Abstract:
A network interface includes a radio frequency system and a media access controller. The media access controller includes first and second client modules and a control module. Each of the client modules wirelessly communicates with a network via the radio frequency system and the antenna. Each of the client modules is controllable to be in an active state or a sleep state. The control module determines priority levels of the first client module and the second client module. The control module also, based on the priority levels, (i) controls the first client module to be in the active state to permit communication between the first client module and the radio frequency system, and (ii) controls the second client module to be in the sleep state to prevent communication between the second client module and the radio frequency system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/586,859, filed on Oct. 26, 2006, which claims the benefit of claims the benefit of U.S. Provisional Application Nos. 60/748,937, filed on Dec. 9, 2005 and 60/808,077, filed on May 24, 2006. The disclosures of the above applications are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     The present disclosure relates to wireless network devices, and more particularly to a coexistence system for wireless network devices having multiple wireless sub-clients that share components. 
     BACKGROUND 
     In a Wireless Local Area Network (WLAN), client stations can communicate with other client stations in an ad hoc mode or with an access point (AP) in an infrastructure mode. WLANs typically have a range in the hundreds of feet. The client stations typically include a wireless network interface that is associated with a host device. The host device can be a desktop computer, a personal digital assistant (PDA), a mobile phone, a laptop, a personal computer (PC), a printer, a digital camera, an internet protocol (IP) phone, etc. The AP provides connectivity to a network, such as the Internet or other network. 
     The wireless network interface may be compatible with Worldwide Interoperability for Microwave Access (WiMAX). WiMAX systems schedule communications with client stations by allocating a time slot. Initially, the client station registers with a base station. The base station transmits MAPs that indicate when the client station should transmit and receive data. When the WiMAX client does not transmit or receive data during the regularly scheduled MAP, the base station may deregister the client. Bluetooth is another wireless standard that operates at shorter ranges than WLAN. 
     When implemented by the same device, WiMAX, WLAN, and Bluetooth clients may share components to reduce the cost of the device. Shared components may include the antenna, radio frequency (RF) subsystems, such as transmitters and receivers, baseband processors, etc. The sharing of components should be coordinated. Further, WiMAX, WiFi, and Bluetooth may use the same frequency or nearby frequencies, which may cause interference. 
     SUMMARY 
     A network interface is provided and includes a radio frequency system connected to an antenna and a media access controller. The media access controller includes client modules and a control module. The client modules include a first client module and a second client module. Each of the client modules wirelessly communicates with a network via (i) the radio frequency system and (ii) the antenna. Each of the client modules is controllable to be in an active state or a sleep state. The control module is configured to (i) determine a first priority level of the first client module, and (ii) determine a second priority level of the second client module. The control module is also configured to, based on the first priority level and the second priority level, (i) control the first client module to be in the active state to permit communication between the first client module and the radio frequency system, and (ii) control the second client module to be in the sleep state to prevent communication between the second client module and the radio frequency system. 
     A wireless network interface includes a component, a first sub-client module that operates using a first wireless protocol, and a second sub-client module that operates using a second wireless protocol. The first and second wireless protocols are different. The first and second sub-client modules share use of the component. A component sharing control module selectively transitions the first sub-client module into and out of a state to allow the second sub-client module to use the component during the state. 
     In another feature, at least one of the first sub-client module and the second sub-client module includes an active sub-client. At least one of the first sub-client module and the second sub-client module includes at least one of a Worldwide Interoperability for Microwave Access (WiMAX) sub-client module, a Wireless Local Area Network (WLAN) sub-client module, and a Bluetooth sub-client module. 
     In other features, the state includes a sleep state. The first sub-client module sends a signal to the second sub-client module indicating the first sub-client module is entering the sleep state. At least one of the first sub-client module and the component sharing control module prevents the second sub-client module from using the component within a predetermined time in which the first sub-client module is scheduled to receive a transmission. 
     In other features, the component includes at least one of an antenna and a radio frequency (RF) subsystem. The RF subsystem includes at least one of a filter, a switch, a transmitter (Tx), a receiver (Rx), and a base band processor (BBP) module. The first sub-client module selectively reduces signal power to decrease signal interference with signals from the second sub-client module. 
     In other features, at least one of the first sub-client module and the component sharing control module prevents the second sub-client module from receiving transmissions within a predetermined time in which the first sub-client module is scheduled to receive a transmission. The state includes at least one of an idle state and a low power state. 
     In still other features, the first sub-client module includes a WiMAX sub-client module and the second sub-client module includes a WLAN sub-client module. The WLAN sub-client module transmits a reserve signal to the component sharing control module to reserve the component for a duration of time when the WiMAX sub-client module is due to receive a MAP. The reserve signal includes a CTS-Self protocol. The WLAN sub-client module receives transmissions from a network. The WLAN sub-client module sends transmissions to a network. 
     In other features, a system includes the wireless network interface and a base station that communicates with a network. The WiMAX sub-client module transmits a busy signal to the base station during WLAN sub-client module use of the component. 
