiFi and BT signals in a second predetermined range, the transmission power for the WiFi Tx signals may be adjusted to a second level, and so on. Although the embodiments described above use the RSSIs as signal indicators for the WiFi and BT signals, other signal indicators, such as signal to noise ratios (SNR), adjacent channel interferences (ACI), packet error rates (PER), and bit error rates (BER), may be employed for determining the adjustment of the transmission power of the WiFi module  120 . 
         [0039]    Subsequent to step S 804 , if the BT module  130  occupies the time period for a Tx operation, the BT module  130  prepares and sends the traffic parameters of the BT Tx signals to the WiFi module  120  (step S 811 ). The traffic parameters of the BT Tx signals may include information concerning when the BT Tx signals will be transmitted, and what power level, modulation type, and channel will be used for transmitting the BT Tx signals. When the traffic parameters of the BT Tx signals are received from the BT module  130 , it is determined whether an Rx operation is going to be performed by the WiFi module  120  in the time period (step S 812 ). If so, the BT module  130  determines whether the BT Tx signals may cause in-band interference to the WiFi Rx signals in the time period according to the in-band range for the WiFi Rx signals and the traffic parameters of the WiFi Rx signals (step S 813 ). If so, the BT module  130  decreases the transmission power of the BT Tx signals according to the signal indicators of the WiFi Rx signals and the BT Tx signals, so that the WiFi Rx signals may be successfully received (step S 814 ). Otherwise, if the BT Tx signals do not cause in-band ranges to the WiFi Rx signals in the time period, then normal transmission power of the BT Tx signals may be used (step S 815 ). Subsequent to step S 812 , if not, the process goes back to wait for the next upcoming traffic requests from the WiFi module  120  and the BT module  130 . The signal indicators of the BT Tx signals and the WiFi Rx signals may include received signal strength indication (RSSI), signal to noise ratio (SNR), adjacent channel interference (ACI), packet error rate (PER), or bit error rate (BER) of the BT Tx signals and the WiFi Rx signals, respectively. In other embodiments, the transmission power of the BT Tx signals may also be adjusted according to the frequency offset between the frequencies or channels used by the WiFi Rx signals and the BT Tx signals, or the transceiving modulation types of the WiFi Rx signals and the BT Tx signals. 
         [0040]      FIG. 9B  is a diagram illustrating exemplary power control of the BT Tx signals to reduce in-band interference to the WiFi Rx signals in accordance with an embodiment of the invention. As shown in  FIG. 9B , the WiFi Rx signals are received in the frequency range f2, and the BT Tx signals are transmitted in a hopping frequency sequence. The in-band range for the WiFi Rx signals (depicted as f2′) indicates a frequency range in which in-band interference may be occurred to the WiFi Rx signals when the BT Tx signals are transmitted with the hopped frequency being in the frequency range. The in-band range f2′ may be determined according to the operational frequency ranges and the anti-interference ability of the WiFi module  120  and the BT module  130 . As shown in  FIG. 9B , when the hopped frequency of the BT Tx signals is not within the in-band range f2′ (depicted with solid arrows as shown in  FIG. 9B ) or the frequency offset between the hopped frequency of the BT Tx signals and the frequency range f2 of the WiFi Rx signals is greater than d2, the BT module  130  may use normal transmission power P3 to transmit the BT Tx signals without causing in-band interference to the WiFi Rx signals. When the hopped frequency of the BT Tx signals is within the in-band range f2′ (depicted with dashed arrows as shown in  FIG. 9B ) or the frequency offset between the hopped frequency of the BT Tx signals and the frequency range f2 of the WiFi Rx signals is less than or equal to d2, the BT module  130  may decrease the transmission power from P3 to P4 to reduce the in-band interference to the WiFi Rx signals. In addition, though not shown, the BT module  130  may further decrease the transmission power to further reduce the in-band interference to the WiFi Rx signals when the hopped frequency of the BT Tx signals is in f2. In addition to the frequency offset, the adjustment of the transmission power for the BT Tx signals may be determined according to the transmitting or receiving modulation type(s) of the BT Tx signals and/or the WiFi Rx signals. It is noted that the transmission power of the BT Tx signal is decreased in a way that the in-band interference to the WiFi Rx signals is reduced to satisfy a minimum requirement for the WiFi Rx signals to be successfully received by the WiFi module  120 . For example, as shown in  FIG. 10B , the region R1 represents the situation where both of the signal qualities of the WiFi and BT signals are good, i.e. both of the RSSIs of the WiFi and BT signals are greater than a threshold value, and the region R2 represents the situation where both of the signal qualities of the WiFi and BT signals are bad, i.e. both of the RSSIs of the WiFi and BT signals are less than the threshold value. In