Systems and methods for coexistence of a plurality of wireless communications modules

A wireless communications system is provided with a first wireless communications module, a second wireless communications module, and an RF module. The first wireless communications module transmits or receives a first wireless signal, and the second wireless communications module transmits or receives a second wireless signal. The RF module allocates a first transceiving path and a second transceiving path to the first wireless communications module and the second wireless communications module, respectively, to enable the transmission or reception of the first wireless signal and the second wireless signal at the same time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the coexistence of a plurality of wireless communications modules, and more particularly, to systems and methods for the coexistence schemes for a plurality of co-located wireless communications modules in a wireless communications device.

2. Description of the Related Art

To an increasing extent, a multitude of communication functions are being merged into mobile devices. As shown inFIG. 1, a cellular phone may connect to a wireless local area network (WLAN) via a WLAN 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 coexistence interference from BT systems. Referring toFIG. 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. BT 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 voice over internet protocol (VoIP) data via the WiFi module and further transmit the VoIP data through an established PAN to the BT handset, and vice versa. Alternatively, the cellular phone may transmit digital music through the established PAN to be played back in the BT handset. The WLAN and BT 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 WLAN and BT modules sharing a single antenna instead of multiple antennas.

As an example shows inFIG. 2, a BT system uses a Frequency Hopping Spread Spectrum (FHSS) and hops between 79 different 1 MHz-wide channels in a Bluetooth spectrum. A WLAN system carrier remains centered on one channel, which is overlapped with Bluetooth spectrum. When the WLAN module and the Bluetooth module are operating simultaneously in the same area, as shown inFIG. 1, and a BT 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 WLAN module and BT module share the same spectrum and also share a single antenna, preventing interference therebetween is required.

FIG. 3is a schematic diagram illustrating operation conflicts occurring between WLAN and BT communication services sharing a single antenna. InFIG. 3, the shared single antenna is switched between WLAN and BT communication services in a given time slot for transceiving data. If the BT communication service carries audio data that requires real-time transmission, for example, Synchronous Connection-Oriented (SCO) packets, the BT 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 BT transceiving process, a time slot will be assigned to the BT transceiving process and the WLAN transceiving process will be blocked. As shown inFIG. 3, the WLAN receiving operation (Rx operation)1occurs in the time slot, while the BT communication service is idle. Therefore, the Rx operation1is performed without interference and an acknowledgement (ACK) message2is sent to the WLAN AP (such as the AP inFIG. 1) as a reply message indicating that the Rx operation1has been completed. Following the Rx operation1, another WLAN Rx operation3is performed. The Rx operation3is also performed without interference because the BT communication service is in the idle state. However, an ACK message4in response to the Rx operation3can not be replied to the WLAN AP, as its time slot has already been assigned to the Bluetooth transmitting operation (Tx operation). Accordingly, the Rx operation3would be determined to have failed. In response to the failure, the WLAN AP would re-transmit the data frame 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 operation3(denoted as5), with a prolonged operation period, would be more likely to overlap with the BT transceiving process. Thus, data frame would once again be re-transmitted with an even lower data rate than that for the prior re-transmitted data, which would cause even more overlap with the BT transceiving process than the prior attempt. As a result, because the WLAN and BT wireless communication services sharing a single antenna are time-division accessed (i.e., only one communication service of WLAN and BT can be enabled at each time slot), throughput of the WLAN is greatly hindered.

BRIEF SUMMARY OF THE INVENTION

In light of the previously described problems, there exists a need for a method and system, in which coexistence of a plurality of wireless communication modules sharing a single antenna is provided for simultaneous operations thereof.

One aspect of the invention discloses a wireless communications system, comprising a first wireless communications module, a second wireless communications module, and an RF module. The first wireless communications module is configured to transmit or receive a first wireless signal and the second wireless communications module is configured to transmit or receive a second wireless signal. The RF module is configured to allocate a first transceiving path and a second transceiving path to the first wireless communications module and the second wireless communications module, respectively, to enable the transmission or reception of the first wireless signal and the second wireless signal at the same time.