     In other features, a system includes the wireless network interface. The WLAN sub-client module detects a WiMAX signal through at least one of a repeated MAP transmission and a signal from the WiMAX sub-client module. The system further includes a first access point (AP) for the WLAN sub-client module. The WLAN sub-client module informs the first AP of interference with the WiMAX signal and that the first AP should switch transmission channels. The WLAN sub-client module scans for a second AP. 
     In still other features, the first sub-client module includes a WLAN sub-client module and the second sub-client module includes a WiMAX sub-client module. The component includes radio frequency (RF) subsystems that selectively switch from a WLAN frequency to a WiMAX frequency during the state. The WLAN sub-client module periodically receives signals during the state. At least one of the periodic signals is skipped when the WiMAX sub-client module is due to receive signals. The component sharing control module selectively determines the state with a base station when WLAN sub-client module network connection quality is above a WLAN network disconnect threshold. The base station communicates with the WiMAX sub-client module. The component sharing control module includes a medium access control module (MAC). 
     In other features, a system includes the wireless network interface and further includes access points (AP) and base stations. The MAC includes a mobility manager module that selectively connects the first sub-client module and the second sub-client module to each of the APs and base stations. The MAC further includes a coexistence control module that controls states of the first sub-client module and the second sub-client module. The states comprise idle, scan, network entry, registered, and active. The coexistence control module determines which of the first sub-client and the second sub-client has priority for the component and controls the selective transitions based on the priority. 
     In still other features, a wireless network interface method includes operating a first sub-client module using a first wireless protocol and operating a second sub-client module using a second wireless protocol. The first and second wireless protocols are different. The first and second sub-client modules share use of component. The method selectively transitions the first sub-client module into and out of a state to allow the second sub-client module to use the component during the state. 
     In a wireless network interface method, at least one of the first sub-client module and the second sub-client module includes an active sub-client. At least one of the first sub-client module and the second sub-client module includes at least one of a WiMAX sub-client module, a WLAN sub-client module, and a Bluetooth sub-client module. In the wireless network interface method, selectively transitioning the first sub-client module into and out of the state includes selectively transitioning the first sub-client module into and out of a sleep state. 
     In other features, the first sub-client module sends a signal to the second sub-client module indicating the first sub-client module is entering the sleep state. The wireless network interface method further includes preventing the second sub-client module from using the component within a predetermined time in which the first sub-client module is scheduled to receive a transmission. The component includes at least one of an antenna and an RF subsystem. 
     In other features, the RF subsystem includes at least one of a filter, a switch, a Tx, an Rx, and a BBP module. The wireless network interface method further includes selectively reducing signal power to decrease signal interference with signals from the second sub-client module. The wireless network interface method further includes preventing the second sub-client module from receiving transmissions within a predetermined time in which the first sub-client module is scheduled to receive a transmission. Selectively transitioning the first sub-client module into and out of the state includes selectively transitioning the first sub-client module into and out of at least one of an idle state and a low power state. 
     In other features, the first sub-client module includes a WiMAX sub-client module and the second sub-client module includes a WLAN sub-client module. The wireless network interface method further includes transmitting a reserve signal to the component sharing control module. The method also includes reserving the component for a duration of time when the WiMAX sub-client module is due to receive a MAP. For the wireless network interface method, the reserve signal includes a CTS-Self protocol. The WLAN sub-client module receives transmissions from a network. The WLAN sub-client module sends transmissions to a network, and a base station communicates with the network. The WiMAX sub-client module transmits a busy signal to the base station during WLAN sub-client module use of the component. 
     In other features, the wireless network interface method further includes detecting a WiMAX signal through at least one of a repeated MAP transmission and a signal from the WiMAX sub-client module. The method further includes informing the first AP of interference with the WiMAX signal and that the first AP should switch transmission channels. The method further includes scanning for a second AP. 
     In still other features, the first sub-client module includes a WLAN sub-client module and the second sub-client module includes a WiMAX sub-client module. The wireless network interface method further includes selectively switching from a WLAN frequency to a WiMAX frequency during the state. The wireless network interface method further includes the WLAN sub-client module periodically receiving signals during the state. The wireless network interface method further includes skipping at least one of the periodic signals when the WiMAX sub-client module is due to receive signals. The wireless network interface method further includes selectively determining the state with a base station when WLAN sub-client module network connection quality is above a WLAN network disconnect threshold. 
     In other features, the component sharing control module includes a medium MAC. The wireless network interface method further includes a mobility manager module within the MAC selectively connecting the first sub-client module and the second sub-client module to each of multiple APs and base stations. The method further includes a coexistence control module within the MAC controlling states of the first sub-client module and the second sub-client module. The states comprise idle, scan, network entry, registered, and active. The method further includes determining which of the first sub-client and the second sub-client has priority for the component, and controlling the selective transitions based on the priority. 
     In still other features, a wireless network interface includes a component for interacting with a network. The interface includes first sub-client module for operating with a first wireless protocol and second sub-client module for operating with a second wireless protocol. First and second wireless protocols are different. The first and second sub-client module share use of the component. The interface also includes component sharing module for selectively transitioning the first sub-client module into and out of a state to allow the second sub-client module to use the component during the state. 
     In other features, at least one of the first sub-client module and the second sub-client module is active. At least one of the first sub-client module and the second sub-client module includes at least one of sub-client module for using WiMAX, sub-client module for using WLAN, and sub-client module for using Bluetooth. 