the region R1, the line L2 represents the BT Tx power corresponding to the RSSIs of the WiFi and BT signals, where the BT Tx power may be decreased as the RSSI of the BT signals increases (i.e. high RSSI of the BT signals indicates that the distance to the peer communication device is short, so smaller transmission power may be used) and increased as the RSSI of the Rx signals decreases (i.e. low RSSI of the BT signals indicates that the distance to the peer communication device is long, so greater transmission power may be used). The slope of the line L2 may be determined according to the anti-interference ability of the WiFi module  120  and the BT module  130 . In the region R2, since both of the signal qualities of the WiFi and BT signals are bad, adjusting the power of the BT Tx signals may not help to maintain a successful reception of the WiFi Rx signals, so arbitration between the traffics of the WiFi module  120  and the BT module  130  may be employed. Since arbitration is employed to make sure only one module is active for the time period, the BT module  130  may use the original transmission power for the BT Tx signals, as depicted with the line L2′. In another embodiment, the transmission power for the BT Tx signals may be adjusted in a hierarchical fashion. For the RSSIs of the WiFi and BT signals in a first predetermined range, the transmission power for the BT Tx signals may be adjusted to a first level, and for the RSSIs of the WiFi and BT signals in a second predetermined range, the transmission power for the BT Tx signals may be adjusted to a second level, and so on. Although the embodiments described above use the RSSIs as signal indicators for the WiFi and BT signals, other signal indicators, such as SNR, ACI, PER, and BER, may be employed for determining the adjustment of the transmission power of the BT module  130 . 
         [0041]      FIGS. 11A to 11C  show a flowchart of the method for reducing interference between the WiFi module  120  and the BT module  130  in accordance with another embodiment of the invention. Similar to the steps S 801  to S 803  in  FIG. 8 , the method in this embodiment also begins with obtaining the in-band ranges for the BT Rx signals and the WiFi Rx signals by the WiFi module  120  and the BT module  130  (steps S 1101 ˜S 1103 ). The method in this embodiment subsequently determines whether to apply power control according to the traffic parameters and the signal indicators of both the WiFi module  120  and BT module  130  (step S 1104 ). If so, the process proceeds to step S 1105 . Otherwise, the process ends. In one embodiment, power control is applied when both of the RSSIs of the BT Rx signals and WiFi Rx signals are greater than a good-quality threshold value. That is, having the RSSIs greater than the good-quality threshold value means that the signal strength of the BT Rx signals and WiFi Rx signals is good enough to withstand some level of interference without jeopardizing the successful reception of the BT Rx signals and WiFi Rx signals. In another embodiment, power control may not be applied when the RSSI of the BT Rx signals or the WiFi Rx signals is lower than a fair-quality threshold value and the BT Rx signals or the WiFi Rx signals are for real-time applications. That is, having the RSSI of the BT Rx signals or the WiFi Rx signals lower than the fair-quality threshold value means that the signal strength of the BT Rx signals or the WiFi Rx signals is too weak to withstand any interference and even decreasing the transmission power of the transmitting module may still lead to an unsuccessful reception of the BT Rx signals or the WiFi Rx signals. Meanwhile, if the BT Rx signals or the WiFi Rx signals are for real-time applications, the data carried in the BT Rx signals or the WiFi Rx signals should be considered critical and the successful reception of the BT Rx signals or the WiFi Rx signals should be a first priority. Subsequent to S 1104 , if power control is to be applied, a series of inspections with respect to the operation statuses, the traffic parameters, and the signal indicators of the WiFi module  120  and BT module  130  are performed to determine whether in-band interference will be caused between the WiFi module  120  and BT module  130 . Specifically, it is determined whether an Rx operation or a Tx operation is going to be performed by the BT module  130  in a forthcoming time period (step S 1105 ). If the BT module  130  occupies the time period for an Rx operation, the BT module  130  determines whether in-band interference may be caused to the BT Rx signals by potential WiFi Tx signals in the time period according to the in-band range for the BT Rx signals and the traffic pattern of the BT Rx signals (step S 1106 ). In one embodiment, the BT module  130  may determine whether there may be in-band interference by checking if any one of the next N hopped channels used by the BT Rx signals is in the in-band range for the BT Rx signals. That is, if one of the next N hopped channels used by the BT Rx signals is in the frequency band or near the frequency band of the WiFi Tx signals, then in-band interference may be caused to the BT Rx signals by potential WiFi Tx signals. After determining whether in-band interference may be caused, the BT module  130  sends the determination result and the