Patent Publication Number: US-11659411-B2

Title: Single radio switching between multiple wireless links

Description:
RELATED APPLICATIONS 
     This application is a continuation from U.S. application Ser. No. 15/149,111, filed May 7, 2016, which is related to U.S. patent application Ser. No. 15/149,109, entitled “SINGLE RADIO SERVING MULTIPLE WIRELESS LINKS”, filed on May 7, 2016, the contents of which are incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Wireless communication may be used as a means of accessing a network. Wireless communication has certain advantages over wired communications for accessing a network. One of those advantages is a lower cost of infrastructure to provide access to many separate locations or addresses compared to wired communications. This is the so-called “last mile” or “last meter” problem. Another advantage is mobility. Wireless communication devices, such as cell phones, printers, and accessories (e.g., keyboards, mice, remote controls, video game controller) are not tied by wires to a fixed location. 
     To facilitate wireless communications, various organizations and industry groups have promulgated a number of wireless standards. These include the IEEE 802.11 (Wi-Fi) standards, and Wi-Fi Direct (WFD). All of these standards may include specifications for various aspects of wireless communication with a network. These aspects include processes for registering on the network, carrier modulation, frequency bands of operation, and message formats. 
     SUMMARY 
     Examples discussed herein relate to configuring a device with a single wireless interface radio to establish and maintain, at the same time, both a high-throughput (e.g., Wi-Fi) connection and a low-latency (i.e., latency optimized) connection. A wireless interface radio is configured to communicate with an access node (e.g., Wi-Fi router) using a first frequency band and a first series of time allocations. The wireless interface radio is also configured to communicate with at least one client device (e.g., game controller) using a second frequency band and a second series of time allocations. The first series of time allocations and the second series of time allocations are non-overlapping. Thus, the communication by the wireless interface radio is both frequency division multiplexed (FDM) and time division multiplexed (TDM). Information is sent to at least one client device via the second frequency band. This information is to be used by at least one client device to select a time to transmit using the second frequency band. Based on a transmission received via the wireless interface radio, a first duration of a first time allocation of at least one of the first series of time allocations and the second series of time allocations is altered. This allows the wireless interface radio to extend (or shorten) the period it is listening on a particular frequency band in order to allow the transmission to complete. 
     In an example, a high-throughput link is configured that uses a wireless interface radio to communicate with an access node using a first frequency band and a first series of time allocations. A low-latency link is also configured that uses the wireless interface radio to communicate with at least one client device using a second frequency band and a second series of time allocations. Since the first series of time allocations and the second series of time allocations are non-overlapping, the two links are a combination of time and frequency multiplexed. A time indicator is sent to a client device that is communicating via the second frequency band. Responsive to this time indicator, the client device selects a time to transmit that is during a one of the second series of time allocations. 
     In an example, a low-latency link between a client device and a soft access point is configured. This low-latency link uses a first frequency band and a first series of time allocations. The access point communicates with a wireless network access node (e.g., wireless router connected to the Internet) using a second frequency band and a second series of time allocations. The first series of time allocations and the second series of time allocations are non-overlapping. A time indicator is received from the access point via the low-latency link. Responsive to this time indicator, the client device is configured to select a transmit time that is during a one of the first series of time allocations. 
     In an example, a first wireless interface link to communicate with an access node using a first channel of a frequency band is established. A second wireless interface link to communicate with a client device using a second channel of the frequency band is also established. Via the first wireless interface link, a first message to the access node indicating the first wireless interface link is to enter a first dormant state is sent. Data is concurrently received from the access node using the first channel and the client device using the second channel by demodulating a wide channel comprising the first channel and the second channel. The concurrently received data including an indicator that the access node has received the first message indicating the first wireless interface link is to enter the first dormant state. 
     In an example, a low-latency link between the client device and a soft access point device is configured. The low-latency link is configured to use a first frequency band and a first series of time allocations. The soft access point device is to communicate with a network access node using a second frequency band and a second series of time allocations. The first series of time allocations and the second series of time allocations are to be non-overlapping. Via the low-latency link, a first message is transmitted to the soft access point using the first frequency band during a first one of the first series of time allocations. In response to not receiving, via the first frequency band, a first acknowledgement associated with the first message, a first retry of the first message is sent to the soft access point using the second frequency band during the first one of the first series of time allocations. In response to receiving, via the second frequency band, a second acknowledgment associated with the first retry of the first message, a second message is sent to the soft access point using the second frequency band during the first one the first series of time allocations. 
     In an example, a wireless interface radio is configured to communicate with a first access node using a first frequency band and a first series of time allocations. The wireless interface radio is also configured to communicate with at least one client device using a second frequency band and a second series of time allocations. The first series of time allocations and the second series of time allocations are non-overlapping. With the access node, a first wireless communication link associated with first media access control (MAC) identifier is established. With the access node, a second wireless communication link associated with a second MAC identifier is established. Information associated with the second MAC identifier is transmitted to constrain a timing that the access node will use for at least one transmission by the access node. 
     In an example, a wireless interface radio is configured to communicate with a first access node using a first frequency band and a first series of time allocations. The wireless interface radio is also configured to communicate with at least one client device using a second frequency band and a second series of time allocations. The first series of time allocations and the second series of time allocations are non-overlapping. A first wireless communication link associated with first media access control (MAC) identifier is established with the access node. Information associated with a second MAC identifier is transmitted to constrain a timing that the access node will schedule at least one transmission by the access node. The second MAC identifier is not associated with a wireless communication link with the access node. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the manner in which the above-recited and other advantages and features can be obtained, a more particular description is set forth and will be rendered by reference to specific examples thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical examples and are not therefore to be considered to be limiting of its scope, implementations will be described and explained with additional specificity and detail through the use of the accompanying drawings. 
         FIG.  1    is a block diagram illustrating a communication system. 
         FIG.  2    is a flowchart illustrating a method of operating a communication system. 
         FIG.  3    is a diagram illustrating dynamic FDM-TDM channel switching. 
         FIG.  4 A  is a diagram illustrating an extended stay on a high-throughput channel. 
         FIG.  4 B  is a diagram illustrating an extended stay on a low-latency channel. 
         FIG.  5    is a flowchart illustrating a method of scheduling a transmission by a client device. 
         FIG.  6    is a diagram illustrating a scheduled transmission. 
         FIG.  7    is a block diagram illustrating a multi-channel single radio Wi-Fi communication system. 
         FIG.  8    is a flowchart illustrating a method for setting a transmission time by a client device. 
         FIG.  9    is a diagram illustrating multi-channel reception by a single radio. 
         FIG.  10    is a diagram illustrating multi-channel reception to prevent holdover. 
         FIG.  11    is a diagram illustrating multi-channel transmission. 
         FIG.  12    is a diagram illustrating client device following. 
         FIG.  13    is a diagram that illustrates setting an access node transmission time. 
         FIG.  14    is a diagram that illustrates setting a broadcast/multicast transmission time. 
         FIG.  15    is a diagram illustrating time allocations to receive beacon transmissions. 
         FIG.  16    is a diagram illustrating an aggregated frame transmission. 
         FIG.  17    is a flowchart illustrating a method of operating a communication system. 
         FIG.  18    is a flowchart illustrating a method of operating a client device. 
         FIG.  19    is a flowchart illustrating a method of using a connected virtual client to constrain access point transmission timing. 
         FIG.  20    is a flowchart illustrating a method of using a non-connected virtual client to constrain access point transmission timing. 
         FIG.  21    is a block diagram of an example device with wireless capability. 
         FIG.  22    is a block diagram of an example computer system. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Examples are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the subject matter of this disclosure. The implementations may include a machine-implemented method, a computing device, a state-machine implemented method, or wireless network device. 
     In an embodiment, a computing device (such as a computer gaming console, tablet PC, set-top box, smartphone, wireless enabled television, etc.) uses only a single radio to concurrently communicate with a wireless network access point and wireless client devices. For example, a game console may use a single radio to communicate with a Wi-Fi router and with game controllers. Typically, communication with the Wi-Fi router is desired to have high-throughput while communication with the game controllers is desired to have low-latency. 
     To establish and maintain both a high-throughput link with the Wi-Fi access point, and a low-latency link with the wireless game controller(s), the single Wi-Fi radio of the computing device is configured to periodically switch between a channel used for the high-throughput link and a different channel that is used for the low-latency link—thus implementing a combination of frequency division multiplexing (FDM) and time division multiplexing (TDM). However, because (at least) the access point used for the high-throughput link is unaware that the computing device is periodically switching channels, the computing device (and/or clients of the computing device&#39;s soft access point) may deviate from strict time-based channel switching in order to maintain reliable communication. In addition, the computing device may use aspects of the Wi-Fi protocol standard to ensure that periodically switching its single radio between the two channels is accomplished while maintaining reliable communication on both channels. 
     For example, one issue that can occur is when the wireless network access point for the high-throughput link is sending (and computing device is receiving) a beacon frame when the time for a channel switchover occurs. If the channel switchover were to occur on schedule, at least part of the information in the beacon frame would be missed. In an embodiment, the computing device postpones switching between channels in order to complete the reception of the beacon frame. The computing device may then shorten the time spent on the low-latency channel during a subsequent period that is allocated to the low-latency channel. This adjustment can be used to maintain an average period for cycling between channels, and/or maintain a sleep/wake schedule synchronization with client devices on the low-latency link. 
     In another example, a client device starts to transmit on the low-latency link a short time before a channel switchover is to occur. Again, if the channel switchover were to occur on schedule, at least part of the information being transmitted by the client device would be missed. In an embodiment, if a transmission by a client device is detected close to the channel switching time, the computing device can postpone switching between channels in order to completely receive the transmission from the client device. The computing device may then shorten the time spent on the high-throughput channel during a subsequent period allocated to the high-throughput channel. This adjustment can be used to maintain an average period for cycling between channels, and/or maintain a sleep/wake schedule synchronization with client devices on the low-latency link. 
     In another example, the relative time spent on the high-throughput channel versus the low-latency channel may be varied according to the traffic on one or both of the channels. In this manner, throughput on the high-throughput channel and latency on the low-latency channel can be optimized according to the activity on the channels. 
     In another example, the computing device can send scheduling and/or control information to its client devices via the low-latency links. This information can be used to prevent, or help prevent, attempts by the client devices on the low-latency link from trying to transmit while the computing device is configured to listen to only the high-throughput channel. For example, the computing device may send a recommended sleep duration to a client device. This sleep duration can be selected such that the client device will (or is likely to) remain asleep while the computing device is configured to listen to the high-throughput channel. 
     In another example, to prevent transmissions by the wireless network access point to the computing device via the high-throughput channel while the computing device is operating on the low-latency channel, the computing device can indicate (e.g., in a NULL frame on the high-throughput channel) to the wireless network access point that it is going to sleep. If, for some reason, the wireless network access point does not respond to this message (e.g., with an ACK frame), the computing device may switch into a mode whereby the computing device can monitor the high-throughput channel for an acknowledgement while simultaneously listening for traffic from client devices on the low-latency channel. 
     In another example, if the wireless network access point has not acknowledged that the computing device is going to sleep, and the computing device wants to transmit on the low-latency link (as opposed to just listening), the computing device can send a transmission on the high-throughput channel that appears to be from a device that is not connected to the wireless network access point. This transmission can indicate a transmission duration that corresponds to the time the computing device needs to transmit on the low-latency link. In this manner, the Wi-Fi inter-network/intra-channel collision avoidance algorithm used by the wireless network access point will prevent the wireless network access point from transmitting to the computing device (or any other Wi-Fi device.) After the computing device has completed its transmission on the low-latency link, the computing device can switch into the aforementioned mode whereby the computing device can monitor the high-throughput channel for an acknowledgement while simultaneously listening for traffic on the low-latency channel. 