     In other features, the state includes a sleep state. The first sub-client module sends a signal to the second sub-client module indicating the first sub-client module is entering the sleep state. At least one of the first sub-client module and the component sharing module prevents the second sub-client module from using the component within a predetermined time. The predetermined time is the duration during which the first sub-client module is scheduled to receive a transmission. 
     The component includes at least one of antenna for receiving signals and RF subsystem for processing the signals. The RF subsystem includes at least one of filter for filtering the signals, switch for forwarding the signals, transmitter for transmitting the signals, receiver for receiving the signals, and base band processor for processing a base band of the signals. The first sub-client module selectively reduces signal power to decrease signal interference with signals from the second sub-client module. 
     At least one of the first sub-client module and the component sharing module prevents the second sub-client module from receiving transmissions within a predetermined time in which the first sub-client module is scheduled to receive a transmission. The state includes at least one of an idle state and a low power state. 
     The first sub-client module includes sub-client module for using WiMAX and the second sub-client module includes sub-client module for using a WLAN. The WLAN sub-client module transmits a reserve signal to the component sharing module to reserve the component for a duration of time when the WiMAX sub-client module is due to receive a MAP. The reserve signal includes a CTS-Self protocol. The WLAN sub-client module receives transmissions from network for communicating between devices. The WLAN sub-client module sends transmissions to the network. 
     In other features, a system includes the wireless network interface. The system also includes a base station for communicating with the network. The WiMAX sub-client module transmits a busy signal to the base station during WLAN sub-client module use of the component. 
     In other features, the WLAN sub-client module detects a WiMAX signal through at least one of a repeated MAP transmission and a signal from the WiMAX sub-client module. The system further includes a first AP for accessing the network for the WLAN sub-client module. The WLAN sub-client module informs the first AP of interference with the WiMAX signal and that the first AP should switch transmission channels. The WLAN sub-client module scans for a second AP for accessing the network. 
     In still other features, the first sub-client module includes sub-client module for operating WLAN and the second sub-client module includes sub-client module for operating WiMAX. The component includes radio frequency (RF) subsystems that selectively switch from a WLAN frequency to a WiMAX frequency during the state. The WLAN sub-client module periodically receives signals during the state. At least one of the periodic signals is skipped when the WiMAX sub-client module is due to receive signals. The component sharing module selectively determines the state with base station for communicating with the network when network connection quality for the WLAN sub-client module is above a WLAN network disconnect threshold. The base station communicates with the WiMAX sub-client module. The component sharing module includes a MAC for accessing the network. 
     In other features, a system includes the wireless network interface and further includes APs for accessing the network and base station for accessing the network. The MAC includes mobility manager module for selectively connecting the first sub-client module and the second sub-client module to each of the APs and the base station. The MAC further includes coexistence control module for controlling states of the first sub-client module and the second sub-client module. The states comprise idle, scan, network entry, registered, and active. The coexistence control module determines which of the first sub-client module and the second sub-client module has priority for the component and controls the selective transitions based on the priority. 
     In still other features, a computer program stored for use by a processor for operating a wireless network interface includes operating a first sub-client module using a first wireless protocol and operating a second sub-client module using a second wireless protocol. The first and second wireless protocols are different. The first and second sub-client modules share use of a component. The computer program selectively transitions the first sub-client module into and out of a state to allow the second sub-client module to use the component during the state. 
     In other features, at least one of the first sub-client module and the second sub-client module includes an active sub-client. At least one of the first sub-client module and the second sub-client module includes at least one of a WiMAX sub-client module, a WLAN sub-client module, and a Bluetooth sub-client module. In the computer program, selectively transitioning the first sub-client module into and out of the state includes selectively transitioning the first sub-client module into and out of a sleep state. 
     In other features, the first sub-client module sends a signal to the second sub-client module indicating the first sub-client module is entering the sleep state. The computer program further includes preventing the second sub-client module from using the component within a predetermined time in which the first sub-client module is scheduled to receive a transmission. The component includes at least one of an antenna and a radio frequency (RF) subsystem. 
     In other features, the RF subsystem includes at least one of a filter, a switch, a Tx, an Rx, and a BBP module. The computer program further includes selectively reducing signal power to decrease signal interference with signals from the second sub-client module. The computer program further includes preventing the second sub-client module from receiving transmissions within a predetermined time in which the first sub-client module is scheduled to receive a transmission. The computer program selectively transitions the first sub-client module into and out off at least one of an idle state and a low power state. 
     In other features, the first sub-client module includes a WiMAX sub-client module and the second sub-client module includes a WLAN sub-client module. The computer program further includes transmitting a reserve signal to the component sharing control module. The computer program also reserves the component for a duration of time when the WiMAX sub-client module is due to receive a MAP. The reserve signal includes a CTS-Self protocol. 
     In other features, the WLAN sub-client module receives transmissions from a network, and the WLAN sub-client module sends transmissions to a network. A base station communicates with a network, and the WiMAX sub-client module transmits a busy signal to the base station during WLAN sub-client module use of the component. 