signal indicators of the BT Rx signals to the WiFi module  120  (step S 1107 ). In one embodiment, the BT module  130  may also send the traffic pattern information of the BT Rx signals to the WiFi module  120 , including the starting time, duration, and repeating interval of the BT Rx signals. When the determination result is received, it is determined whether a Tx operation is going to be performed by the WiFi module  120  in the time period (step S 1108 ). If so, the WiFi module  120  adjusts the transmission power of the WiFi Tx signals according to the determination result and the signal indicators of the BT Rx signals and the WiFi Tx signals. To be more specific, it is first determined whether the determination result indicates that in-band interference may be caused (step S 1109 ). If the determination result indicates to the WiFi module  120  that the WiFi Tx signals may cause in-band interference to the BT Rx signals, the WiFi module  120  decreases the transmission power of the WiFi Tx signals according to the signal indicators of the BT Rx signals and the WiFi Tx signals, so that the BT Rx signals may be successfully received (step S 1110 ). It is noted that the transmission power of the WiFi Tx signal is decreased in a way that the in-band interference to the BT Rx signals is reduced to satisfy the minimum requirement for the BT Rx signals to be successfully received by the BT module  130 . Otherwise, if the determination result indicates to the WiFi module  120  that the WiFi Tx signals do not cause in-band interference to the BT Rx signals, the WiFi module  120  may use normal power to transmit the WiFi Tx signals (step S 1111 ). Subsequent to step S 1108 , if not, the process goes back to wait for the next upcoming traffic requests from the WiFi module  120  and the BT module  130 . The signal indicators of the BT Rx signals and the WiFi Tx signals may include RSSI, SNR, ACI, PER, or BER of the BT Rx signals and the WiFi Tx signals, respectively. In other embodiments, the transmission power of the WiFi Tx signals may also be adjusted according to the frequency offset between the frequencies or channels used by the BT Rx signals and the WiFi Tx signals, or the transceiving modulation types of the BT Rx signals and the WiFi Tx signals. 
         [0042]    Subsequent to step S 1105 , if the BT module  130  occupies the time period for a Tx operation, the BT module  130  prepares and sends the traffic parameters of the BT Tx signals to the WiFi module  120  (step S 1112 ). The traffic parameters of the BT Tx signals may include information concerning when the BT Tx signals will be transmitted, and what power level, modulation type, and channel will be used for transmitting the BT Tx signals. When the traffic parameters of the BT Tx signals are received from the BT module  130 , it is determined whether an Rx operation is going to be performed by the WiFi module  120  in the time period (step S 1113 ). If so, the BT module  130  determines whether the BT Tx signals may cause in-band interference to the WiFi Rx signals in the time period according to the in-band range for the WiFi Rx signals and the traffic parameters of the WiFi Rx signals (step S 1114 ). If so, the BT module  130  decreases the transmission power of the BT Tx signals according to the signal indicators of the WiFi Rx signals and the BT Tx signals, so that the WiFi Rx signals may be successfully received (step S 1115 ). Otherwise, if the BT Tx signals do not cause in-band ranges to the WiFi Rx signals, then normal transmission power of the BT Tx signals may be used (step S 1116 ). Subsequent to step S 1113 , if not, the process goes back to wait for the next upcoming traffic requests from the WiFi module  120  and the BT module  130 . The signal indicators of the BT Tx signals and the WiFi Rx signals may include RSSI, SNR, ACI, PER, or BER of the BT Tx signals and the WiFi Rx signals, respectively. In other embodiments, the transmission power of the BT Tx signals may also be adjusted according to the frequency offset between the frequencies or channels used by the WiFi Rx signals and the BT Tx signals, or the transceiving modulation types of the WiFi Rx signals and the BT Tx signals. It is noted that the transmission power of the WiFi Tx signals or the BT Tx signals in step S 1109  or S 1114  is decreased in a way that the in-band interference to the BT Rx signals or the WiFi Rx signals is reduced to satisfy the minimum requirement for the BT Rx signals or the WiFi Rx signals to be successfully received by the BT module  130  or the WiFi module  120 , respectively. 
         [0043]    For the components and connection configurations therebetween in the wireless communications chipset  100  described above, it is noted that the WiFi module  120  has one Tx front-end and one Rx front-end, while the BT modules  130  has two Tx front-ends and two Rx front-ends. After the transmission power control is performed as described above, the operation types of the system  400  with respect to the Tx front-ends and Rx front-end of the WiFi module  120  and the BT module  130  are determined Table 1 below depicts a combination of potential operation types performed by the system  400  according to an embodiment of the invention: 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Operation Type 
                   