     In another example, when it is time for the computing device to switch its single radio from the high-throughput channel to the low-latency channel (i.e., an FDM-TDM channel switch), the wireless network access node may be sending a beacon frame. Likewise, relatively close to the start of a beacon frame transmission, the computing device may have sent an indicator (e.g., in a NULL frame on the high-throughput channel) to the wireless network access point that the computing device is going to sleep. However, because the wireless network access point is sending, or about to send, a beacon frame, the wireless network access point defers sending an acknowledgement that the computing device is going to sleep. To prevent these cases from occurring, the computing device can adjust the time allocations spent on the high-throughput channel such that the beacon frame transmissions occur while the computing device is operating on the high-throughput channel. 
     In another example, when it is time for the computing device to switch its single radio from the high-throughput channel to the low-latency channel (i.e., an FDM-TDM channel switch), the wireless network access node may be sending broadcast or multicast frames. Since the wireless network access node is busy sending these frames, the computing device may not be able to send an indicator to the wireless network access point that it is going to sleep and/or receive an acknowledgement. To prevent this from occurring, the computing device can send transmissions on the high-throughput channel that appears to be from a device that is connected to the wireless network access point, but that is not identified (e.g., by MAC address) as being the computing device (i.e., a ‘virtual’ client). These transmissions indicate to the wireless network access point that the virtual client device will be sleeping at all times except those close to the beacon time. Since broadcast/multicast frames are sent at times when all of the clients are awake, the wireless network access point will be constrained to schedule broadcast/multicast frames close to the beacon time when the virtual client device appears to wireless network access node to be awake. 
     In another example, when it is time for the computing device to switch its single radio from the high-throughput channel to the low-latency channel (i.e., for a FDM-TDM channel switch), the wireless network access node may be sending aggregated frames to another client (i.e., not the computing device). Since the wireless network access node is busy sending these frames, the computing device may not be able to send an indicator to the wireless network access point that the computing device is going to sleep and/or receive an acknowledgement. When this occurs, the computing device may elect to continue to switch channels according to the FDM-TDM time allocations without informing the wireless network access point that the computing device is going to sleep. By continuing to switch without informing the wireless network access node, the computing device may switch away and then back to the high-throughput channel before the aggregated frame transmission completes. By returning to the high-throughput channel before the frame transmission completes, it is unlikely that the computing device will miss a transmission from the wireless network access point, or disconnect the link with the computing device. 
       FIG.  1    is a block diagram illustrating a communication system. In  FIG.  1   , communication system  100  comprises wireless network access node  110 , network  120 , client device  130 , and computing device  150 . Computing device  150  includes radio  151 . Wireless network access node  110  is operatively coupled to network  120 . Wireless network access node  110  is operatively coupled to computing device  150  by wireless link  141 . Client device  130  is operatively coupled to computing device  150  by wireless link  142 . 
     Wireless network access node  110  is a network element capable of providing wireless communication to wireless capable devices (e.g., computing device  150 .) Wireless network access node  110  can be, for example, one or more of a Wi-Fi access node, a Wi-Fi hotspot, a Wi-Fi gateway, a base transceiver station, a radio base station, an eNodeB device, or an enhanced eNodeB device. Wireless network access node  110  is connected to network  120 . Example devices that may be, comprise, and/or include wireless network access node  110  include, but are not limited to, example wireless capable device  2100  (described herein with reference to  FIG.  21   ) and/or example computer system  2200  (described herein with reference to  FIG.  22   ). 
     Network  120  is a wide area communication network that can provide wired and/or wireless communication to wireless network access node  110 . Network  120  and can comprise wired and/or wireless communication networks that include processing nodes, routers, gateways, physical and/or wireless data links for carrying data among various network elements, including combinations thereof, and can include a local area network, a wide area network, and an internetwork (including the Internet). Network  120  can also comprise wireless networks, including base station, wireless communication nodes, telephony switches, internet routers, network gateways, computer systems, communication links, or some other type of communication equipment, and combinations thereof. Wired network protocols that may be utilized by network  120  comprise Ethernet, Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier Sense Multiple Access with Collision Avoidance), Token Ring, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM). Links between elements of network  120 , can be, for example, twisted pair cable, coaxial cable or fiber optic cable, or combinations thereof. Wireless network protocols that may be utilized by communication system  100  may comprise one or more IEEE 802 specified protocols. 
     Other network elements may be present in network  120  to facilitate communication with wireless network access node  110  but are omitted for clarity, such as base stations, base station controllers, gateways, mobile switching centers, dispatch application processors, and location registers such as a home location register or visitor location register. Furthermore, other network elements may be present to facilitate communication between among elements of communication system  100  which are omitted for clarity, including additional computing devices, client devices, access nodes, routers, gateways, and physical and/or wireless data links for carrying data among the various network elements. 
     In an embodiment, computing device  150  may be any device, system, combination of devices, or other such communication platform capable of communicating wirelessly with wireless network access node  110  and wirelessly with client device  130 . Computing device  150  can operate using a single wireless interface radio  151  to establish wireless links  141  and  142  and communicate concurrently with wireless network access node  110  and client device  130 , respectively. Computing device  150  may connect to wireless network access node  110  as a client of a wireless network (e.g., a wireless network associated with a single BSSID) provided by wireless network access node  110 . Client device  130  may connect to a wireless network provided by computing device  150 . The wireless network provided by computing device  150  may be a peer-to-peer type wireless network. Computing device  150  may be known as the ‘soft access point’ or ‘soft-AP’ for the network computing device  150  provides to client device  130  via wireless link  142 . Example devices that may be, comprise, and/or include computing device  150  include, but are not limited to, example wireless capable device  2100  (described herein with reference to  FIG.  21   ) and/or example computer system  2200  (described herein with reference to  FIG.  22   ). 
     Client device  130  may be, for example, a video game controller, computer peripheral (e.g., mouse, keyboard, printer, speakers), a mobile phone, a wireless phone, a wireless modem, a personal digital assistant (PDA), a voice over internet protocol (VoIP) phone, a voice over packet (VOP) phone, or a soft phone, as well as other types of devices or systems that can exchange data with computing device  150  via wireless link  142 . Other types of communication platforms are possible. Example devices that may be, comprise, and/or include client device  130  include, but are not limited to, example wireless capable device  2100  (described herein with reference to  FIG.  21   ) and/or example computer system  2200  (described herein with reference to  FIG.  22   ). 
     In an embodiment, computing device  150  controls and/or configures radio  151  to implement a combination of frequency division multiplexing (FDM) and time division multiplexing (TDM) for the communication via wireless link  141  and wireless link  142 . In other words, radio  151  both switches between at least two frequency bands (i.e., channels) to implement frequency division multiplexing, and also communicates on a respective frequency band during a respective series of non-overlapping time allocations to implement time division multiplexing. Thus, radio  151  may periodically communicate with wireless network access node  110  during selected time periods using a first channel, and communicate with client device  130  using wireless link  142  using a second channel during the rest of the time. In an embodiment, the time periods are selected such that wireless link  141  is configured as a high-throughput link and wireless link  142  is configured as a low-latency link. In another embodiment, the time periods are selected such that wireless link  142  is configured as a high-throughput link and wireless link  141  is configured as a low-latency link. 
     Wireless network access node  110  may be unaware that computing device  150  is using FDM-TDM channel switching to communicate via wireless links  141  and  142  using a single radio  151 . Accordingly, wireless network access node  110  may function under an assumption that wireless link  141  is always on the same channel and is conforming to the protocol associated with the wireless network type being provided by wireless network access node  110 . 
     In an embodiment, computing device  150  may control radio  151  to deviate from strict fixed time channel switching in order to maintain reliable communication with both client device  130  and/or wireless network access node  110 . In typical operation, computing device  150  communicates alternately with wireless network access node  110  via link  141  and with client device  130  via link  142 . When communicating with wireless network access node  110 , radio  151  uses a first channel. When communicating with client device  130 , radio  151  uses a second channel. At nominally fixed intervals (i.e., TDM), radio  151  is switched between the first channel and the second channel (i.e., FDM) 
     Wireless network access node  110  may be sending (or will be unable to complete) a beacon frame when a time for FDM-TDM channel switch from link  141  to link  142  occurs. If the switchover of radio  151  from link  141  to link  142  were to occur at that predetermined time, at least part of the information in the beacon frame would be missed by computing device  150 . In an embodiment, computing device  150  does not switch between channels at the predetermined time and instead delays the switch in order to complete the reception of the beacon frame from wireless network access node  110 . Computing device  150  may delay the FDM-TDM channel switch by a predetermined amount of time (e.g., several of milliseconds) that allows for the complete reception of any beacon frame which would not complete before the time nominally scheduled for the FDM-TDM channel switch. 
     After a FDM-TDM channel switch from link  141  to  142  is delayed to allow reception of the beacon frame to complete, computing device  150  may then shorten the next (or any subsequent) time spent on link  141 . This adjustment can be used to maintain an average (or nominal) period for cycling between links  141  and  142 . This adjustment can also be used to help maintain a sleep/wake schedule synchronization with client device  130  and link  142 . 
     Client device  130  may be sending (or will be unable to complete) a transmission when a time for a FDM-TDM channel switch from link  142  to link  141  occurs. If the switchover of radio  151  from link  142  to link  141  were to occur at that predetermined time, at least part of the information transmitted by client device  130  could be missed by computing device  150 . In an embodiment, computing device  150  does not switch between channels at the predetermined time and instead delays the switch in order to complete the reception of the transmission from client device  130 . Computing device  150  may delay the FDM-TDM channel switch by a predetermined amount of time (e.g., several of milliseconds) that allows for the complete reception of any client device  130  transmission which would not complete before the time nominally scheduled for the FDM-TDM channel switch. 
     After a FDM-TDM channel switch from link  142  to  141  is delayed to allow reception of the beacon frame to complete, computing device  150  may then shorten the next (or any subsequent) time spent on link  141 . This adjustment can be used to maintain an average (or nominal) period for cycling between links  141  and  142 . This adjustment can also be used to help maintain a sleep/wake schedule synchronization with client device  130  and link  142 . 
     In an embodiment, the relative time spent communicating via link  141  versus the time spent communicating via link  141  can be varied by computing device  150  according to the traffic on one or both of the channels. In another embodiment, the relative time spent communicating via link  141  versus the time spent communicating via link  141  be can varied by computing device  150  based on one or more of: an application being run on computing device  150 , a device classification of client device  130  (e.g., mouse vs. keyboard vs. game controller, etc.) In this manner, throughput on link  141  and latency on link  142  can be optimized according to the activity on the channels and/or expected needs of an applications and/or client device. Likewise, throughput on link  142  and latency on link  141  can be optimized according to the activity on the channels and/or expected needs of an applications and/or client device. 
     In an embodiment, computing device  150  sends scheduling and/or control information to client device  130  via link  142 . This information can be used to prevent, or help prevent, attempts by client device  130  to transmit while radio  151  is configured to listen to only link  141 . For example, computing device  150  may send a recommended sleep duration to client device  130 . This sleep duration can be selected by computing device  150  such that client device  130  will (or is likely to) remain asleep during period(s) of time when radio  151  is configured to listen on link  141 . 