     In other features, the computer program further includes detecting a WiMAX signal through at least one of a repeated MAP transmission and a signal from the WiMAX sub-client module. The computer program further includes informing the first AP of interference with the WiMAX signal and that the first AP should switch transmission channels. The computer program further includes scanning for a second AP. 
     In other features, the first sub-client module includes a WLAN sub-client module and the second sub-client module includes a WiMAX sub-client module. The computer program further includes selectively switching from a WLAN frequency to a WiMAX frequency during the state. The computer program further includes the WLAN sub-client module periodically receiving signals during the state. The computer program further includes skipping at least one of the periodic signals when the WiMAX sub-client module is due to receive signals. The computer program further includes selectively determining the state with a base station when WLAN sub-client module network connection quality is above a WLAN network disconnect threshold. 
     In other features, the component sharing control module includes a medium MAC. The computer program further includes selectively connecting the first sub-client module and the second sub-client module to each of multiple APs and base stations. The computer program further includes controlling states of the first sub-client module and the second sub-client module. The states comprise idle, scan, network entry, registered, and active. The computer program further includes determining which of the first sub-client and the second sub-client has priority for the component and controlling the selective transitions based on the priority. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of a coexistence system for wireless network devices; 
         FIG. 2  is a sequence diagram illustrating a method for sharing components; 
         FIG. 3  is a state transition diagram for a WLAN sub-client; 
         FIG. 4  is a state transition diagram for a WiMAX sub-client; 
         FIG. 5  is a sequence diagram illustrating a method for sharing components; 
         FIG. 6  is a sequence diagram illustrating a method for sharing components; 
         FIG. 7  is a block diagram illustrating a method for supporting coexistence of multiple sub-clients; 
         FIG. 8  is a block diagram illustrating a method for handoff of components between multiple sub-clients; 
         FIG. 9  is WiMAX signal time frame diagram including scheduled WLAN activation periods; 
         FIG. 10  is a protocol diagram for Unsolicited Automatic Power Save Delivery (U-APSD) for a WLAN sub-client; 
         FIG. 11A  is a functional block diagram of a vehicle control system; 
         FIG. 11B  is a functional block diagram of a cellular phone; 
         FIG. 11C  is a functional block diagram of a set top box; and 
         FIG. 11D  is a functional block diagram of a media player. 
     
    
    
     DESCRIPTION 
     The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module, circuit and/or device refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure. 
     The present disclosure includes a coexistence system and method for wireless network devices with wireless network interfaces that support a variety of sub-clients including, for example, a Wireless Local Area Network (WLAN) sub-client, a Worldwide Interoperability for Microwave Access (WiMAX) sub-client, and a Bluetooth (BT) sub-client, which share components. 
     Referring now to  FIG. 1 , a coexistence system  10  for wireless network devices having multiple sub-clients that share components is shown. Wireless access points (AP)  12 - 1 ,  12 - 2 , . . . , and  12 -X (collectively APs  12 ) and/or base stations  13 - 1 ,  13 - 2 , . . . , and  13 -X (collectively base stations  13 ) provide connections between a host  14  having a wireless network interface  16  and networks  18 - 1 ,  18 - 2 , . . . , and  18 -Z, that may include the Internet  19 . The APs  12  and base stations  13  may communicate with the networks through associated routers  20 - 1 ,  20 - 2 , . . . , and  20 -Z. The wireless network interface  16  communicates with the APs  12 , the base stations  13  and/or other wireless client stations  17 . The host  14  may be a personal digital assistant (PDA), mobile phone, laptop, personal computer (PC), printer, digital camera, or internet protocol (IP) phone. 
     The wireless network interface  16  may include shared components such as an antenna  22 , radio frequency (RF) subsystems  23  (such as a filter  24 , a switch  25 , a transmitter (Tx)  26 , a receiver (Rx)  27 , and/or a base band processor (BBP) module  28 ). Further, each sub-client may include an antenna, a filter, a switch, a Tx, an Rx, and/or a BBP module. The wireless communications can be compliant with various protocols including at least one of the Institute of Electrical and Electronics Engineers (IEEE) standards 802.11, 802.11a, 802.11b, 802.11g, 802.11h, 802.11n, 802.16, 802.16a, 802.16e, 802.16-2004, and 802.20, and/or the Bluetooth standard published by the Bluetooth Special Interest Group (SIG). The aforementioned standards are hereby incorporated by reference in their entirety. 
     The antenna  22  and RF subsystems  23  communicate with a media access control module (MAC)  29 , which is also referred to herein as a component sharing control module. The MAC  29  may include a mobility manager module  30  that receives information about the availability and signal strength of the APs  12  and/or base stations  13 . The mobility manager module  30  also selects one of the sub-clients to connect to the appropriate AP  12  and/or base station  13  and informs a coexistence control module  31 . Illustrated are a WLAN (WiFi) sub-client module  32 , a WiMAX sub-client module  34 , and/or a Bluetooth sub-client module  35 . The MAC  29  communicates with the host  14  through I/O modules  33 ,  37  and also communicates with a processor module  38 , which may perform processing for the network interface  16 . 