               
             
          
           
               
                 Mode 
                 WiFi_Tx 
                 WiFi_Rx 
                 BT_Tx 
                 BT_Rx 
               
               
                   
               
               
                 Mode 1 
                 0 
                 0 
                 1 (Port 2) 
                 0 
               
               
                 Mode 2 
                 0 
                 0 
                 0 
                 1 (Port 2) 
               
               
                 Mode 3 
                 1 (Port 1) 
                 0 
                 0 
                 0 
               
               
                 Mode 4 
                 0 
                 1 (Port 2) 
                 0 
                 0 
               
               
                 Mode 5 
                 0 
                 1 (Port 2) 
                 1 (Port 3) 
                 0 
               
               
                 Mode 6 
                 0 
                 1 (Port 2) 
                 0 
                 1 (Port 3) 
               
               
                 Mode 7 
                 1 (Port 1) 
                 0 
                 0 
                 1 (Port 3) 
               
               
                 Mode 8 
                 1 (Port 1) 
                 0 
                 1 (Port 3) 
                 0 
               
               
                 Mode 9 
                 0 
                 1 (Port 2) 
                 1 (Port 2) 
                 0 
               
               
                 Mode 10 
                 0 
                 1 (Port 2) 
                 0 
                 1 (Port 2) 
               
               
                 Mode 11 
                 1 (Port 1) 
                 0 
                 0 
                 1 (Port 2) 
               
               
                 Mode 12 
                 1 (Port 1) 
                 0 
                 1 (Port 2) 
                 0 
               
               
                   
               
             
          
         
       
     