Another aspect of the invention discloses a method for coexistence of a plurality of wireless communications modules in a wireless communications device. The method comprises the steps of: determining whether a first wireless communications module is transmitting or receiving a first wireless signal, and a second wireless communications module is transmitting or receiving a second wireless signal; and allocating a first transceiving path and a second transceiving path to the first wireless communications module and the second wireless communications module, respectively, to enable the transmission or reception of the first wireless signal and the second wireless signal at the same time.

Other aspects and features of the invention will become apparent to those with ordinary skill in the art upon review of the following descriptions of specific embodiments of the wireless communications system, and the method for the coexistence of a plurality of wireless communications modules in a wireless communications device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 4is a block diagram illustrating a wireless communications system according to an embodiment of the invention. The system400comprises a WLAN module410, a BT module420, an RF module430, and an antenna440. The WLAN module410provides the functionality of WLAN communications (such as WiFi communications) via the antenna440, while the BT module420provides the functionality of BT communications via the antenna440. Specifically, the WLAN module410may be configured to transmit or receive WLAN signals, and the BT module420may be configured to transmit or receive BT signals. Both of the WLAN module410and the BT module420may contain a processing unit, such as a general-purposed processor or a micro-control unit (MCU), to load and execute a series of program codes of the respective wireless communication protocol from a storage unit to provide functionalities for respective wireless communications. The antenna440is configured to operate at 2.4 GHz license-free frequency band. The RF module430comprises a connection device431and a logic unit432. The connection device431comprises a plurality of transceiving paths for connecting the WLAN module410and the BT module420to the antenna440. The logic unit432controls the allocations of the transceiving paths in the connection device431to the WLAN module410and the BT module420. Specifically, the logic unit432allocates a first transceiving path and a second transceiving path in the connection device431to the WLAN module410and the BT module420, respectively, to enable the transmission or reception of the WLAN signals and the BT signals at the same time. The RF module430may further comprise multiple function units or hardware components for processing the receiving or transmitting wireless signals. It is to be understood that the antenna440may be disposed outside of the wireless communications system400or the WLAN module410and the BT module420may be integrated into a wireless communications chipset, and the invention is not limited thereto.

The connection device431may comprise three ports12,14and16, and may be configured to couple the ports12and14to form a transceiving path (through path), and to couple the ports12and16to form another transceiving path (coupled path), wherein the port14is isolated from the port16by substantially 20 dB and the electrical signals passing through the path between ports12and16are substantially attenuated by 6 or 10 dB. Referring toFIG. 5A, the connection device431may contain an attenuator attenuating electrical signals passing through the ports12and16by 20 dB. Alternatively, the connection device431may contain a directional coupler, as shown inFIG. 5B, in which the ports12and14are coupled as a through path, the port16and an external node18are connected as a through path, the ports12and16are coupled as a coupled path, and the ports14and16are isolated with a loss around 20-40 dB. The through path is direct or indirect through and the external node18may be a resistor (for example, a 50Ω resistor or a 50Ω equivalent termination). Note that the through path between the ports12and14may have a path loss of 0.5 dB, substantially while the coupled path between ports12and16may have a path loss of 10 dB substantially, or the through path between ports12and14may have a path loss of 1.2 dB substantially, while the coupled path between ports12and16may have a path loss of 6 dB substantially.

FIG. 6AandFIG. 6Billustrate two embodiments of the directional coupler shown inFIG. 5B. Referring toFIG. 6A, two transmission lines are set sufficiently close together, such that electrical signals (or energy) directed from the port12(connected to a port called an input port) to the port14(connected to a port called a transmitted port) is coupled to the port16(connected to a port called a coupled port). Similarly, referring toFIG. 6B, electrical signals (or energy) directed from the ports16(connected to a port called an input port) to a transmitted port (such as port18inFIG. 5B) is coupled to the port12(connected to a port called a coupled port) and isolated from the port14(connected to a port called an isolated port), such that the coupled signals can be added to electrical signals passing between the ports12and14.