     The WLAN, WiMAX, and Bluetooth sub-client modules  32 ,  34 ,  35  may be in various states or modes, such as, but not limited to, idle, scan, network entry, registered, and active. These states may be controlled by the coexistence control module  31  or the sub-client modules  32 ,  34 . When in the idle state, a sub-client module  32 ,  34  is not connected to an AP or base station and is also not scanning. When in the scan state, the sub-client module  32 ,  34  is not connected to an AP or base station but is receiving beacons or MAPs. When in the network entry state, the sub-client module  32 ,  34  has identified an AP or base station and is in the process of undergoing network entry to register with the AP or base station. When in the registered state, the sub-client module  32 ,  34  has completed network entry and has registered to the AP or base station but is not passing user data. When in the active state, the sub-client module  32 ,  34  is passing user data. When multiple wireless access devices are in a single handheld device, the coexistence control module  31  limits network entry to one sub-client module at a time. Further, the sub-client modules  32 ,  34  can transition to any other states independently to avoid simultaneous active state interference. Regardless of the state, when transmitting and/or receiving, the sub-client module may require use of shared components (antenna, RF subsystem, etc.). 
     In each state, the power save properties, transmission, and reception requirements are different. In the idle state, both the transmitter and receiver are inactive; and the sub-client module is consuming very low power. In the low power state, which may be any state other than active and idle states, the sub-client module is transmitting or receiving data at a very low rate or not at all. In the active state, the sub-client module is actively transmitting and receiving data. Further, the sub-client modules may enter a sleep state that may include temporarily entering an idle state or a low power state. 
     Referring now to  FIG. 2 , a method  100  for operating the coexistence control module  31  is illustrated. In step  102 , the coexistence control module  31  may define a state of each sub-client module to indicate the activation state of the sub-client module (idle, low power, active) and a priority of the sub-client module for component priority. The component priority may depend on the type of data (voice, non voice, management message etc.) to be transmitted. In step  104 , a first sub-client module may activate (change state to active) when all other sub-clients are idle. In step  106 , the first sub-client module rechecks the state of other sub-clients to verify that no race (i.e. two sub-client modules attempting to use shared components) condition exists. If no other sub-client is competing for the components, in step  108 , the first sub-client module continues using the shared components. Otherwise, in step  110 , the sub-client with higher priority gains access to the shared components. 
     Referring now to  FIG. 3 , a state transition diagram  200  for a WLAN sub-client module  32  is illustrated. In state  202 , after receiving a power up complete signal, the WLAN sub-client module  32  enters an idle state for a predetermined amount of time (or until commanded to scan by the host  14 ) prior to scanning. In state  204 , the WLAN sub-client module  32  enters a scan state to scan for available APs until the coexistence control module  31  commands the WLAN sub-client module  32  to perform network entry with an appropriate AP. In state  206 , the WLAN sub-client module  32  enters the network. 
     In state  208 , after registering with the AP, the WLAN sub-client module  32  enters into a low power state maintaining the connection with the AP but not passing data to the AP. In state  210 , when informed by the coexistence control module  31 , the WLAN sub-client module  32  transitions to the active state to pass user data to the AP. If the WiMAX sub-client module  34  is used for data, the coexistence control module  31  transitions the WLAN sub-client module  32  to a low power state, e.g., a registered state, as in state  208 . If the WLAN link drops, the WLAN sub-client module  32  goes back to the idle state, as in state  202 . In state  212 , the WLAN sub-client module  32  or the AP can deregister the WLAN sub-client module  32 . The WLAN sub-client module  32  can return to the registered state as in state  208 . The WLAN sub-client module  32  can also return to the idle state, as in state  202 , and then scan for available APs. 
     Referring now to  FIG. 4 , a state transition diagram  200  for a WiMAX sub-client module  34  is illustrated. In state  220 , after receiving a power up complete signal, the WiMAX sub-client module  34  enters an idle state for a predetermined amount of time (or until commanded to scan by the host  14 ) prior to scanning. In state  222 , the WiMAX sub-client module  34  enters a scan state to scan for available base stations until the coexistence control module  31  commands the WiMAX sub-client module  34  to enter the network. In state  224 , the WiMAX sub-client module  34  enters the network. 
     In state  226 , after registering with the base station, the WiMAX sub-client module  34  enters into a low power state maintaining the connection with the base station but not passing data to the base station. In state  228 , when informed by the coexistence control module  31 , the WiMAX sub-client module  34  transitions to the active state to pass user data to the base station. If the WLAN sub-client module  32  is used for user data, the coexistence control module  31  transitions the WiMAX sub-client module  34  to a registered state, as in state  226 . If the WiMAX link drops, the WiMAX sub-client module  34  goes back to the idle state, as in state  220 . In state  230 , the WiMAX sub-client module  34  or the base station can deregister the WiMAX sub-client module  34 . The WiMAX sub-client module  34  can return to the registered state as in state  226 . The WiMAX sub-client module  34  can also return to the idle state, as in state  218 , and then scan for available base stations. 