         [0044]    In Table 1 above, “1” means TRUE, representing activation of a corresponding operation, whereas “0” means FALSE, representing deactivation of a corresponding operation. The operation modes in Table 1 above will be explained in more details with references to the flowchart in  FIG. 12  below. 
         [0045]      FIGS. 12A to 12G  show a flowchart of the coexistence between WiFi and BT modules handled by the control unit  110  in accordance with an embodiment of the invention. The procedure begins with obtaining information regarding potential operation(s) that is/are going to be performed by the WiFi module  120  and BT module  130  in a forthcoming time period (step S 1201 ). Next, a series of inspections with respect to the obtained information are accordingly performed to determine whether only one or both of the WiFi module  120  and BT module  130  occupy a time period, and whether the time period occupied for a Tx/Rx operation by one module collides with an Tx/Rx operation by the other module. Specifically, it is determined whether only the BT module  130  occupies the time period for a Tx operation (step S 1202 ). If so, the control unit  110  sends control signals to activate the BT Tx front-end  153 , switch the balun-switch unit  162  to the BT Tx front-end  153 , and switch the switching device  20  to the port 2 for the time period (mode 1) (step S 1203 ), thereby enabling the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  153 , the port 2, and the through path between the ports  34  and  32  in sequence to the antenna  10 . Subsequent to step S 1202 , if not, it is determined whether only the BT module  112  occupies the time period for an Rx operation (step S 1204 ). If so, the control unit  110  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , and switch the switching device  20  to the port 2 for the time period (mode 2) (step S 1205 ), thereby enabling the BT Rx signals to be received from the antenna  10  by the BT module  130  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. Subsequent to step S 1104 , if not, it is determined whether only the WiFi module  120  occupies the time period for a Tx operation (step S 1206 ). If so, the control unit  110  sends control signals to activate the WiFi Tx front-end  151  and switch the switching device  20  to the port 1 for the time period (mode 3) (step S 1207 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the port 1, and the through path between the ports  34  and  32  in sequence to the antenna  10 . Subsequent to step S 1206 , if not, it is determined whether only the WiFi module  120  occupies the time period for an Rx operation (step S 1208 ). If so, the control unit  110  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , and switch the switching device  20  to the port 2 for the time period (mode 4) (step S 1209 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. 
         [0046]    Subsequent to step S 1208 , if not, it means that both of the WiFi module  120  and the BT module  130  occupy the time period for their operations. However, it is noted that when a WiFi Rx/Tx operation and a BT Rx/Tx operation both take place at the same time, the WiFi Rx/Tx signals may interfere with the BT Rx/Tx signals, and vice versa. Consequently, the larger the wanted power of the WiFi Tx signals is, the greater the interferences are to the BT Rx/Tx signals, and vice versa. For this reason, it is determined whether transceiving statuses for the WiFi Rx/Tx signals and the BT Rx/Tx signals are in an operational range where coexistence is achievable (step S 1210 ). The transceiving status may be wanted power, RSSI, historical PER, historical BER, SNR, or interference-to-signal ratio (ISR) of the WiFi Rx/Tx signals or the BT Rx/Tx signals. In addition, the transceiving status may be a certain number of reconnections for historical WiFi Rx/Tx operations or the BT Rx/Tx operations. 
         [0047]    Note that for the cases in which the WiFi module  120  and the BT module  130  occupy the time period for Tx operation and Rx operation, respectively, or the WiFi module  120  and the BT module  130  occupy the time period for Rx operation and Tx operation, respectively, if the power control as described in  FIG. 8  has been performed due to potential in-band interference between the WiFi module  120  and the BT module  130 , then the adjusted power may ensure that the transceiving statuses for the WiFi Rx/Tx signals and the BT Rx/Tx signals are in an operational range where coexistence is achievable. 
         [0048]    Subsequent to step S 1210 , if so, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Rx and Tx operations, respectively (step S 1211 ). If so, the control unit  110  sends control signals to activate the WiFi/BT Rx front-end  152  and the BT Tx front-end  155 , switch the balun-switch units  162  and  163  to the WiFi/BT Rx front-end  152  and the BT Tx front-end  155 , respectively, and switch the switching device  20  to the port 2 for the time period (mode 5) (step S 1212 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence, along with the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  155 , the port 3, and the coupled path between the ports  32  and  36  in sequence to the antenna  10 . Subsequent to step S 1211 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Rx operations (step S 1213 ). If so, the control unit  110  sends control signals to activate the WiFi/BT Rx front-end  152  and the BT Rx front-end  154 , switch the balun-switch units  162  and  163  to the WiFi/BT Rx front-end  152  and the BT Rx front-end  154 , respectively, and switch the switching device  20  to the port 2 for the time period (mode 6) (step S 1214 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence, along with the BT Rx signals to be received from the antenna  10  by the BT module  130  via the coupled path between the ports  32  and  36 , the port 3, and the BT Rx front-end  154  in sequence. Subsequent to step S 1213 , if not, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Tx and Rx operations, respectively (step S 1215 ). If so, the control unit  110  sends control signals