     As described herein, computing device  150  regularly spends at least some time with radio  151  configured to communicate via link  142 . When radio  151  is configured to communicate via link  142 , it cannot communicate via link  141 . In an embodiment, before performing a FDM-TDM channel switch from link  141  to link  142 , computing device  150  sends an indicator to wireless network access node  110 . This indicator informs wireless network access node  110  that, as far as link  141  is concerned, computing device  150  is going to sleep and will not be receiving communication via link  141 . Wireless network access node  110  confirms receipt of this indicator by sending computing device  150  an acknowledgement message via link  141 . When computing device  150  receives the acknowledgement message via link  141 , computing device  150  may perform a FDM-TDM channel switch to link  142  (or go to sleep.) 
     Wireless network access node  110  may not respond to the ‘going to sleep’ indicator before the predetermined time for the FDM-TDM channel switch from link  141  to link  142 . This lack of response may occur because wireless network access node  110  is busy with other traffic (e.g., sending a beacon frame) or interference (e.g., traffic on another wireless network operating on the same or nearby channels.) Computing device  150  may then monitor link  141  and link  142  simultaneously. Computing device  150  may monitor link  141  in order to receive the acknowledgement message. Computing device  150  may monitor link  142  in order to receive transmissions from client device  130  and respond to these transmissions with a limited maximum latency time period. Computing device  150  may monitor both link  141  and  142  by receiving and demodulating communication on both the channel used by link  141  and the channel used by link  142 . For example, if both link  141  and  142  use orthogonal frequency division multiplexing (OFDM), Computing device  150  may monitor both link  141  and  142  by receiving at least the OFDM carriers associated with link  141  and link  142 , discarding data corresponding to OFDM carriers not used by links  141  and  142 , and then separately (i.e., by link or channel) processing the data associated with the respective OFDM carriers associated with each link  141  and  142 . In an embodiment, appropriate filters and/or filter banks may be used for performing the desired separation. 
     Computing device  150  may have data to transmit to client device  130  when wireless network access node  110  has not responded to the ‘going to sleep’ indicator before a predetermined time for a FDM-TDM channel switch from link  141  to link  142 . To prevent wireless network access node  110  from transmitting on link  141  while computing device  150  is transmitting data to client device  130  after the channel switch to link  142 , computing device  150  can send a transmission on the same channel as link  141 . This transmission is sent such that the transmission appears to be from a device that is not connected to wireless network access node  110 . This transmission can indicate a transmission duration that corresponds to the time the computing device needs to transmit on link  142 . In this manner, a collision avoidance algorithm used by wireless network access node  110  can prevent the wireless network access node  110  from transmitting via link  142  for the specified transmission duration. After the computing device  150  has completed its transmission on link  142 , computing device  150  can switch into the aforementioned mode whereby computing device  150  can monitor link  141  for an acknowledgement while simultaneously listening for traffic on link  142 . 
     To prevent (or help prevent) cases where wireless network access node  110  is delayed from sending an acknowledgment due to a beacon frame transmission (or impending beacon frame transmission), computing device  150  can adjust the time allocations (and/or timing of the FDM-TDM channel switches) spent on link  141  and link  142  such that the beacon frame transmissions occur while radio  151  is known to be (or very likely to be) configured to be on link  141 . 
     Broadcast or multicast frames being sent by wireless network access node  110  may also cause computing device  150  and/or wireless network access node  110  from communicating or responding to a ‘going to sleep’ message. Computing device  150  can send a transmission on the high-throughput channel that appears to be from a device that is connected to the wireless network access node  110 , but where that device is not computing device  150  (i.e., a ‘virtual’ client of wireless network access node  110  created by computing device  150  for this purpose.) This transmission can indicate to wireless network access node  110  that the virtual client device will be sleeping at all times except those close to the beacon time. Since broadcast/multicast frames are sent at times when all of the clients of wireless network access node  110  are awake, wireless network access node  110  will be constrained to schedule broadcast/multicast frames close to the beacon time. This at least limits the effect of broadcast/multicast frames to switchover times that are close to the beacon time. 
     Aggregated frames being sent by wireless network access node  110  may also cause computing device  150  and/or wireless network access node  110  from communicating or responding to a ‘going to sleep’ message. Since wireless network access node  110  is busy sending these aggregated frames, computing device  150  may not be able to send the ‘going to sleep’ indicator to wireless network access node  110  and/or receive an acknowledgement. When this occurs, computing device  150  may elect to continue to switch between links  141  and  142  according to the FDM-TDM time allocations without informing wireless network access node  110  that it is going to sleep. By continuing to switch without informing wireless network access node  110 , computing device  150  may switch away from link  141  to link  142  and then back to link  141  before the aggregated frame transmission completes. By returning to link  141  before the frame transmission completes, computing device  150  may not miss a transmission from wireless network access node  110 , or need to re-establish link  141 . 
       FIG.  2    is a flowchart illustrating a method of operating a communication system. The steps illustrated in  FIG.  2    may be performed by one or more elements of communication system  100 . A wireless interface radio is configured to communicate with an access node using a first frequency band and a first series of time allocations ( 202 ). For example, radio  151  may be periodically (and repetitively) configured and reconfigured by computing device  150  to communicate with wireless network access node  110  using a first wireless channel (i.e., frequency band—such as Wi-Fi channel 1) and a first series of time allocations (e.g., the first 4 ms of an 8 ms cycle). 
     The wireless interface radio is configured to communicate with at least one client device using a second frequency band and a second series of time allocations ( 204 ). For example, radio  151  may be periodically (and repetitively) configured and reconfigured by computing device  150  to communicate with client device  130  using a second wireless channel (i.e., frequency band—such as Wi-Fi channel 6) and a second series of time allocations (e.g., the second 4 ms of an 8 ms cycle). 
     Via the second frequency band, and to the at least one client device, information to be used by the at least one client device to select a time to transmit using the second frequency band is sent ( 206 ). For example, computing device  150  may send, via the second frequency band and to client device  130 , an indicator of a recommended (or commanded) sleep duration and/or wakeup time. When the recommended time arrives, client device  130  may wakeup and transmit to computing device  150  using link  142 . Computing device  150  may select the indicator of a recommended (or commanded) sleep duration and/or wakeup time such that radio  151  will be tuned to the second frequency band when client device  130  wakes up. 
     Based on a transmission received via the wireless interface radio, a first duration of a first time allocation of at least of the first series of time allocations and the second series of time allocations is altered ( 208 ). For example, based on a transmission on link  142  from client device  130 , computing device  150  may delay (i.e., postpone) the FDM-TDM channel switching of channels from a predetermined time to a later time. The amount of delay/postponement may be a predetermined duration. 
     In a particular example, when computing device  150  determines that a transmission on link  142  from client device  130  is unlikely to, or will not, complete before the predetermined time for the FDM-TDM channel switch, computing device  150  may extend the time radio  151  listens to link  142  this cycle. Likewise, when computing device  150  determines that a transmission (e.g., regular traffic, beacon frame, multicast frame, and/or aggregated frame) on link  141  from wireless network access node  110  is unlikely to, or will not, complete before the predetermined time, computing device  150  may extend the time radio  151  listens to link  142  this cycle. Responsive to extending a stay on one of the frequency bands, computing device  150  may shorten a subsequent (e.g., next) stay on the other frequency band. This second altered time allocation may be shortened by the amount that the first time allocation was lengthened. By extending a first time allocation for one frequency band, and shortening a second time allocation for the other frequency band, the overall cycle time between the two bands can be maintained at a desired average or mean cycle time. This can help keep the transmissions and/or wake-up times of client device  130  synchronized with computing device  150 . 
       FIG.  3    is a diagram illustrating dynamic FDM-TDM channel switching. In  FIG.  3   , the horizontal axis represents time, and the vertical axis represents frequency. A first frequency band, or channel, (f 1 ) is shown above the horizontal axis. A second frequency band (f 2 ) is shown below the horizontal axis. The first frequency band is configured to be a high-throughput link and is therefore denoted HT in  FIG.  3   . This first frequency band can correspond to link  141  between computing device  150  and wireless network access node  110 . In another embodiment, this first frequency band can correspond to link  142  between computing device  150  and client device  130 . The second frequency band is configured to be a low-latency link and is therefore denoted LL in  FIG.  3   . This second frequency band can correspond to link  142  between computing device  150  and client device  130 . In another embodiment, this second frequency band can correspond to link  141  between computing device  150  and wireless network access node  110 . 
     Typical (or nominal) FDM-TDM channel switching cycles are shown by FDM-TDM allocations  310 ,  311 ,  320 , and  321 . FDM-TDM allocations  310  and  311  are illustrated as being on the f 1  frequency band and are of duration t a0 . FDM-TDM allocations  320  and  321  are illustrated as being on the f 2  frequency band and are of duration t b0 . Thus, as can be seen from allocations  310  and  320  in  FIG.  3   , a FDM-TDM cycle is nominally t cyc =t a0 +t b0  in duration. It can also be seen from allocations  310 ,  311 ,  320 , and  321  that the times that allocations  310  and  311  are active on the first frequency band do not overlap the times that allocations  320  and  321  are active on the second frequency band. Thus, allocations  310 ,  311 ,  320 , and  321  effect a multiplexing scheme that implements a combination of non-overlapping FDM and non-overlapping TDM. 
       FIG.  3    also illustrates extended allocation  312  and shortened allocation  322 . Extended allocation  312  and/or shortened allocation  322  may be the result of an extended stay (i.e., postponed FDM-TDM channel switching time) by computing device  150  on the f 1  frequency band. FDM-TDM allocation  312  is illustrated as being on the f 1  frequency band for a duration t a1 =t a0 +t 1 . Dashed line  322  illustrates the nominal switching time (i.e., without allocation  312  being extended and/or allocation  322  being shortened) between allocation  312  and  322 . FDM-TDM allocation  322  is illustrated as being on the f 2  frequency band for a duration t b1 =t b0 −t 1 . Thus, as can be seen from allocations  312  and  322  in  FIG.  3   , the FDM-TDM cycle encompassing allocations  312  and  322  is nominally t cyc =t a0 +t b0  in duration. 
       FIG.  3    also illustrates shortened allocation  313  and extended allocation  323 . Shortened allocation  313  and/or extended allocation  323  may be the result of a shortened stay by computing device  150  on the f 1  frequency band. FDM-TDM allocation  313  is illustrated as being on the f 1  frequency band for a duration t a2 =t a0 −t 2 . Dashed line  333  illustrates the nominal switching time (i.e., without allocation  313  being shortened and/or allocation  323  being lengthened) between allocation  313  and  323 . FDM-TDM allocation  322  is illustrated as being on the f 2  frequency band for a duration t b2 =t b0 +t 2 . Thus, as can be seen from allocations  313  and  323  in  FIG.  3   , the FDM-TDM cycle encompassing allocations  313  and  323  is nominally t cyc =t a0 +t b0  in duration. In an embodiment, t 1  may be a predetermined amount of time. In another embodiment, t 1  may be dynamically adjusted by computing device  150 . The dynamic adjustments made to t 1  may be based on factors such as the type of transmission that caused a postponement to a FDM-TDM channel switching cycle, traffic on the current (or next) channel, an application being run on computing device  150 , a device classification of client device  130  (e.g., mouse vs. keyboard vs. game controller, etc.), or other factors that contribute to the performance (e.g., latency and/or throughput) of communication system  100 , and links  141  and  142 , in particular. 