In addition to the attenuator (FIG. 5A) and the directional coupler (FIG. 5B), the connection device431may be implemented in a power divider, in which the ports14and16are isolated and both ideally have a path loss of 3 dB (3.5 dB in practice). Furthermore, the connection device431may be implemented in a power splitter. The structure of the power splitter is similar to that of the power divider, but with different path losses between the output ports. For a power splitter, the path loss at the ports14and16are different. For example, the port16may have a path loss of 10 dB while the port14may have a path loss of 0.5 dB, or the port16may have a path loss of 6 dB while the port14may have a path loss of 1 dB. For the coupling values of the power splitter, reference may be made to the Table 1 below:

The transceiving paths in the connection device431have different path losses, and the allocation of the transceiving paths to the WLAN module410and the BT module420may be determined by the logic unit432according to the operation statuses of the WLAN module410and/or the BT module420. Table 2 below depicts exemplary allocations of the transceiving paths in the connection device431according to an embodiment of the invention:

TABLE 2Operation Status of theOperation StatusWLAN module 410of the BT module 420OFFONOFFNULLAllocate the through pathto WLAN moduleONAllocate the throughCheck on the signalpath to BT moduleindicators of the WLANand BT signals

In Table 2 above, “ON” indicates that the WLAN module410or the BT module420is activated (i.e. the WLAN function or the BT function is turned on), and “OFF” indicates that the WLAN module410or the BT module420is de-activated (i.e. the WLAN function or the BT function is turned off) “NULL” means that the allocations of the transceiving paths are not necessary since both of the WLAN module410and the BT module420are not performing wireless signal transmission or reception. Note that the through path, which has lower path loss, is allocated to the WLAN module410or the BT module420if only one of the WLAN module410or the BT module420is performing the wireless signal transmission or reception. Note that, if both the WLAN module410and the BT module420are activated, the logic unit432may need to check on the signal indicators of the WLAN and BT signals. Further description regarding the allocations of the transceiving paths will be explained below in more detail with references to the flowchart inFIG. 7.

FIG. 7is a flowchart illustrating the method for the coexistence of the WLAN module410and the BT module420according to an embodiment of the invention. The method begins by inquiring about the operation statuses of the WLAN module410and/or the BT module420, to determine whether WLAN function is turned on/off, and/or whether the BT function is turned on/off (step S701). In addition to information concerning whether the WLAN function or the BT function is turned on, the operation statuses can also include information concerning whether WLAN/Bluetooth carries data for real-time applications or non real-time applications. Next, the logic unit432further determines the signal indicators of the WLAN signals and/or the BT signals, or receives the signal indicators of the WLAN signals and/or the BT signals from other module such as an additional processor not shown inFIG. 4(step S702). The signal indicators may be received signal strength indications (RSSI), signal to noise ratios (SNR), interference to signal ratios (ISR), adjacent channel interferences (ACI), packet error rates (PER), or bit error rates (BER) of the WLAN signals and/or the BT signals. Alternatively, the signal indicators may contain more than one of the RSSI, SNR, ISR, ACI, PER, and BER of the WLAN signals and/or the BT signals. In this embodiment, the RSSI is taken as the signal indicator for the WLAN and BT signals. The logic unit432further selects a set of thresholds for determining whether the WLAN signals and the BT signals are in good condition according to the operation statuses of the WLAN module410and the BT module420(step S703), wherein the thresholds are adjustable. Specifically, a set of thresholds may be selected for the BT signals of real-time applications, while another set of thresholds may be selected for the BT signals of non real-time applications. The real-time application, for example, includes SCO and A2DP applications.FIGS. 8A and 8Bare schematic diagrams illustrating the sets of thresholds for real-time BT applications and non real-time BT applications according to an embodiment of the invention. As shown inFIGS. 8A and 8B, each set of thresholds includes one BT threshold and two WLAN thresholds used as signal quality criteria, wherein T1and T1′ represent the BT thresholds and T2, T2′, and T3, T3′ represent the first and second WLAN thresholds. Note that the BT signals for real-time applications are taken as an example forFIG. 8Aand the BT signals for non real-time applications are taken as an example forFIG. 8B, and both ofFIGS. 8A and 8Bshow the thresholds with respect to the RSSI, being taken as the signal indicator for the WLAN and BT signals. However, other signal quality indicators, such as the SNR, ISR, ACI, PER, and BER of the WLAN and BT signals, may be used as well for the selection of the set of thresholds with different requirements of the respective signal quality indicators.