to activate the WiFi Tx front-end  151  and the BT Rx front-end  154 , switch the balun-switch unit  163  to the BT Rx front-end  154 , and switch the switching device  20  to the port 1 for the time period (mode 7) (step S 1216 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the balun unit  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 , along with the BT Rx signals to be received from the antenna  10  by the BT module  130  via the coupled path between the ports  32  and  36 , the port 3, and the BT Rx front-end  154  in sequence. Subsequent to step S 1215 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Tx operations (step S 1217 ). If so, the control unit  110  sends control signals to activate the WiFi Tx front-end  151  and the BT Tx front-end  155 , switch the balun-switch unit  163  to the BT Tx front-end  155 , and switch the switching device  20  to the port 1 for the time period (mode 8) (step S 1218 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the balun unit  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 , along with the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  155 , the port 3, and the coupled path between the ports  32  and  36  in sequence to the antenna  10 . 
         [0049]    Subsequent to step S 1210 , if not, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Rx and Tx operations, respectively (step S 1219 ). If so, the control unit  110  determines whether a collision has occurred in the traffic requests from the WiFi module  120  and the BT module  130 , and arbitrates which traffic request is to be granted when a collision has occurred (step S 1220 ). If the granted traffic request is from the WiFi module  120 , the control unit  110  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , and switch the switching device  20  to the port 2 for the time period (mode 9) (step S 1221 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. If the granted traffic request is from the BT module  130 , the control unit  110  sends control signals to activate the BT Tx front-end  153 , switch the balun-switch unit  162  to the BT Tx front-end  153 , and switch the switching device  20  to the port 2 for the time period (mode 9) (step S 1222 ), thereby enabling the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  153 , the balun-switch unit  162 , the port 2, and the through path between the ports  32  and  34  in sequence to the antenna  10 . Subsequent to step S 1219 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Rx operations (step S 1223 ). If so, the control unit sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , and switch the switching device  20  to the port 2 for the time period (mode 10) (step S 1224 ), thereby enabling a combined signal to be received from the antenna  10  by the separator  140  via the through path between ports  32  and  34 , the port 2, and the WiFi/BT Rx front-end  152  in sequence. Thereafter, the separator  140  separates them into the WiFi and BT Rx signals and further forwarded to the WiFi module  120  and BT module  130 , respectively. Subsequent to step S 1223 , if not, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Tx and Rx operations, respectively (step S 1225 ). If so, the control unit  110  determines whether a collision has occurred in the traffic requests from the WiFi module  120  and the BT module  130 , and arbitrates which traffic request is to be granted when a collision has occurred (step S 1226 ). If the granted traffic request is from the WiFi module  120 , the control unit  110  sends control signals to activate the WiFi Tx front-end  151  and switch the switching device  20  to the port 1 for the time period (mode 11) (step S 1227 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the balun unit  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 . If the granted traffic request is from the BT module  130 , the control unit  110  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , and switch the switching device  20  to the port 2 for the time period (mode 11) (step S 1228 ), thereby enabling the BT Rx signals to be received from the antenna  10  by the BT module  130  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. Subsequent to step S 1225 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Tx operations (step S 1229 ). If so, the control unit  110  determines whether a collision has occurred in the traffic requests from the WiFi module  120  and the BT module  130 , and arbitrates which traffic request is to be granted when a collision has occurred (step S 1230 ). If the granted traffic request is from the WiFi module  120 , the control unit  110  sends control signals to activate the WiFi Tx front-end  151  and switch the switching device  20  to the port 1 (mode 12) (step S 1231 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the balun unit  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 . If the granted traffic request is from the BT module  130 , the control unit  110  sends control signals to activate the BT Tx front-end  153 , switch the balun-switch unit  162  to the BT Tx front-end  153 , and switch the switching device  20  to the port 2 for the time period (mode 12) (step S 1232 ), thereby enabling the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  153 , the port 2, and the through path between the ports  32  and  34  in sequence to the antenna  10 . 
         [0050]    Those skilled in the art may readily modify the hardware structure of the system  400  by implementing the connection device  30  in a 3-port power splitter having an input port  32  and two output ports  34  and  36 . The first path between the input port  32  and the output port  34  has a first path loss, and the second path between the input port  32  and the output port  36  has a second path loss. For a power splitter with equal loss, the path loss of the first and second paths is the same, while it is different for an unequal-loss power splitter. For the coupling values for the power splitter, reference may be made to Table 2 below: 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Coupling Value 
                 Power 
               