       FIG.  4 A  is a diagram illustrating an extended stay on a high-throughput channel. In  FIG.  4 A , the horizontal axis represents time, and the vertical axis represents frequency. A first frequency band, or channel (f 1 ) is shown above the horizontal axis. A second frequency band (f 2 ) is shown below the horizontal axis. The first frequency band is configured to be a high-throughput link and is therefore denoted HT in  FIG.  4 A . This first frequency band can correspond to link  141  between computing device  150  and wireless network access node  110 . The second frequency band is configured to be a low-latency link and is therefore denoted LL in  FIG.  4 A . This second frequency band can correspond to link  142  between computing device  150  and client device  130 . 
       FIG.  4 A  illustrates a first FDM-TDM allocation  412  that is on the f 1  frequency band and a second FDM-TDM allocation  422  that is on the f 2  frequency band. Dashed line  432  illustrates the time a nominal FDM-TDM channel switch would occur between allocation  412  and allocation  422 . Transmission (BT)  451  is illustrated on the f 1  frequency band. Transmission  451  begins before the nominal FDM-TDM channel switch would have occurred (as shown by line  432 ), and ends after the nominal FDM-TDM channel switch would have occurred. Accordingly, allocation  412  is illustrated in  FIG.  4 A  as being extended by t 3  in order to entirely encompass the time that transmission  451  is occurring. Thus, the total duration of allocation  412  after being extended is t a3 =t a0 +t 3 . Likewise, allocation  422  is illustrated in  FIG.  4 A  as being shorted by t 3  to a duration of t b3 =t b0 −t 3 . This helps maintain (at least an average) a FDM-TDM cycle time of t cyc =t a3 +t b3 =t a0 +t b0 . In an example, transmission  451  can be a beacon or other type transmission sent by wireless network access node  110  that computing device  150  should not ignore. 
       FIG.  4 B  is a diagram illustrating an extended stay on a low-latency channel. In  FIG.  4 B , the horizontal axis represents time, and the vertical axis represents frequency. A first frequency band, or channel, (f 1 ) is shown above the horizontal axis. A second frequency band (f 2 ) is shown below the horizontal axis. The first frequency band is configured to be a high-throughput link and is therefore denoted HT in  FIG.  4 B . This first frequency band can correspond to link  141  between computing device  150  and wireless network access node  110 . The second frequency band is configured to be a low-latency link and is therefore denoted LL in  FIG.  4 B . This second frequency band can correspond to link  142  between computing device  150  and client device  130 . In an embodiment, link  141  can be configured to be a low-latency link and is therefore correspond to LL in  FIG.  4 B . Likewise, in an embodiment, link  142  can be configured to be a high-throughput link and therefore correspond to HT in  FIGS.  4 A- 4 C . 
       FIG.  4 B  illustrates a first FDM-TDM allocation  423  that is on the f 2  frequency band and a second FDM-TDM allocation  421  that is on the f 1  frequency band. Dashed line  433  illustrates the time a nominal FDM-TDM channel switch would occur between allocation  423  and allocation  421 . Transmission (CT)  452  is illustrated on the f 2  frequency band. Transmission  452  begins before the nominal FDM-TDM channel switch would have occurred (as shown by line  433 ), and ends after the nominal FDM-TDM channel switch would have occurred. Accordingly, allocation  423  is illustrated in  FIG.  4 B  as being extended by t 4  in order to entirely encompass the time that transmission  452  is occurring. Thus, the total duration of allocation  423  after being extended is t b4 =t b0 +t 4 . Likewise, allocation  421  is illustrated in  FIG.  4 B  as being shorted by t 4  to a duration of t a4 =t a0 −t 4 . This helps maintain (at least an average) a FDM-TDM cycle time of t cyc =t a4 +t b4 =t a0 +t b0 . In an example, transmission  452  can be a data transmission sent by client device  130  that computing device  150  should not ignore. 
       FIG.  5    is a flowchart illustrating a method of scheduling a transmission by a client device. The steps illustrated in  FIG.  5    may be performed by one or more elements of communication system  100 . A high-throughput link that uses a wireless interface radio to communicate with an access node using a first frequency band and a first series of time allocations is configured ( 502 ). For example, computing device  150  may configure link  141  as a high-throughput link that is periodically operates on a first frequency band during a first set of allocated time durations. 
     A low-latency link that uses the wireless interface radio to communicate with at least one client device using a second frequency band and a second series of time allocations is configured ( 504 ). For example, computing device  150  may configure link  142  as a low-latency link that is periodically operates on a second frequency band during a second set of allocated time durations. 
     A first time indicator is sent to a first client device that is communicating via the second frequency band. In response to the first time indicator, the client device selects a first time to transmit that is during a one of the second series of time allocations ( 506 ). For example, computing device  150  may send a message to client device  130  instructing client device  130  to ‘wake up’ at a selected time (or, roughly equivalently, is to remain ‘asleep’ for a selected period). In response to this message, client device  130  selects a time to ‘wake up’ and send data or otherwise communicate with computing device  150  via link  142 . 
     The first time indicator may be specified as an absolute time or referenced to, for example, a boundary (beginning or end) of one of the first or second series of time allocations, or a boundary between ones of the first and second series of time allocations. Depending on the time selected by the client device, when the client ‘wakes up’ and transmits, computing device  150  may need to extend or shorten one or more of the first and second series of time allocations as described herein. 
     It should also be understood that, in an embodiment, the configured roles of links  141  and  142  may be swapped. In other words, link  141  may be configured to be a low-latency link and link  142  may be configured to be a high-throughput link. 
       FIG.  6    is a diagram illustrating a scheduled transmission. In  FIG.  6   , the horizontal axis represents time, and the vertical axis represents frequency. A first frequency band, or channel, (f 1 ) is shown above the horizontal axis. A second frequency band (f 2 ) is shown below the horizontal axis. The first frequency band is configured to be a high-throughput link and is therefore denoted HT in  FIG.  6   . This first frequency band can correspond to link  141  between computing device  150  and wireless network access node  110 . The second frequency band is configured to be a low-latency link and is therefore denoted LL in  FIG.  6   . This second frequency band can correspond to link  142  between computing device  150  and client device  130 . In an embodiment, link  141  can be configured to be a low-latency link and is therefore correspond to LL in  FIG.  6   . Likewise, in an embodiment, link  142  can be configured to be a high-throughput link and therefor correspond to HT in  FIG.  6   . 
       FIG.  6    illustrates a first FDM-TDM allocation  621  that is on the f 2  frequency band. Following allocation  621 , a second FDM-TDM allocation  611  that is on the f 1  frequency band is illustrated. Following allocation  611 , a third FDM-TDM allocation  621  that is on the f 2  frequency band is illustrated. A transmission with a time indicator (t w )  653  is illustrated as occurring during time allocation  621 . The time indicator  653  determines when transmission  654  is to occur (e.g., t w  may specify a ‘wake up’ time for client device  130 ). Time indicator  653  is illustrated in  FIG.  6    as being referenced to the boundary between allocation  621  and  611 . 
       FIG.  7    is a block diagram illustrating a multi-channel single radio Wi-Fi communication system. In  FIG.  7   , communication system  700  comprises Wi-Fi access point  710 , network  720 , client device  730 , client device  731 , and computing device  750 . Computing device  750  includes Wi-Fi radio  751 . Wi-Fi access point  710  is operatively coupled to network  720 . Wi-Fi access point  710  is operatively coupled to computing device  750  by wireless link  741 . Client device  730  is operatively coupled to computing device  750  by wireless link  142 . Client device  731  is operatively coupled to computing device  750  by wireless link  143 . 
     Wi-Fi access point  710  is a network element capable of providing wireless communication to wireless devices (e.g., computing device  150 ) according to one or more the Wi-Fi (802.11) standards and its variants. Wi-Fi access point  710  can be, for example, one or more of a Wi-Fi access point (node), a Wi-Fi hotspot, a Wi-Fi gateway, a base transceiver station, a radio base station, an eNodeB device, or an enhanced eNodeB device. Wi-Fi access point  710  is connected to network  720 . Example devices that may be, comprise, and/or include Wi-Fi access point  710  include, but are not limited to, example wireless capable device  2100  (described herein with reference to  FIG.  21   ) and/or example computer system  2200  (described herein with reference to  FIG.  22   ). 
     Network  720  is a wide area communication network that can provide wired and/or wireless communication to Wi-Fi access point  710 . Network  720  and can comprise wired and/or wireless communication networks that include processing nodes, routers, gateways, physical and/or wireless data links for carrying data among various network elements, including combinations thereof, and can include a local area network, a wide area network, and an internetwork (including the Internet). Network  720  can also comprise wireless networks, including base station, wireless communication nodes, telephony switches, internet routers, network gateways, computer systems, communication links, or some other type of communication equipment, and combinations thereof. Wired network protocols that may be utilized by network  720  comprise Ethernet, Fast Ethernet, Gigabit Ethernet, Local Talk (such as Carrier Sense Multiple Access with Collision Avoidance), Token Ring, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM). Links between elements of network  720 , can be, for example, twisted pair cable, coaxial cable or fiber optic cable, or combinations thereof. Wireless network protocols that may be utilized by communication system  700  may comprise one or more IEEE 802 specified protocols, 
     Other network elements may be present in network  720  to facilitate communication with Wi-Fi access point  710  but are omitted for clarity, such as base stations, base station controllers, gateways, mobile switching centers, dispatch application processors, and location registers such as a home location register or visitor location register. Furthermore, other network elements may be present to facilitate communication between among elements of communication system  700  which are omitted for clarity, including additional computing devices, client devices, access nodes, routers, gateways, and physical and/or wireless data links for carrying data among the various network elements. 
     In an embodiment, computing device  750  may be any device, system, combination of devices, or other such communication platform capable of wirelessly communicating, using a single radio  751 , with Wi-Fi access point  710  using a Wi-Fi specified protocol, and wirelessly communicating with client devices  730  and  731  using a latency optimized protocol specified for low latency. In another embodiment, computing device  750  may be any device, system, combination of devices, or other such communication platform capable of wirelessly communicating, using a single radio  751 , with Wi-Fi access point  710  using a Wi-Fi specified protocol, and wirelessly communicating with client devices  730  and  731  using a Wi-Fi Direct specified protocol. Computing device  750  can operate using a single wireless interface radio  751  to establish wireless links  741 ,  742 , and  743  and communicate concurrently with Wi-Fi access point  710  and client devices  730  and  731 , respectively. Computing device  750  may connect to Wi-Fi access point  710  as a client of a Wi-Fi network (e.g., a wireless network associated with a single BSSID) provided by Wi-Fi access point  710  that also connects to network  720 . Client devices  730  and  731  may connect to a wireless network provided by computing device  750 . The wireless network provided by computing device  750  may be a peer-to-peer type wireless network (e.g. a latency optimized client network or a Wi-Fi Direct network.) Computing device  750  may include hardware and/or software that allows computing device  750  to function as what is known as a ‘soft access point’ or ‘soft-AP’ for a latency optimized or a WFD network provided by computing device  750  to client device  730  and client device  731 . 
     Computing device  750  may include hardware and/or software to establish and maintain multiple client connections  755  and  756  to Wi-Fi access point  710  as clients of a Wi-Fi network provided by Wi-Fi access point  710 . Likewise, computing device  750  may include hardware and/or software to establish and maintain a connection or apparent connection to a Wi-Fi access point that is not Wi-Fi access point  710 . Client connection  755  is typically used as the client to carry traffic between Wi-Fi access point  710  and computing device  750 . Client connections  756  and  757  are not typically used to carry traffic, and may thus be referred to as ‘virtual’ clients. Example devices that may be, comprise, and/or include computing device  750  include, but are not limited to, example wireless capable device  2100  (described herein with reference to  FIG.  21   ) and/or example computer system  2200  (described herein with reference to  FIG.  22   ). 