     Referring now to  FIG. 5 , a sequence diagram  250  of a method for sharing components between a low power sub-client  252  and an active sub-client  254  is illustrated. Either or both the low power and active sub-clients may be WiMAX, WLAN, and/or Bluetooth sub-clients. When the low power sub-client  252  requires network interaction, the low power sub-client  252  sends a request  256  to the active sub-client  254  for the shared components. The active sub-client  254  complies with the request  256 , which may include acknowledging pending automatic repeat request (ARQ) packets, informing the AP that the active sub-client  254  will enter a sleep state for a fixed duration, etc. Within a predetermined time  257 , the active sub-client  254  sends an acknowledge signal  258  (ACK). The low power sub-client  252  then performs the intended functions (e.g., transmitting or receiving on the shared components.) and, within a predetermined expiration time  260 , sends a transmit/receive completed message  264  to the active sub-client  254 . The active sub-client  254  then responds with an acknowledge signal  266 . The messages  256 ,  258 ,  264 ,  266  can be sent through a set of registers or shared memory within the host  14 . The sub-clients  252 ,  254  can also use either polling during a common time base or alternately interrupt requests (IRQ) to send and receive the messages  256 ,  258 ,  264 ,  266 . 
     In an alternate example, two sub-clients may be in a low power state. When the first low power sub-client requires the shared components, an interrupt is sent by either the first low power sub-client or the coexistence control module to the second low power sub-client, which activates to service the interrupt. The first low power sub-client can check the status of the second low power sub-client, and when the second low power sub-client is active, the sub-clients may follow the sequence diagram, as shown in  FIG. 5 . When the second low power sub-client is in low power state, the first low power sub-client may take control of the shared components. After completing a transmit/receive, the first low power sub-client may relinquish control of the shared components. 
     In an exemplary embodiment, if the WLAN client knows when the WiMAX client is expecting a MAP, it can transmit a CTS-Self reserving the medium for a fixed duration of time. The WiMAX client can then receive the MAP without WLAN interference. This feature may be applied to ensure reception of all downlink or uplink transmissions. 
     Referring now to  FIG. 6 , an exemplary coexistence system is illustrated. The Bluetooth sub-client  272  is shown interfacing with the WLAN sub-client. When the WLAN sub-client is in an active state, the WLAN sub-client may abort transmissions and transfer shared component access to the Bluetooth sub-client. When the WLAN sub-client is in a low power state, i.e. a low power sub-client  252 , and the WiMAX sub-client is in an active state, i.e. the active sub-client  254 , the Bluetooth sub-client  272  may send a priority request  274  to the WLAN low power sub-client  252  for access to the shared components. This request  274  may include setting a clear channel assessment (CCA) signal of the WLAN sub-client high. When a clear channel assessment signal is held high, the WiMAX active sub-client  254  may abort active state transmissions of units of data (packets). The WiMAX re-transmits the units of data at a later scheduled transmission period. 
     Within the predetermined time  257 , the active (WiMAX) sub-client  254  sends an acknowledge signal  258 . The low power (WLAN) sub-client  252  then sends an acknowledgement signal  276  to the Bluetooth sub-client  272 , which performs the intended functions  278  (e.g., transmitting or receiving on the shared components.). The low power sub-client  252 , within the predetermined expiration time  260 , sends a signal  280  indicating that the low power sub-client  252  is resuming control of the components. The low power sub-client  252  then sends a transmit/receive completed message  264  to the active sub-client  254  also within the predetermined expiration time  260 . The active sub-client sends an acknowledgement  266 . The predetermined expiration time  260  corresponds to the regularly scheduled MAP and thus allows the active WiMAX sub-client  254  to avoid deregistration through interference from other sub-client operations. 
     To further ensure that the WiMAX sub-client will send or receive during the regularly scheduled MAP period without interference, the WiMAX sub-client may pass an offset value to the Bluetooth sub-client to offset Bluetooth transmit/receive processes. Alternately, the Bluetooth sub-client may send a Bluetooth transmission/reception schedule to the WiMAX sub-client during a prescheduled time interval. The coexistence control module may rearrange transmissions of the WiMAX sub-client to minimize Bluetooth WiMAX interference. 
     When both WLAN and WiMAX sub-client modules are active at the same time, the coexistence control module  31  checks that interference between WiMAX and WLAN sub-client modules is minimized. This includes checking that the WLAN sub-client module is associated with a particular AP and restricting the WLAN sub-client module transmissions to a portion of a WiMAX uplink period. Both WLAN and WiMAX sub-client modules may also fragment transmitted units of data or lower power output to ensure minimal interference. Also, one of the WLAN, WiMAX, and Bluetooth sub-clients may selectively reduce signal power to decrease signal interference with signals from another one of the sub-client modules. 
     Important to note is that alternate embodiments of the present disclosure do not require the WLAN sub-client to wake up to service the Bluetooth sub-client. Further, the coexistence control module  31  may run constantly to track or detect which sub-client(s) is in sleep mode and which sub-client(s) is in active mode. Based on this coexistence control module  31 , sharing of common resources may simply be achieved between the sub-client that requests the resource and the active sub-client. 
     Referring now to  FIG. 7 , a method  300  for managing coexistence of multiple sub-client modules is illustrated. In step  302 , the low power (inactive) sub-client module requests components from the active sub-client module. In step  304 , the active sub-client module selectively transitions to a sleep state or pattern and/or reserves a channel for a fixed amount of time with the coexistence control module. The active sub-client module then sends indication back to the low power sub-client module that the components are available. In step  306 , the low power sub-client module transmits/receives with or through the components; and in step  308 , within a predetermined time duration, the low power sub-client module hands back components to the active sub-client module. The active sub-client module and/or the low power sub-client module may be one of WiMAX, WLAN, or Bluetooth. 