               
                   
                 For Through Path 
                 Ratio (%) 
               
               
                   
                   
               
             
             
               
                   
                  3 dB 
                 50/50 
               
               
                   
                  6 dB 
                 75/25 
               
               
                   
                  8 dB 
                 85/15 
               
               
                   
                 10 dB 
                 90/10 
               
               
                   
                 15 dB 
                 97/3  
               
               
                   
                 20 dB 
                 99/1  
               
               
                   
                   
               
             
          
         
       
     
         [0051]    Taking the coupling value of 3 dB (3 dB directional coupler) for example, the through path has a path loss of 3 dB substantially, whereas the coupled path also has a path loss of 3 dB substantially. For the 6 dB directional coupler, the through path has a path loss of 1 dB substantially, whereas the coupled path also has a path loss of 6 dB substantially. For the 10 dB directional coupler, the through path has a path loss of 0.5 dB substantially, whereas the coupled path also has a path loss of 10 dB substantially. 
         [0052]    In another embodiment of the invention, an additional switch device may be included in the system  400 , as shown in  FIG. 13 . Similar to the system  400  in  FIG. 4 , the system  1300  herein also comprises the antenna  10  and the wireless communications chipset  100 . Regarding descriptions of the antenna  10  and the elements in the wireless communications chipset  100  excluding the control unit  110 , reference may be made to  FIG. 4 . However, the elements between the antenna  10  and the wireless communications chipset  100  in the system  1300  are different from those in the system  400 . A switching device  1320 , similar to the switching device  20 , is configured to selectively connect the terminal  22  to the terminal  24  and  26  as controlled by the control unit  1310 , wherein the terminal  24  is connected to the port 1, the terminal  26  is connected to the port 2, and the terminal  22  is connected to the port  34  of a connection device  1330 . The switching device  1320  may be implemented by an SPDT switch. The connection device  1330  is similar to the connection device  30 , in which the ports  32  and  34  are connected via a first through path, the ports  36  and  38  are connected via a second through path, the ports  32  and  36  are coupled via a first coupled path, the ports  34  and  38  are coupled via a second coupled path, the ports  34  and  36  are isolated, and the ports  32  and  38  are isolated, wherein the first and second through paths are direct or indirect through. In addition, the ports  32  and  38  are connected to the terminals  44  and  46  of a switching device  1340 , respectively, and the port  36  is connected to the port 3. The switching device  1340  is similar to the switching device  1320 , which consists of three terminals  42 ,  44 , and  46 , and is configured to selectively connect the terminal  42  to the terminal  44  and  46  as controlled by the control unit  1310 , wherein the terminal  42  is connected to the antenna  10 . The switching devices  1320  and  1340 , and the connection device  1330  may be integrated as a path selection circuit and disposed on a PCB. Note the first and second through paths may have a loss of 0.5 dB substantially, whereas the first and second coupled paths may have a loss of 10 dB substantially, or the first and second through paths may have a loss of 1 dB substantially, whereas the first and second coupled paths may have a loss of 6 dB substantially. 
         [0053]    In the following discussion, reference may be made to Table 1 and related descriptions. In response to the modification of the path selection circuit, the control unit  1310  performs similar but different function than that of  FIG. 4 .  FIGS. 14A to 14G  show a flowchart of the coexistence between WiFi and BT modules handled by the control unit  1310  in accordance with an embodiment of the invention. The procedure begins with obtaining information regarding potential operation(s) that is/are going to be performed by the WiFi module  120  and BT module  130  in a forthcoming time period (step S 1401 ). Next, a series of inspections with respect to the obtained information are accordingly performed to determine whether only one or both of the WiFi module  120  and BT module  130  occupy the time period, and whether the time period is occupied for a Tx/Rx operation by one module collides with an Tx/Rx operation by the other module. Specifically, it is determined whether only the BT module  130  occupies the time period for a Tx operation (step S 1402 ). If so, the control unit  1310  sends control signals to activate the BT Tx front-end  153 , switch the balun-switch unit  162  to the BT Tx front-end  153 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 1) (step S 1403 ), thereby enabling the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  153 , the port 2, and the through path between the ports  34  and  32  in sequence to the antenna  10 . Subsequent to step S 1402 , if not, it is determined whether only the BT module  130  occupies the time period for an Rx operation (step S 1404 ). If so, the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 2) (step S 1405 ), thereby enabling the BT Rx signals to be received from the antenna  10  by the BT module  130  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. Subsequent to step S 1404 , if not, it is determined whether only the WiFi module  120  occupies the time period for a Tx operation (step S 1406 ). If so, the control unit  1310  sends control signals to activate the WiFi Tx front-end  151 , switch the switching device  1320  to the port 1, and switch the switching device  1340  to the port  32  for the time period (mode 3) (step S 1407 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the port 1, and the through path between the ports  34  and  32  in sequence to the antenna  10 . Subsequent to step S 1406 , if not, it is determined whether only the WiFi module  120  occupies the time period for an Rx operation (step S 1408 ). If so, the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 4) (step S 1409 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. 
         [0054]    Subsequent to step S 1408 , if not, it means that both of the WiFi module  120  and the BT module  130  occupy the time period for their operations. Since the WiFi Rx/Tx signals may interfere with the BT Rx/Tx signals, and vice versa, it is determined whether the transceiving statuses for the WiFi Rx/Tx signals and the BT Rx/Tx signals are in an operational range where coexistence is achievable (step S 1410 ). The transceiveing status may be the wanted power, RSSI, historical PER, historical BER, SNR, or ISR of the WiFi Rx/Tx signals or the BT Rx/Tx signals. In addition, the transceiveing status may be a certain number of reconnections for historical WiFi Rx/Tx operations or the BT Rx/Tx operations. Subsequent to step S 1410 , if so, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Rx and Tx operations, respectively (step S 1411 ). If so, the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152  and the BT Tx front-end  155 , switch the balun-switch units  162  and  163  to the WiFi/BT Rx front-end  152  and the BT Tx front-end  155 , respectively, switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  or  38  for the time period (mode 5) (step S 1412 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence, along with the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  155 , the port 3, and the through path between the ports  36  and  38  in sequence to the antenna  10 . Subsequent to step S 1411 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Rx