     Client devices  730  and  731  may be, for example, one or more of a video game controller, computer peripheral (e.g., mouse, keyboard, printer, speakers), a mobile phone, a wireless phone, a wireless modem, a personal digital assistant (PDA), a voice over internet protocol (VoIP) phone, a voice over packet (VOP) phone, or a soft phone, as well as other types of devices or systems that can exchange data with computing device  750  via client links  742  and  743 . Other types of communication platforms are possible. Example devices that may be, comprise, and/or include client device  730  and/or client device  731  include, but are not limited to, example wireless capable device  2100  (described herein with reference to  FIG.  21   ) and/or example computer system  2200  (described herein with reference to  FIG.  22   ). 
     In an embodiment, computing device  750  controls and/or configures Wi-Fi radio  751  to implement a combination of frequency division multiplexing (FDM) and time division multiplexing (TDM) that alternates between communication via wireless link  741  and wireless links  742  and  743 . In other words, Wi-Fi radio  751  both switches between at least two Wi-Fi channels to implement frequency division multiplexing, and also communicates on a respective Wi-Fi channel during a respective series of non-overlapping time allocations to implement time division multiplexing. Thus, Wi-Fi radio  751  may periodically communicate with Wi-Fi access point  710  during selected time periods using a first Wi-Fi channel (a.k.a., ‘access point channel’ or ‘AP channel’), and communicate with one or more of client device  730  and client device  731  using a second Wi-Fi channel (a.k.a., ‘client channel’) during the rest of the time. In an embodiment, the time periods are selected such that wireless link  741  is configured as a high-throughput link and wireless links  742  and  743  are configured as a low-latency links. In another embodiment, the time periods are selected such that wireless link  741  is configured as a low-latency link and wireless links  742  and  743  are configured as a high-throughput links. 
     Virtual clients  756  and  757  can be used to manipulate the timing of transmissions between computing device  750  and Wi-Fi access point  710  on the AP channel. In order to manipulate the timing of communication on the AP channel, one or more of virtual client  756  and virtual client  757  can be used by computing device  750  to set busy indicators, and/or device sleep/wake indicators used by Wi-Fi access point  710 . The busy indicators, and/or device sleep/wake indicators set by one or more of clients  755 - 757  can alter the timing of transmissions of the AP channel (e.g., by setting the network access vector—NAV.) These busy indicators, and/or device sleep/wake indicators set by one or more of clients  755 - 757  can alter the timing of certain types of transmissions (e.g., broadcast or multicast transmissions) on the AP channel. 
     Wi-Fi access point  710  may be unaware that computing device  750  is using FDM-TDM channel switching to communicate via wireless links  741  and  742  using a single radio  751 . Accordingly, Wi-Fi access point  710  may function under an assumption that wireless link  741  is always on the same channel and is conforming to the Wi-Fi protocol associated with Wi-Fi access point  710 . 
     In an embodiment, computing device  750  may control radio  751  to deviate from a strict fixed time channel switching scheme in order to maintain reliable communication with both client devices  730  and  731 , and Wi-Fi access point  710 . In typical operation, computing device  750  communicates alternately with Wi-Fi access point  710  via the AP channel and with client devices  730  and  731  via the client channel. When communicating with Wi-Fi access point  710 , radio  751  is configured to use the AP channel. When communicating with client devices  730  and  731 , radio  751  is configured to use the client channel. At nominally fixed intervals (i.e., TDM), radio  751  is switched between the AP channel and the client channel (i.e., FDM) 
     Wi-Fi access point  710  may be sending (or will be unable to complete) a beacon frame when the time for an FDM-TDM channel switch between the AP channel and the client channel occurs. If the switchover of radio  751  between the AP channel and the client channel were to occur at that predetermined time, at least part of the information in the beacon frame would be missed by computing device  750 . In an embodiment, computing device  750  does not switch between channels at the predetermined time and instead delays the switch in order to complete the reception of the beacon frame from Wi-Fi access point  710 . Computing device  750  may delay the FDM-TDM channel switch by a predetermined amount of time (e.g., several milliseconds) that allows for the complete reception of any beacon frame which would not complete before the time nominally scheduled for the FDM-TDM channel switch. 
     After a FDM-TDM channel switch between the AP channel and the client channel is delayed, computing device  750  may then shorten the next (or any subsequent) time spent on the client channel. This adjustment can be used to maintain an average (or nominal) period for cycling between the AP channel and the client channel. This adjustment can also be used to help maintain a sleep/wake schedule synchronization with client devices  730  and  731 . 
     Client device  730  may be sending (or will be unable to complete) a data transmission at the time scheduled for a FDM-TDM channel switch between the client channel and the AP channel. If the switchover of radio  751  were to occur at that predetermined time, at least part of the information transmitted by client device  730  could be missed by computing device  750 . In an embodiment, computing device  750  does not switch between Wi-Fi channels at the predetermined time and instead delays the channel switch in order to complete the reception of the transmission from client device  730 . Computing device  750  may delay the FDM-TDM channel switch by a predetermined amount of time (e.g., several of milliseconds) that allows for the complete reception of any client device  730  or  731  transmission which would not complete before the time nominally scheduled for the FDM-TDM channel switch. 
     After a FDM-TDM channel switch is delayed to allow reception of the beacon frame to complete, computing device  750  may then shorten the next (or any subsequent) time allocation spent on the AP channel. This adjustment can be used to maintain an average (or nominal) period for cycling between Wi-Fi channels. This adjustment can also be used to help maintain a sleep/wake schedule synchronization with client devices  730  and  731 . 
     In an embodiment, the relative time spent communicating via the AP channel versus the client channel can be varied by computing device  750  according to the traffic on one or both of the Wi-Fi channels. In another embodiment, the relative time spent communicating via the AP channel versus the client channel can be varied by computing device  750  based on one or more of: an application being run on computing device  750 , a device classification of a client device  730  or  731  (e.g., mouse vs. keyboard vs. game controller, etc.) In this manner, throughput on the AP channel and latency the client channel can be optimized according to the activity on the channels and/or expected needs of an application and/or a client device  730  or  731 . 
     In an embodiment, computing device  750  sends scheduling and/or control information to client device  730  and client device  731  using the client channel. This information can be used to prevent, or help prevent, attempts by client device  730  and/or client device  731  to use the client channel to transmit while radio  751  is configured to listen to only the AP channel. For example, computing device  750  may send a recommended sleep duration to client device  730 . This sleep duration can be selected by computing device  750  such that client device  730  will (or is likely to) remain asleep during period(s) of time when radio  751  is configured to listen on the AP channel. 
     As described herein, computing device  750  regularly spends at least some time with radio  751  configured to communicate via the client channel. When radio  751  is configured to communicate client channel, it cannot communicate via the AP channel. In an embodiment, before performing a FDM-TDM channel switch from the AP channel to the client channel, computing device  750  sends an indicator to Wi-Fi access point  710  (e.g., using a NULL frame to specify a ‘sleep’ or ‘power save’ duration.) This indicator informs Wi-Fi access point  710  that, as far as Wi-Fi access point  710  is concerned, computing device  750  is going to sleep and will not be receiving communication via the AP channel. Wi-Fi access point  710  confirms receipt of this indicator by sending computing device  750  an acknowledgement message (e.g., ACK frame) via the AP channel. When computing device  750  receives the acknowledgement message via the AP channel, computing device  750  may perform an FDM-TDM channel switch to the client channel (or go to sleep.) 
     Wi-Fi access point  710  may not respond with the acknowledgement to the power save indicator before the predetermined time for the FDM-TDM channel switch from the AP channel to the client channel. This lack of an acknowledgement may occur because Wi-Fi access point  710  is busy with other traffic (e.g., sending a beacon frame) or interference (e.g., traffic on another wireless network operating on the same or nearby channels.) Computing device  750  may then monitor the AP channel and the client channel simultaneously. Computing device  750  may monitor the AP channel in order to receive the acknowledgement frame. Computing device  750  may monitor the client channel in order to receive transmissions from a client device  730  and respond to these transmissions within a selected maximum latency time period. Computing device  750  may monitor both the AP channel and the client channel simultaneously by receiving and demodulating communication on both the AP channel and the client channel. For example, since the AP channel and the client channel both use orthogonal frequency division multiplexing (OFDM), Computing device  750  may monitor both the AP channel and the client channel by receiving at least the OFDM carriers associated with the AP channel and the client channel, discarding data corresponding to OFDM carriers not used by the AP channel and the client channel (e.g., intervening channels when the AP channel and the client channel are on non-contiguous Wi-Fi channels), and then separately (i.e., by channel) processing the data associated with the respective OFDM carriers for the AP channel and the client channel. In an embodiment, appropriate filters and/or filter banks may be used for performing the desired separation. 
     Computing device  750  may have data to transmit to client device  730  when Wi-Fi access point  710  has not responded to the power save indicator before the predetermined time for the FDM-TDM channel switch from the AP channel to the client channel. To prevent Wi-Fi access point  710  from transmitting on the AP channel while computing device  750  is transmitting data to a client device  730  or  731  after the switch to the client channel, computing device  750  can send a transmission on the AP channel. This transmission is sent associated with an identifier (e.g., MAC address) such that the transmission appears to be from a device that is not connected to Wi-Fi access point  710 . This transmission can indicate a transmission duration that corresponds to the time the computing device  750  needs to transmit on the client channel. In this manner, the Wi-Fi collision avoidance algorithm used by Wi-Fi access point  710  will prevent the Wi-Fi access point  710  from transmitting on the client channel for the specified transmission duration. After computing device  750  has completed its transmission on the client channel, computing device  750  can switch into the aforementioned mode whereby computing device  750  simultaneously monitors the AP channel and the client channel. 
     To prevent (or help prevent) cases where Wi-Fi access node  710  is delayed from sending an acknowledgment due to a beacon frame transmission (or impending beacon frame transmission), computing device  750  can adjust the time allocations (and/or timing of the FDM-TDM channel switches) spent the AP channel and the client channel such that the beacon frame transmissions occur while radio  751  is known to be (or very likely to be) configured to be on the AP channel. 
     Broadcast or multicast frames being sent by Wi-Fi access point  710  may also cause computing device  750  and/or Wi-Fi access point  710  from communicating or responding to a power save message. Computing device  750  can send a transmission on the AP channel that appears to be from a device that is connected to Wi-Fi access point  710 , but where that device is not identified (e.g., by MAC address) as being computing device  750  (i.e., a ‘virtual’ client of Wi-Fi access point  710  created by computing device  750  for this purpose.) This transmission can indicate to Wi-Fi access point  710  that the virtual client device will be sleeping at all times except those close to the beacon time. Since broadcast/multicast frames are sent at times when all of the clients of Wi-Fi access point  710  are awake, Wi-Fi access point  710  will be constrained to scheduling broadcast/multicast frames close to the beacon time. This at least limits the effect of broadcast/multicast frames to switchover times that are close to the beacon time. 