     Prior to or during the sleep state of an active WiMAX sub-client module, busy pattern is transmitted to the WiMAX base station. A base station scheduler (not shown) may use the busy pattern to schedule transmissions (uplink and downlink) to and from the active WiMAX sub-client module. The busy pattern may include: Start frame, Offset, Interval, Busy duration, and Busy because of Bluetooth or WLAN. This pattern generally indicates a Bluetooth sub-client module or WLAN sub-client module is using the shared components. 
     When one sub-client module is expecting a downlink transmission, the sub-client module may set a carrier detect signal in the other sub-client module, thereby preventing the other sub-client module from transmitting and causing the other sub-client module to enter a random back-off state. Low power sub-client modules may also hold an “Abort Transmit” signal in the active sub-client module to check that the active sub-client module aborts transmission when the low power sub-client modules are receiving beacons, etc. 
     The WLAN sub-client module may detect a WiMAX signal either through a repeated MAP transmission or through an indication from the WiMAX sub-client module and inform the WLAN AP that it is experiencing interference in the channel and that the AP should switch to a new channel. Repeated MAP transmissions may be detected based on frame duration for WiMAX, which is typically 5 ms. The uplink and/or downlink duty cycle could be ⅔ or ½ of the frame duration. Based on the frame duration interference pattern, the WLAN base station or access point can detect the presence of a WiMAX system. Also the WLAN sub-client or the co-existence control module could implement a preamble detector to detect the transmission of WiMAX. 
     If the AP does not switch to a new channel, the WLAN sub-client module scans for APs on different channels. The channel selection may be based on measured signal-to-noise ratio (SNR) during WiMAX interference, which is a periodic interference. The channel selection may also be based on some average signal-to-noise ratio over a greater time duration than the WiMAX time frame duration. 
     Referring now to  FIG. 8 , a handoff method  350  is illustrated where the sub-client module (e.g. WLAN sub-client module) after reaching a low signal quality threshold with the network, initiates handoff transmissions to the other sub-client module (e.g. WiMAX sub-client module). For seamless handoff, no units of data (e.g. voice-over Internet protocol (VoIP), streaming video, or video conferencing units of data) should be dropped. 
     Referring now to  FIG. 9  in view of  FIG. 8 , a portion of a WiMAX operation time frame is illustrated. In step  352 , when transmit/receive signal quality drops below a disconnect (i.e., link lost) threshold for the WLAN sub-client module, the WLAN sub-client module sends a trigger  353  to the network (or an AP communicating with a WiMAX network). The trigger  353  is sent to a WIMAX base station to indicate that the WLAN sub-client module is initiating a handoff to the WiMAX sub-client module (i.e. that a WiMAX client wants to enter the network.). In step  354 , after the WLAN sub-client module receives a confirmation from the network (or the AP), the WLAN sub-client module begins the handoff to the WiMAX sub-client module. 
     In step  356 , the radio frequency subsystem switches from WLAN frequency to a WiMAX frequency. In step  374 , the WiMAX sub-client module initiates a scan  359  for available WiMAX base stations within selectively determined sleep pattern openings  361 . The openings  361  may be dedicated by the WLAN sub-client module through an Unsolicited Automatic Power Save Delivery (U-APSD) protocol. 
     Referring now to  FIG. 10 , a U-APSD protocol  362  is illustrated for a WLAN sub-client module to transmit voice signals at low power. A WLAN sub-client module quality of service enhanced station (QSTA) (not shown) sends quality of service (QoS) signal data  367  to an AP. The AP acknowledges the signal (i.e., sends an ACK  369 ) and sends VoIP data  371  to the QSTA. The WLAN wakes up after a predetermined time (e.g., 20 ms) and sends another QoS data signal  373 , etc. 
     Referring again to  FIGS. 8 and 9 , step  374  may include scanning for a single base station or all available base stations. In step  376 , the WiMAX sub-client module or the mobility manager module checks that received base station information matches desired base station information. For a negative response, step  374  is repeated. Otherwise, in step  378 , the WiMAX sub-client module starts a network entry procedure  379 . During network entry, the WiMAX sub-client module receives a downlink MAP for receiving data and an uplink MAP for transmitting data. The sleep pattern openings  361  are not synchronous to the downlink MAP or uplink MAP reception. The WLAN sub-client module therefore modifies the sleep openings accordingly. 
     When the uplink MAP indicates a transmit opportunity for the WiMAX sub-client module, and the WLAN station is transmitting units of data during a sleep pattern opening, the sleep pattern opening transmission  365  may be skipped. WiMAX transmissions may also be skipped during important WLAN operations for later retransmission. In step  380 , after completing network entry, the WiMAX sub-client module carries downlink and uplink traffic. The WiMAX sub-client module may therefore remain synchronized with a base station while a WLAN sub-client module is receiving and transmitting data. 