operations (step S 1413 ). If so, the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152  and the BT Rx front-end  154 , switch the balun-switch units  162  and  163  to the WiFi/BT Rx front-end  152  and the BT Rx front-end  154 , respectively, switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  or  38  for the time period (mode 6) (step S 1414 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence, along with the BT Rx signals to be received from the antenna  10  by the BT module  130  via the through path between the ports  36  and  38 , the port 3, and the BT Rx front-end  154  in sequence. Subsequent to step S 1413 , if not, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Tx and Rx operations, respectively (step S 1415 ). If so, the control unit  1310  sends control signals to activate the WiFi Tx front-end  151  and the BT Rx front-end  154 , switch the balun-switch unit  163  to the BT Rx front-end  154 , switch the switching device  1320  to the port 1, and switch the switching device  1340  to the port  32  or  38  for the time period (mode 7) (step S 1416 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 , along with the BT Rx signals to be received from the antenna  10  by the BT module  130  via the through path between the ports  36  and  38 , the port 3, and the BT Rx front-end  154  in sequence. Subsequent to step S 1415 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Tx operations (step S 1417 ). If so, the control unit  1310  sends control signals to activate the WiFi Tx front-end  151  and the BT Tx front-end  155 , switch the balun-switch unit  163  to the BT Tx front-end  155 , switch the switching device  1320  to the port 1, and switch the switching device  1340  to the port  32  or  38  for the time period (mode 8) (step S 1418 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , balun  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 , along with the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  155 , the port 3, and the through path between the ports  36  and  38  in sequence to the antenna  10 . 
         [0055]    Subsequent to step S 1410 , if not, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Rx and Tx operations, respectively (step S 1419 ). If so, the control unit  1310  determines whether a collision has occurred in the traffic requests from the WiFi module  120  and the BT module  130 , and arbitrates which traffic request is to be granted when a collision has occurred (step S 1420 ). If the granted traffic request is from the WiFi module  120 , the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 9) (step S 1421 ), thereby enabling the WiFi Rx signals to be received from the antenna  10  by the WiFi module  120  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. If the granted traffic request is from the BT module  130 , the control unit  1310  sends control signals to activate the BT Tx front-end  153 , switch the balun-switch unit  162  to the BT Tx front-end  153 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 9) (step S 1422 ), thereby enabling the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  153 , the port 2, and the through path between the ports  32  and  34  in sequence to the antenna  10 . Subsequent to step S 1419 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Rx operations (step S 1423 ). If so, the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 10) (step S 1424 ), thereby enabling a combined signal to be received from the antenna  10  by the separator  140  via the through path between ports  32  and  34 , the port 2, and the WiFi/BT Rx front-end  152  in sequence. Thereafter, the separator  140  separates them into the WiFi and BT Rx signals and further forwarded to the WiFi module  120  and BT module  130 , respectively. Subsequent to step S 1423 , if not, it is determined whether the WiFi module  120  and the BT module  130  occupy the time period for Tx and Rx operations, respectively (step S 1425 ). If so, the control unit  1310  determines whether a collision has occurred in the traffic requests from the WiFi module  120  and the BT module  130 , and arbitrates which traffic request is to be granted when a collision has occurred (step S 1426 ). If the granted traffic request is from the WiFi module  120 , the control unit  1310  sends control signals to activate the WiFi Tx front-end  151 , switch the switching device  1320  to the port 1, and switch the switching device  1340  to the port  32  for the time period (mode 11) (step S 1427 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , balun  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 . If the granted traffic request is from the BT module  130 , the control unit  1310  sends control signals to activate the WiFi/BT Rx front-end  152 , switch the balun-switch unit  162  to the WiFi/BT Rx front-end  152 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 11) (step S 1428 ), thereby enabling the BT Rx signals to be received from the antenna  10  by the BT module  130  via the through path between the ports  32  and  34 , the port 2, the WiFi/BT Rx front-end  152 , and the separator  140  in sequence. Subsequent to step S 1425 , if not, it is determined whether both of the WiFi module  120  and the BT module  130  occupy the time period for Tx operations (step S 1429 ). If so, the control unit  1310  determines whether a collision has occurred in the traffic requests from the WiFi module  120  and the BT module  130 , and arbitrates which traffic request is to be granted when a collision has occurred (step S 1430 ). If the granted traffic request is from the WiFi module  120 , the control unit  1310  sends control signals to activate the WiFi Tx front-end  151 , switch the switching device  1320  to the port 1, and switch the switching device  1340  to the port  32  for the time period (mode 12) (step S 1431 ), thereby enabling the WiFi Tx signals to be transmitted from the WiFi module  120  via the WiFi Tx front-end  151 , balun  161 , the port 1, and the through path between the ports  32  and  34  in sequence to the antenna  10 . If the granted traffic request is from the BT module  130 , the control unit  1310  sends control signals to activate the BT Tx front-end  153 , switch the balun-switch unit  162  to the BT Tx front-end  153 , switch the switching device  1320  to the port 2, and switch the switching device  1340  to the port  32  for the time period (mode 12) (step S 1432 ), thereby enabling the BT Tx signals to be transmitted from the BT module  130  via the BT Tx front-end  153 , the port 2, and the through path between the ports  32  and  34  in sequence to the antenna  10 . 
         [0056]    Without departing from the spirit of the invention, other embodiments of a method for the coexistence between the Bluetooth module and the WiMAX/LTE module, or between WiFi module and WiMAX/LTE module, handled by the control unit can be devised with relevant modifications according to the architectures in  FIGS. 4 and 13 , and the control flows in  FIGS. 12A to 12G  and  14 A to  14 G. 
         [0057]    Although the WiFi and BT wireless communication services are used for illustration of the invention, other wireless communication services can be used, such as Global Positioning System (GPS).  FIG. 15  shows another embodiment of a system for the coexistence between a Global Positioning System (GPS) and a subsystem sharing a single antenna, wherein the subsystem may be any one of the systems  400  and  1300  excluding the antenna  10 . The system  1500  comprises an antenna  10 , a diplexer  1510 , a GPS module  1520 , and a subsystem  1530 . The diplexer  1510 , which consists of three terminals  12 ,  14 , and  16 , is configured to connect the terminal  12  to both terminals  14  and  16  such that the GPS signals (Tx or Rx signal) are transmitted to/received from the shared antenna  10  via the diplexer  1510 , and the wireless signals of the subsystem  1530  (Tx or Rx signal) are simultaneously transmitted to/received from the shared antenna  10  via the diplexer  1510 . 
         [0058]    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.