     Aggregated frames being sent by Wi-Fi access point  710  may also cause computing device  750  and/or Wi-Fi access node  710  from communicating or responding to a power save message. Since Wi-Fi access point  710  is busy sending these aggregated frames, computing device  750  may not be able to send the power save indicator to Wi-Fi access point  710  and/or receive an acknowledgement. When this occurs, computing device  750  may elect to continue to switch between the AP channel and the client channel according to the FDM-TDM time allocations without informing Wi-Fi access point  710  that computing device  750  is going to sleep. By continuing to switch channels without informing Wi-Fi access point  710 , computing device  750  may switch away from the AP channel and the client channel and then back to the AP channel before the aggregated frame transmission completes. By returning to the AP channel before the frame transmission completes, computing device  750  may not miss a transmission from Wi-Fi access point  710 , or need to re-establish link  741 . 
       FIG.  8    is a flowchart illustrating a method for setting a transmission time by a client device. The steps illustrated in  FIG.  8    may be performed by one or more elements of communication system  100  and/or communication system  700 . A low-latency link that uses a first frequency band and a first series of time allocations is configured ( 802 ). For example, client device  730  and computing device  750  and Wi-Fi access point  710  may establish and provision link  742  on the client channel. Computing device  750  may set parameters (such as time intervals/allocations for FDM-TDM channel switching) that allow client device  730  to communicate with computing device  730  via the client channel. 
     A time indicator from the access point is received via the low-latency link ( 804 ). For example, client device  730  may receive a time indicator  653  from computing device  750  instructing client device  730  to ‘wake up’ at a selected time (or, equivalently, is to remain ‘asleep’ for a selected period). In response to the time indicator, the client device is configured to select a transmit/wake-up time that is during a first one of the first series of time allocations ( 804 ). For example, in response to time indicator  653 , client device  730  can configure itself to wake up at a time corresponding the time indicator  653  received from computing device  750 . Computing device  750  can select this wake up time can fall within a time allocation for the client channel (e.g., transmission  654 .) 
     Optionally, if there is a collision at the selected transmit/wake-up time, a new transmit/wake-up time is selected ( 808 ). For example, if, at the transmit/wake-up time, client device  730  detects that another device is transmitting at that time, client device  730  can select a new time to wake-up/transmit according a Wi-Fi collision avoidance procedure. 
       FIG.  9    is a diagram illustrating multi-channel reception by a single radio. As discussed herein, computing device  750  can monitor both the AP channel and the client channel. In  FIG.  9   , an example channel spectrum of Wi-Fi channel 1 (e.g., the AP channel) and Wi-Fi channel 6 (e.g., the client channel) are illustrated. Both channels are demodulated into OFDM carriers. Both channels may be demodulated into OFDM carriers by configuring radio  751  as if radio  751  were receiving a 40 MHz wide Wi-Fi channel that encompasses the two 20 MHz Wi-Fi channels 1 and 6. Alternatively, configuring radio  751  as if radio  751  were receiving an 80 MHz Wi-Fi channel can be used to receive contiguous or non-contiguous 20 MHz Wi-Fi channels, or contiguous 40 MHz wide channels. Likewise, configuring radio  751  as if radio  751  were receiving a 160 MHz Wi-Fi channel can be used to receive contiguous or non-contiguous 20 or 40 MHz Wi-Fi channels, or contiguous 80 MHz wide channels. 
       FIG.  10    is a diagram illustrating multi-channel reception to prevent holdover. In  FIG.  10   , the horizontal axis represents time, and the vertical axis represents frequency. A first Wi-Fi channel is shown above the horizontal axis. A second Wi-Fi channel is shown below the horizontal axis. The first Wi-Fi channel is operated to be a high-throughput link and is therefore denoted the AP channel in  FIG.  10   . This first frequency band can correspond to the channel used by link  741  between computing device  750  and Wi-Fi access point  710 . The second frequency band is operated to be a low-latency link and is therefore denoted the client channel in  FIG.  10   . This second frequency band can correspond to the channel used by links  142  and  143  between computing device  750  and client devices  730  and  731 , respectively. 
       FIG.  10    illustrates successive time allocations  1010 ,  1011 ,  1012 , and  1013  on the AP channel. Also illustrated are time allocations  1021  and  1022  on the client channel. Allocation  1021  corresponds in time to allocation  1010 . Allocation  1022  corresponds in time to allocation  1012 . Allocations  1011 ,  1013 ,  1021  and  1022  are labeled to indicate both receiving and transmitting activities. Allocations  1010  and  1012  are labeled to indicate just receiving. It should be understood that radio  751  may not be able to simultaneously transmit and receive on a channel. Thus, in this case, it should be understood that the transmit and receive activities of radio  751  are time-division multiplexed according to the specified protocol on the respective channel. For example, radio  751  may spend part of the time in allocation  1011  receiving and part of the time transmitting. The switching between receiving and transmitting may be governed by the Wi-Fi protocol. In another example, radio  751  may spend part of the time in allocation  1022  receiving and part of the time transmitting. The switching between receiving and transmitting may be governed by the latency optimized client network protocol being used on the client channel. 
     In allocation  1011 , a power save (i.e., ‘going to sleep’) indicator  1051  is transmitted. Indicator  1051  is transmitted by computing device  750 . In allocation  1012 , an acknowledgement  1052  to indicator  1051  is transmitted. Acknowledgement  1052  is transmitted by Wi-Fi access point  710  in response to receiving indicator  1051 . It should be noted, however, that since allocation  1012  and allocation  1022  correspond in time, and allocation  1022  is nominally for client channel  1022 , computing device  750  configures radio  751  in the multi-channel reception mode described herein (as further detailed herein with reference to at least  FIG.  9    as an example). With radio  751  operating such that it can receive on the AP channel while both receiving and transmitting on the client channel, computing device  750  is able to receive acknowledgment  1052  in allocation  1012 . 
       FIG.  11    is a diagram illustrating multi-channel transmission. In  FIG.  11   , the horizontal axis represents time, and the vertical axis represents frequency. A first Wi-Fi channel is shown above the horizontal axis. A second Wi-Fi channel is shown below the horizontal axis. The first Wi-Fi channel is operated to be a high-throughput link and is therefore denoted AP channel in  FIG.  11   . This first frequency band can correspond to the channel used by link  741  between computing device  750  and Wi-Fi access point  710 . The second frequency band is operated to be a low-latency link and is therefore denoted client channel in  FIG.  11   . This second frequency band can correspond to the channel used by link  142  and  143  between computing device  750  and client devices  730  and  731 , respectively. 
       FIG.  11    illustrates successive time allocations  1110 ,  1111 ,  1112 , and  1113  on the AP channel. Also illustrated are successive allocations  1120 ,  1121 , and  1122  on the client channel. Allocation  1120  corresponds in time to allocation  1110 . Allocation  1121  corresponds in time to allocation  1111 . Allocation  1122  corresponds in time to allocation  1112 . In allocation  1110  a busy indicator (NAV)  1153  is transmitted by computing device  750  on the AP channel. In allocation  1120  (possibly simultaneous with busy indicator  1153 ) a busy indicator (NAV)  1153  is transmitted by computing device  750  on the client channel. In an embodiment, busy indicators  1153  and  1154  correspond to the Wi-Fi network access vector (NAV) in a Wi-Fi frame. It should be noted, that since busy indicator  1153  and busy indicator  1154  correspond in time, and busy indicator  1153  is not associated with a device that is connected on the AP channel, Wi-Fi access point  710  will respond to busy indicator  1153  by treating the AP channel as busy for all (or part—as specified by indicator  1153 ) of allocation  1111 . Thus, Wi-Fi access point  710  will not transmit during allocation  1111  on the AP channel thereby allowing computing device  750  to transmit and receive on (at least) the client channel during allocation  1121 . 
       FIG.  12    is a diagram illustrating client device following. When computing device  750  is operating on the client channel, client device  730  sends communication #1 to computing device  750  via the client channel. In response, computing device  750  sends a response back to client device  730  via the client channel. This is normal operation during FDM-TDM allocations on the client channel. 
     After a FDM-TDM channel switch has occurred and computing device  750  is operating on the AP channel, client device  730  sends communication #2 to computing device  750  via the client channel. However, since computing device  750  is operating on the AP channel, computing device  750  does not receive communication #2 and therefore does not send a response to client device  730  via the client channel. 
     Responsive to not receiving a response via the client channel, client device  730  resends communication #2 via the AP channel. This time, since computing device  750  is operating on the AP channel, computing device  750  receives the retried communication #2 via the AP channel and therefore sends a response to client device  730  via the AP channel. In response to receiving the response via the AP channel, client device  730  send communication #3 via the AP channel. Thus, it should be understood that in an embodiment, client device  730  can ‘follow’ computing device  750  from the client channel to the AP channel (and back). 
       FIG.  13    is a diagram that illustrates setting an access node transmission time. The processes illustrated in  FIG.  13    may be performed by one or more elements of communication system  100  and/or communication system  700 . At the start of the diagram, ‘real’ client  755  of computing device  750  and ‘virtual’ client  756  are connected to Wi-Fi access point  710 . Virtual client  757 , however, is not (and normally will never be) connected to Wi-Fi access point  710 . Client  755  of computing device  750  sends a power save (or ‘sleep’) indicator message to Wi-Fi access point  710  via the AP channel. Computing device  750  may have client  755  send the indicator message to Wi-Fi access point  710  so that computing device  750  will appear ‘asleep’ to Wi-Fi access point  710 . This allows computing device  750  to configure radio  751  to operate on the client channel during a client channel time allocation. However, for at least one of the reasons described herein (e.g., Wi-Fi access point  710  is busy with other traffic, beacon frame, etc.) Wi-Fi access point  710  does not send a response to computing device  750 . 
     In response to not receiving a response from Wi-Fi access point  710  via the AP channel, computing device  750  has virtual client  757  send a transmission on the AP channel. This transmission includes a network access vector (NAV) selected to give computing device  750  (and client  755  of computing device  750 , in particular) time to operate on the client channel by making the AP channel appear to be busy to Wi-Fi access point  710 . When the time set by virtual client  757  expires, Wi-Fi access point  710  can send a transmission to computing device  750  (and client  755  of computing device  750 , in particular) via the AP channel. 
       FIG.  14    is a diagram that illustrates setting a broadcast/multicast transmission time. The processes illustrated in  FIG.  13    may be performed by one or more elements of communication system  100  and/or communication system  700 . At the start of the diagram, ‘real’ client  755  of computing device  750  and ‘virtual’ client  756  are connected to Wi-Fi access point  710 . Virtual client  757 , however, is not (and normally will never be) connected to Wi-Fi access point  710 . Virtual client  756  of computing device  750  sends a power save (or ‘sleep’) indicator message to Wi-Fi access point  710  via the AP channel. Computing device  750  has client  756  send this indicator message to Wi-Fi access point  710  so that virtual client  756  will appear ‘asleep’ to Wi-Fi access point  710 . Computing device  750  times the sending of this indicator message to Wi-Fi access point  710  so that virtual client  756  will only appear ‘awake to Wi-Fi access point  710  around time that Wi-Fi access point  710  will be sending a beacon frame. Since broadcast/multicast frames are only sent when all the clients connected to Wi-Fi access point  710  (i.e., client  755  and virtual client  756 ) are awake, broadcast/multicast frames are confined to being sent during the ‘awake’ times of virtual client  756 . Thus, the sleep/wake times of virtual client  756  can be used to control when broadcast/multicast frames are sent by Wi-Fi access point  710 . 