Subsequently, the logic unit432may determine the signal quality of the BT signals by checking if the RSSI of the BT signals is greater than the BT threshold in the selected set of thresholds (step S704). That is, if the selected set of thresholds is the set of thresholds as shown inFIG. 8A, then the logic unit432may compare the RSSI of the BT signals to T1, and if the selected set of thresholds is the set of thresholds as shown inFIG. 8B, then the logic unit432may compare the RSSI of the BT signals to T1′. Subsequent to step S704, if so, the logic unit432may determine the signal quality of the WLAN signals by checking if the RSSI of the WLAN signals is greater than the first WLAN threshold in the selected set of thresholds (step S705). That is, if the selected set of thresholds is the set of thresholds as shown inFIG. 8A, then the logic unit432may compare the RSSI of the WLAN signals to T2; and if the selected set of thresholds is the set of thresholds as shown inFIG. 8B, then the logic unit432may compare the RSSI of the WLAN signals to T2′. If the RSSI of the WLAN signals is greater than the first WLAN threshold in the selected set of thresholds, the logic unit432may allocate the through path and coupled path to the BT module420and the WLAN module410, respectively (step S706). Otherwise, the logic unit432may allocate the through path and coupled path to the WLAN module410and the BT module420, respectively (step S707). Subsequent to step S704, if not, the logic unit432may determine the signal quality of the WLAN signals by checking if the RSSI of the WLAN signals is greater than the second WLAN threshold in the selected set of thresholds (step S708). That is, if the selected set of thresholds is the set of thresholds as shown in FIG.8A, then the logic unit432may compare the RSSI of the WLAN signals to T3, and if the selected set of thresholds is the set of thresholds as shown inFIG. 8B, then the logic unit432may compare the RSSI of the WLAN signals to T3′. If the RSSI of the WLAN signals is greater than the second WLAN threshold in the selected set of thresholds, the logic unit432may allocate the through path and coupled path to the BT module420and the WLAN module410, respectively (step S709). Otherwise, the logic unit432may also allocate the through path and coupled path to the BT module420and the WLAN module410, respectively, by further coordination between the WLAN module410and the BT module420(step S710).

In step S710, the further coordination between the WLAN module410and the BT module420may be required due to the fact that both of the WLAN signals and the BT signals have bad signal quality (i.e. the RSSIs are below the respective thresholds) and may not withstand the coexistence interference from each other. To further clarify, the logic unit432may collect the potential Tx/Rx operations of the WLAN module410and the BT module420in an upcoming period of time, and then arbitrate which one of the WLAN module410and the BT module420will be able to obtain the usage of the antenna440if a collision occurs in an upcoming period of time. If the WLAN module410is granted to obtain usage of the antenna440, then the Tx/Rx operations of the WLAN module410may be performed while the Tx/Rx operations of the BT module420are suspended. Otherwise, if the BT module420is granted to obtain the usage of the antenna440, then the Tx/Rx operations of the BT module420may be performed while the Tx/Rx operations of the WLAN module410are suspended. Accordingly, the coexistence interference may be prevented and the signal qualities of the WLAN and BT signals may be assured. Without departing from the spirit of the invention, other embodiments of the method for the coexistence of a BT module and a WiMAX/LTE module, or the coexistence of a WLAN module and a WiMAX/LTE module, may be contemplated with relevant modifications according to the architectures inFIG. 4and the control flow inFIG. 7.