     Referring now to  FIGS. 11A-11D , various exemplary implementations of the present disclosure are shown. Referring now to  FIG. 11A , the present disclosure may implement and/or be implemented in a wireless module  448  of a vehicle  430 . A powertrain control system  432  receives inputs from one or more sensors such as temperature sensors, pressure sensors, rotational sensors, airflow sensors and/or any other suitable sensors and/or that generates one or more output control signals such as engine operating parameters, transmission operating parameters, and/or other control signals. 
     The present disclosure may also be implemented in other control systems  440  of the vehicle  430 . The control system  440  may likewise receive signals from input sensors  442  and/or output control signals to one or more output clients  444 . In some implementations, the control system  440  may be part of an anti-lock braking system (ABS), a navigation system, a telematics system, a vehicle telematics system, a lane departure system, an adaptive cruise control system, a vehicle entertainment system such as a stereo, DVD, compact disc and the like. Still other implementations are contemplated. 
     The powertrain control system  432  may communicate with mass data storage  446  that stores data in a nonvolatile manner. The mass data storage  446  may include optical and/or magnetic storage clients for example hard disk drives HDD and/or DVDs. The HDD may be a mini HDD that includes one or more platters having a diameter that is smaller than approximately 1.8″. The powertrain control system  432  may be connected to memory  447  such as RAM, ROM, low latency nonvolatile memory such as flash memory and/or other suitable electronic data storage. The powertrain control system  432  also may support connections with a wireless system via wireless module  448 . Vehicle  430  may also include a power supply  433 . 
     Referring now to  FIG. 11B , the present disclosure can be implemented in a cellular phone  450  that may include a cellular antenna  451 . The present disclosure may implement and/or be implemented in a wireless module  468 . In some implementations, the cellular phone  450  includes a microphone  456 , an audio output  458  such as a speaker and/or audio output jack, a display  460  and/or an input client  462  such as a keypad, pointing client, voice actuation and/or other input client. The signal processing and/or control circuits  452  and/or other circuits (not shown) in the cellular phone  450  may process data, perform coding and/or encryption, perform calculations, format data and/or perform other cellular phone functions. 
     The cellular phone  450  may communicate with mass data storage  464  that stores data in a nonvolatile manner such as optical and/or magnetic storage clients for example hard disk drives HDD and/or DVDs. The HDD may be a mini HDD that includes one or more platters having a diameter that is smaller than approximately 1.8″. The cellular phone  450  may be connected to memory  466  such as RAM, ROM, low latency nonvolatile memory such as flash memory and/or other suitable electronic data storage. The cellular phone  450  also may support connections with a wireless system via wireless module  468 . Cellular phone  450  may also include a power supply  453 . 
     Referring now to  FIG. 11C , the present disclosure can be implemented in a set top box  480 . The present disclosure may implement and/or be implemented in a wireless module  496 . The set top box  480  receives signals from a source such as a broadband source and outputs standard and/or high definition audio/video signals suitable for a display  488  such as a television and/or monitor and/or other video and/or audio output clients. The signal processing and/or control circuits  484  and/or other circuits (not shown) of the set top box  480  may process data, perform coding and/or encryption, perform calculations, format data and/or perform any other set top box function. 
     The set top box  480  may communicate with mass data storage  490  that stores data in a nonvolatile manner. The mass data storage  490  may include optical and/or magnetic storage clients for example hard disk drives HDD and/or DVDs. The HDD may be a mini HDD that includes one or more platters having a diameter that is smaller than approximately 1.8″. The set top box  480  may be connected to memory  494  such as RAM, ROM, low latency nonvolatile memory such as flash memory and/or other suitable electronic data storage. The set top box  480  also may support connections with a wireless system via wireless module  496 . Set top box  480  may also include a power supply  483 . 
     Referring now to  FIG. 11D , the present disclosure can be implemented in a media player  500 . The present disclosure may implement and/or be implemented in a wireless module  516 . In some implementations, the media player  500  includes a display  507  and/or a user input  508  such as a keypad, touchpad and the like. In some implementations, the media player  500  may employ a graphical user interface (GUI) that typically employs menus, drop down menus, icons and/or a point-and-click interface via the display  507  and/or user input  508 . The media player  500  further includes an audio output  509  such as a speaker and/or audio output jack. The signal processing and/or control circuits  504  and/or other circuits (not shown) of the media player  500  may process data, perform coding and/or encryption, perform calculations, format data and/or perform any other media player function. 
     The media player  500  may communicate with mass data storage  510  that stores data such as compressed audio and/or video content in a nonvolatile manner. In some implementations, the compressed audio files include files that are compliant with MP3 format or other suitable compressed audio and/or video formats. The mass data storage may include optical and/or magnetic storage clients for example hard disk drives HDD and/or DVDs. The HDD may be a mini HDD that includes one or more platters having a diameter that is smaller than approximately 1.8″. The media player  500  may be connected to memory  514  such as RAM, ROM, low latency nonvolatile memory such as flash memory and/or other suitable electronic data storage. The media player  500  also may support connections with a wireless system via wireless module  516 . Media player  500  may also include a power supply  513 . Still other implementations in addition to those described above are contemplated. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, while this disclosure has been described in connection with particular examples thereof, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.