     After receiving the power save message from virtual client  756 , Wi-Fi access point  710  waits for the ‘media busy’ time set by virtual client  756  to expire. When the time set by virtual client  756  expires, Wi-Fi access point  710  can send broadcast/multicast frames to computing device  750  (and client  755  of computing device  750 , in particular) via the AP channel. 
       FIG.  15    is a diagram illustrating time allocations to receive beacon transmissions. In  FIG.  15   , beacon transmissions  1561 ,  1562 , and  1563  by Wi-Fi access point  710  are illustrated. In addition, AP channel allocations  1511 ,  1512 ,  1513 ,  1514 , and  1515 , and client channel allocations  1521 ,  1522 ,  1523 , and  1524  are illustrated. In  FIG.  15   , AP allocations AP channel allocations  1511 ,  1512 ,  1513 ,  1514 , and  1515 , alternate with, but do not overlap in time, client channel allocations  1521 ,  1522 ,  1523 , and  1524 . AP allocations  1511 ,  1513 , and  1515 , however, are timed so that computing device  750  can receive beacon transmissions  1561 ,  1562 , and  1563 . This is illustrated in  FIG.  15   , respectively, by arrow  1571  between beacon  1561  and allocation  1511 , arrow  1572  between beacon  1562  and allocation  1513 , and arrow  1573  between beacon  1563  and allocation  1515 . 
       FIG.  16    is a diagram illustrating an aggregated frame transmission. In  FIG.  1165   , aggregated frame transmission  1661  by Wi-Fi access point  710  is illustrated. In addition, AP channel allocations  1611 ,  1612 ,  1613 ,  1614 , and  1615 , and client channel allocations  1621 ,  1622 ,  1623 , and  1624  are illustrated. In  FIG.  16   , AP allocations AP channel allocations  1611 ,  1612 ,  1613 ,  1614 , and  1615 , alternate with, but do not overlap in time, client channel allocations  1621 ,  1622 ,  1623 , and  1624 . Aggregated frame transmission  1661 , however, begins during AP channel allocation  1611 , continues through client allocation  1621 , and ends during AP channel allocation  1612 . Thus, since access point was transmitting during the entire time computing device  750  was operating on the client channel, computing device  750  does not miss any data from Wi-Fi access point  710 . 
       FIG.  17    is a flowchart illustrating a method of operating a communication system. The steps illustrated in  FIG.  17    may be performed by one or more elements of communication system  100  and/or communication system  700 . A first wireless interface link is established to communicate with an access node using a first channel of a frequency band ( 1702 ). For example, computing device  750  may establish link  741  with Wi-Fi access point  710  using a channel designated as the AP channel. The AP channel is specified as one of a plurality of channels of a country dependent Wi-Fi frequency band. A second wireless interface link is established to communicate with a client device using a second channel of the frequency band ( 1702 ). For example, computing device  750  may establish link  742  with client device  730  using a channel designated, by computing device  750 , as the client channel. Like the AP channel, the client channel is specified as one of a plurality of channels of a country dependent Wi-Fi frequency band. 
     Via the first wireless interface link, a first message to the access node indicating the first wireless interface link is to enter a dormant state is sent ( 1706 ). For example, computing device  750  may send, to Wi-Fi access point  710 , a power save indicator informing Wi-Fi access point  710  that computing device  750  will not be in communication for a period of time. 
     Data from the access node via the first channel and data from the client device via the second channel is concurrently received by demodulating a wide channel comprising the first channel and the second channel. The concurrently received data including an indicator that the access node has received the first message ( 1708 ). For example, radio  751  may be configured to receive, demodulate, separate, and decode the OFDM carriers of the AP channel and the client channel as described herein (e.g., by demodulating a 40 MHz channel comprising two 20 MHz channels.) This allows computing device  750  to monitor the AP channel for an acknowledgement from Wi-Fi access point  710 , and to monitor the client channel for a communication from a client device  730 . 
       FIG.  18    is a flowchart illustrating a method of operating a client device. The steps illustrated in  FIG.  18    may be performed by one or more elements of communication system  100  and/or communication system  700 . A low-latency link between a client device and a soft access point is configured ( 1802 ). In an embodiment, the low-latency link uses a first frequency band and a first series of time allocations while a second (e.g., high-throughput) link uses a second frequency band and a second series of time allocations. For example, client device  730  and computing device  750  may be configured to communicate via link  742  while computing device  750  and Wi-Fi access point  710  are configured to communicate via link  741 . 
     Via the low-latency link, a first message to the soft access point using the first frequency band and a one of a series of time allocations is sent ( 1804 ). For example, client device  730  may send a Wi-Fi frame to computing device  750  using the client channel during a time allocation designated for operating on the client channel. 
     In response to not receiving, via the first frequency band, an acknowledgement associated with the first message, a retry of the first message using a second frequency band and during the one of the series of time allocations is sent ( 1806 ). For example, in response to not receiving an acknowledgement of the client channel, client device  730  may send a retry of the Wi-Fi frame, during the time allocation designated for operating on the client channel, to computing device  750 , using the AP channel. 
     In response to receiving, via the second frequency band, an acknowledgement associated with the retry of the first message, a second message to the soft access point is sent using the second frequency band and is sent during the one of the series of time allocations ( 1808 ). For example, client device  730  may send, in response to receiving an acknowledgement of the retry frame, additional messages/data during the time allocation designated for operating on the client channel, to computing device  750 , using the AP channel. 
       FIG.  19    is a flowchart illustrating a method of using a connected virtual client to constrain access point transmission timing. The steps illustrated in  FIG.  19    may be performed by one or more elements of communication system  100  and/or communication system  700 . A wireless interface radio is configured to communicate with a first access node using a first frequency band and a first series of time allocations ( 1902 ). For example, radio  751  of computing device  750  may be configure by computing device  750  to communicate with Wi-Fi access point  710  using the AP channel during time allocations designated for operating using the AP channel. 
     The wireless interface radio is configured to communicate with a client device using a second frequency band and a second series of time allocations ( 1904 ). For example, radio  751  of computing device  750  may be configured by computing device  750  to communicate with Wi-Fi device  730  using the client channel during time allocations designated for operating using the client channel. 
     With the access node, a first wireless communication link associated with a first MAC identifier is established ( 1906 ). For example, computing device  750  may establish a connection for client  755  with Wi-Fi access point  710 . With the access node, a second wireless communication link associated with a second MAC identifier is established ( 1908 ). For example, computing device  750  may establish a connection for virtual client  756  with Wi-Fi access point  710 . 
     Information to constrain a timing that the access node will schedule at least one transmission is transmitted associated to the second MAC identifier ( 1910 ). For example, computing device  750  may have radio  751  make a transmission that is identified as coming from virtual client  756 . This transmission can set sleep/wake parameters used by Wi-Fi access point  710  to determine when to send certain transmissions (e.g., broadcast/multicast transmissions). By setting these parameters with the transmission that was identified as coming from virtual client  756 , computing device  750  can constrain the timing of future transmissions by Wi-Fi access point  710 . 
       FIG.  20    is a flowchart illustrating a method of using a connected virtual client to constrain access point transmission timing. The steps illustrated in  FIG.  20    may be performed by one or more elements of communication system  100  and/or communication system  700 . A wireless interface radio is configured to communicate with a first access node using a first frequency band and a first series of time allocations ( 2002 ). For example, radio  751  of computing device  750  may be configured by computing device  750  to communicate with Wi-Fi access point  710  using the AP channel during time allocations designated for operating using the AP channel. 
     The wireless interface radio is configured to communicate with a client device using a second frequency band and a second series of time allocations ( 2004 ). For example, radio  751  of computing device  750  may be configure by computing device  750  to communicate with Wi-Fi device  730  using the client channel during time allocations designated for operating using the client channel. 
     With the access node, a first wireless communication link associated with a first MAC identifier is established ( 2006 ). For example, computing device  750  may establish a connection for client  755  with Wi-Fi access point  710 . 
     Information to constrain a timing that the access node will schedule at least one transmission is transmitted associated to a second MAC identifier that is not associated with a wireless communication link with the access node ( 2008 ). For example, computing device  750  may have radio  751  make a transmission that is identified as coming from virtual client  757 . This transmission can set busy/free parameters used by Wi-Fi access point  710  that determine when to send certain transmissions (e.g., broadcast/multicast transmissions). By setting these parameters with the transmission that was identified as coming from virtual client  757 , computing device  750  can constrain the timing of future transmissions by Wi-Fi access point  710 . 
     Many of the functions, protocols, etc. described above may be implemented with, contain, or be executed by one or more computer systems, processing circuits, hardware state machines, or other circuit blocks and/or circuit partitions. The methods described above may also be stored on a non-transitory computer readable medium and/or implemented by state machines. Many of the elements of communication system  100 , and/or communication system  700  may be, comprise, or include wireless capable devices and/or nodes. This includes, but is not limited to: wireless network access node  110 , client device  130 , computing device  150 , Wi-Fi access node  710 , client device  730 , client device  731 , and/or computing device  750 . 
       FIG.  21    is a block diagram illustrating portions of an example wireless capable device. Wireless capable device  2100  comprises antenna  2106 , transceiver circuit  2104 , collision avoidance circuit  2110 , tuner circuit  2108 , timer circuit  2112 , wireless interface layer control circuit  2114 , higher level network protocol circuit  2116 , and processor  2118 . antenna  2106 , transceiver circuit  2104 , collision avoidance circuit  2110 , tuner circuit  2108 , timer circuit  2112 , wireless interface layer control circuit  2114  may cooperate to implement one or more of the lower layers (e.g., physical layer 1) of the Open Systems Interconnect (OSI) model and the additional or modified functions associated with that layer described herein. Processor  2118  and higher level network protocol circuit  2116  may cooperate to implement one or more of the higher layers (e.g., MAC or IP layer) of the Open Systems Interconnect and the additional or modified functions of those layers described herein. 
     The methods, systems and devices described above may be implemented in computer systems, or stored by computer systems. The methods described above may also be stored on a non-transitory computer readable medium. Devices, circuits, and systems described herein may be implemented using computer-aided design tools available in the art, and embodied by computer-readable files containing software descriptions of such circuits. This includes, but is not limited to one or more elements of wireless network access node  110 , client device  130 , computing device  150 , Wi-Fi access node  710 , client device  730 , client device  731 , and/or computing device  750 , communication system  100 , and/or communication system  700 , and their components. These software descriptions may be: behavioral, register transfer, logic component, transistor, and layout geometry-level descriptions. 
     Data formats in which such descriptions may be implemented are stored on a non-transitory computer readable medium include, but are not limited to: formats supporting behavioral languages like C, formats supporting register transfer level (RTL) languages like Verilog and VHDL, formats supporting geometry description languages (such as GDSII, GDSIII, GDSIV, CIF, and MEBES), and other suitable formats and languages. Physical files may be implemented on non-transitory machine-readable media such as: 4 mm magnetic tape, 8 mm magnetic tape, 3½-inch floppy media, CDs, DVDs, hard disk drives, solid-state disk drives, solid-state memory, flash drives, and so on. 
     Alternatively, or in addition, the functionally described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc. 
       FIG.  22    illustrates a block diagram of an example computer system. Computer system  2200  includes communication interface  2220 , processing system  2230 , storage system  2240 , and user interface  2260 . Processing system  2230  is operatively coupled to storage system  2240 . Storage system  2240  stores software  2250  and data  2270 . Processing system  2230  is operatively coupled to communication interface  2220  and user interface  2260 . Computer system  2200  may comprise a programmed general-purpose computer. Computer system  2200  may include a microprocessor. Computer system  2200  may comprise programmable or special purpose circuitry. Computer system  2200  may be distributed among multiple devices, processors, storage, and/or interfaces that together comprise elements  2220 - 2270 . 