Note that the peer BT device, which the wireless communications system400is communicating with via the BT module420, may dynamically change its transmission power, and variations on the signal indicator of the received BT signals in the wireless communications system400may occur. This may further cause changes to the allocation of the transceiving paths of the WLAN module410and the BT module420, and even cause system performance degression if the changes occur too often. In order to prevent constant variations on the signal indicator of the received BT signals, the BT module420may further request the peer BT device to keep a fixed transmission power for the transmission of the BT signals. In addition, the distance between the peer BT device or the WLAN AP and the wireless communications system400may be taken into account for the allocations of the transceiving paths. For example, if the distance between the peer BT device and the wireless communications system400is far, the logic unit432may allocate the through path to the BT module420to minimize loss of the BT signals; and if the distance between the peer BT device and the wireless communications system400is near and the distance between the WLAN AP and the wireless communications system400is far, the logic unit432may allocate the through path to the WLAN module410to minimize the loss of WLAN signals. The distance between the peer BT device or the WLAN AP and the wireless communications system400may be determined according to the signal indicators of the WLAN signals or the BT signals. For example, a high RSSI of the BT signals may indicate that the peer BT device is near the wireless communications system400, and a low RSSI of the BT signals may indicate that the peer BT device is far away from the wireless communications system400.

Subsequently, the logic unit432may determine the signal quality of the BT signals by checking if the RSSI of the BT signals is greater than the BT threshold in the selected set of thresholds (step S704). That is, if the selected set of thresholds is the set of thresholds as shown inFIG. 8A, then the logic unit432may compare the RSSI of the BT signals to T1, and if the selected set of thresholds is the set of thresholds as shown inFIG. 8B, then the logic unit432may compare the RSSI of the BT signals to T1′. Subsequent to step S704, if so, the logic unit432may determine the signal quality of the WLAN signals by checking if the RSSI of the WLAN signals is greater than the first WLAN threshold in the selected set of thresholds (step S705). That is, if the selected set of thresholds is the set of thresholds as shown inFIG. 8A, then the logic unit432may compare the RSSI of the WLAN signals to T2; and if the selected set of thresholds is the set of thresholds as shown inFIG. 8B, then the logic unit432may compare the RSSI of the WLAN signals to T2′. If the RSSI of the WLAN signals is greater than the first WLAN threshold in the selected set of thresholds, the logic unit432may allocate the through path and coupled path to the BT module420and the WLAN module410, respectively (step S706). Otherwise, the logic unit432may allocate the through path and coupled path to the WLAN module410and the BT module420, respectively (step S707). Subsequent to step S704, if not, the logic unit432may determine the signal quality of the WLAN signals by checking if the RSSI of the WLAN signals is greater than the second WLAN threshold in the selected set of thresholds (step S708). That is, if the selected set of thresholds is the set of thresholds as shown inFIG. 8A, then the logic unit432may compare the RSSI of the WLAN signals to T3, and if the selected set of thresholds is the set of thresholds as shown inFIG. 8B, then the logic unit432may compare the RSSI of the WLAN signals to T3′. If the RSSI of the WLAN signals is greater than the second WLAN threshold in the selected set of thresholds, the logic unit432may allocate the through path and coupled path to the BT module420and the WLAN module410, respectively (step S709). Otherwise, the logic unit432may also allocate the through path and coupled path to the BT module420and the WLAN module410, respectively, with further coordination between the WLAN module410and the BT module420(step S710).