     Communication interface  2220  may comprise a network interface, modem, port, bus, link, transceiver, or other communication device. Communication interface  2220  may be distributed among multiple communication devices. Processing system  2230  may comprise a microprocessor, microcontroller, logic circuit, or other processing device. Processing system  2230  may be distributed among multiple processing devices. User interface  2260  may comprise a keyboard, mouse, voice recognition interface, microphone and speakers, graphical display, touch screen, or other type of user interface device. User interface  2260  may be distributed among multiple interface devices. Storage system  2240  may comprise a disk, tape, integrated circuit, RAM, ROM, EEPROM, flash memory, network storage, server, or other memory function. Storage system  2240  may include computer readable medium. Storage system  2240  may be distributed among multiple memory devices. 
     Processing system  2230  retrieves and executes software  2250  from storage system  2240 . Processing system  2230  may retrieve and store data  2270 . Processing system  2230  may also retrieve and store data via communication interface  2220 . Processing system  2250  may create or modify software  2250  or data  2270  to achieve a tangible result. Processing system may control communication interface  2220  or user interface  2260  to achieve a tangible result. Processing system  2230  may retrieve and execute remotely stored software via communication interface  2220 . 
     Software  2250  and remotely stored software may comprise an operating system, utilities, drivers, networking software, and other software typically executed by a computer system. Software  2250  may comprise an application program, applet, firmware, or other form of machine-readable processing instructions typically executed by a computer system. When executed by processing system  2230 , software  2250  or remotely stored software may direct computer system  2200  to operate as described herein. 
     In an embodiment, a method of operating a communication system, includes: configuring a wireless interface radio to communicate with an access node using a first frequency band and a first series of time allocations; configuring the wireless interface radio to communicate with at least one client device using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; and, sending, via the second frequency band and to at least one client device, information to be used by the at least one client device to select a time to transmit using the second frequency band; and, based on a transmission received via the wireless interface radio, altering a first duration of a first time allocation of at least one of the first series of time allocations and the second series of time allocations. 
     The transmission may be received using the first frequency band. The first time allocation may be from the first series of time allocations. The first duration of the first time allocation may be increased in response to the transmission received using the first frequency band. A second duration of a second time allocation from the second series of time allocations may be decreased in response to the transmission received using the first frequency band. 
     The transmission may be received using the second frequency band where the first time allocation is from the second series of time allocations, and the duration of the first time allocation is increased in response to the transmission received using the second frequency band. A second duration of a second time allocation from the first series of time allocations may be decreased in response to the transmission received using the second frequency band. 
     In an embodiment, a method of operating a communication system, includes: configuring a high-throughput link that uses a wireless interface radio to communicate with an access node using a first frequency band and a first series of time allocations; configuring a low-latency link that uses the wireless interface radio to communicate with at least one client device using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; and, sending, to a first client device communicating via the second frequency band, a first time indicator, the first client device to, in response to the first time indicator, select a first time to transmit that is during a one of the second series of time allocations. The first time indicator may correspond to a time that is referenced with respect to a boundary between time allocations of the first series of time allocations and the second series of time allocations. 
     This method may also include sending, to a second client device communicating via the second frequency band, a second time indicator, the second client device to, in response to the second time indicator, select a second time to transmit that is during a one of the second series of time allocations and does not collide with the first time to transmit selected by the first client device. 
     This method may also include altering, based on a transmission received from the first client device, a first duration of a first time allocation of at least one of the first series of time allocations and the second series of time allocations. In response to the transmission received from the first client device, the first duration may be increased by a first amount. In response to the transmission received from the first client device, a second time allocation of following the first time allocation may be decreased by the first amount. The second time allocation may belong to the second series of time allocations. 
     In an embodiment a wireless capable device comprises a wireless interface radio to communicate with a first device using a first frequency band and a first series of time allocations. This first frequency band and first series of time allocations are to be used as a high-throughput link. The wireless interface radio is to also communicate with at least a second device using a second frequency band and a second series of time allocations. This second frequency band and second series of time allocations to be used as a low-latency link. The first series of time allocations and the second series of time allocations are to be non-overlapping. The wireless capable device also comprises a wireless interface layer control circuit to control the wireless interface radio. The wireless interface layer control circuit is to control the wireless interface radio to send, to the second device communicating via the second frequency band, a first time indicator. The second device is to, in response to the first time indicator, select a first time to transmit that is during a one of the second series of time allocations. 
     The first device may be an access node. The second device may be a client device. The first time indicator may correspond to a time that is referenced with respect to a boundary between time allocations of the first series of time allocations and the second series of time allocations. The wireless interface layer control circuit may also control the wireless interface radio to send, to a third device communicating via the second frequency band, a second time indicator. The second client device is to, in response to the second time indicator, select a second time to transmit that is during a one of the second series of time allocations and does not collide with the first time to transmit selected by the second device. 
     Based on a transmission received from the second device, the wireless device may alter a first duration of a first time allocation of at least one of the first series of time allocations and the second series of time allocations. In response to the transmission received from the second device, the wireless device may increase the first duration by a first amount. In response to the transmission received from the second device, the wireless device may decrease a second time allocation that follows the first time allocation by the first amount. The second time allocation may belong to the second series of time allocations. 
     In an embodiment, a method of operating a client device includes: configuring a low-latency link between the client device and an access point, the low-latency link to use a first frequency band and a first series of time allocations, the access point to communicate with a network access node using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; receiving, from the access point and via the low-latency link, a first time indicator; and, in response to the time indicator, configuring the client device to select a first selected transmit time that is during a first one of the first series of time allocations. The first time indicator may correspond to a time that is referenced with respect to a boundary between time allocations of the first series of time allocations and the second series of time allocations. 
     This method may also include sending, to a second client device communicating via the second frequency band, a second time indicator, the second client device to, in response to the second time indicator, select a second time to transmit that is during a one of the second series of time allocations and does not collide with the first time to transmit selected by the first client device. 
     This method may also include, altering, based on a transmission received from the first client device, a first duration of a first time allocation of at least one of the first series of time allocations and the second series of time allocations. In response to the transmission received from the first client device, the first duration may be increased by a first amount. In response to the transmission received from the first client device, a second time allocation following the first time allocation may be decreased by the first amount. The second time allocation may belong to the second series of time allocations. 
     In an embodiment, a method of operating a client device includes configuring a low-latency link between the client device and a wireless interface of a computing device, the low-latency link to use a first frequency band and a first series of time allocations, the wireless interface to communicate with a network access node using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; receiving, from the wireless interface and via the low-latency link, a first time indicator; and, in response to the time indicator, configuring the client device to select a first selected transmit time that is during a first one of the first series of time allocations. 
     This method may also include detecting that another device is transmitting at the first selected transmit time; and, in response to detecting that another device is transmitting at the selected transmit time, selecting a second transmit time. The second transmit time may be selected according to a wireless standard specified collision avoidance algorithm performed by the client device. The second transmit time may be selected to be during the first one of the first series of time allocations. The second transmit time may be selected to be during a second one of the first series of time allocations. The first time indicator may correspond to a time that is referenced with respect to a boundary between time allocations of the first series of time allocations and the second series of time allocations. 
     In an embodiment, a method of operating a communication system, includes: establishing a first wireless interface link to communicate with an access node using a first channel of a frequency band; establishing a second wireless interface link to communicate with a client device using a second channel of the frequency band; sending, via the first wireless interface link, a first message to the access node indicating the first wireless interface link is to enter a first dormant state; and, concurrently receiving data from the access node using the first channel and the client device using the second channel by demodulating a wide channel comprising the first channel and the second channel, the concurrently received data including an indicator that the access node has received the first message indicating the first wireless interface link is to enter the first dormant state. The indicator that the access node has received the first message may be received via the first channel. The concurrently received data may include a second indicator that the client device has exited a second dormant state where this second indicator is received via the second channel. 
     The concurrently received data may include an indicator that the client device has exited a second dormant state. The indicator that the client device has exited the second dormant state may be received via the first channel. The indicator that the client device has exited the second dormant state may be received via the second channel. 
     This method may also include concurrently sending a second message to the access node and a third message to the client device, the second message being sent using the first channel and the third message being sent using the second channel, the first message indicating to the access point that the first message is to keep the first channel busy for an indicated period of time, the second message to be sent to the client device using the second channel during the indicated period of time. The concurrently received data may include an indicator that the client device is requesting to communicate via the second link, and the third message is a response to the request to communicate via the second link. 
     In an embodiment, a method of operating a client device, including: configuring a low-latency link between the client device and a soft access point device, the low-latency link to use a first frequency band and a first series of time allocations, the soft access point device to also communicate with a network access node using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; transmitting, via the low-latency link, a first message to the soft access point using the first frequency band during a first one of the first series of time allocations; in response to not receiving, via the first frequency band, a first acknowledgement associated with the first message, sending a first retry of the first message to the soft access point using the second frequency band during the first one of the first series of time allocations; and, in response to receiving, via the second frequency band, a second acknowledgment associated with the first retry of the first message, sending a second message to the soft access point using the second frequency band during the first one the first series of time allocations. 
     This method may also: send, in response to not receiving the second acknowledgement associated with the retry of the first message, a second retry of the first message to the soft access point using the first frequency band during the first one of the first series of time allocations; and, in response to receiving, via the first frequency band, a second acknowledgment associated with the second retry of the first message, send a third message to the soft access point using the first frequency band during the first one of the first series of time allocations. 
     In an embodiment, a method of operating a communication system, including: configuring a wireless interface radio to communicate with a first access node using a first frequency band and a first series of time allocations; configuring the wireless interface radio to communicate with at least one client device using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; establishing, with the access node, a first wireless communication link associated with first media access control (MAC) identifier; establishing, with the access node, a second wireless communication link associated with a second MAC identifier; and, transmitting information, associated with the second MAC identifier, to constrain a timing that the access node will schedule at least one transmission by the access node. 
     The transmitted information associated with the second MAC identifier can prevent a transmission by the access node that would start during a one of second series of time allocations but not end before an end of the one of the second series of time allocations. The transmitted information may constrain the timing that the access node schedules a broadcast frame. The transmitted information may constrain the timing that the access node schedules a multicast frame. The transmitted information associated with the third MAC identifier can prevent a transmission by the access node during a period of time that the wireless interface radio is to communicate with at least one client device using the second frequency band. 
     This method may also transmit information, associated with a third MAC identifier, to constrain a timing that the access node will schedule at least one transmission by the access node, where the second MAC identifier is not associated with a wireless communication link with the access node. 
     This method may also receive, from a client device and via the first frequency band and during a one of the second series of time allocations, a retry of a first message that was previously sent by the client device using the second frequency band during the one of the second series of time allocations. This method may also transmit, to the client device and via the first frequency band and during the one of the second series of time allocations, a response to the retry of the first message. 
     In an embodiment, a wireless capable device comprises a wireless interface radio to communicate with an access node using a first frequency band and a first series of time allocations. The first frequency band and first series of time allocations are to be used as a high-throughput link. The wireless interface radio is to also communicate with at least one client device using a second frequency band and a second series of time allocations. The second frequency band and a second series of time allocations are to be used as a low-latency link. The first series of time allocations and the second series of time allocations are to be non-overlapping. The wireless capable device also comprises a wireless interface layer control circuit to establish, with the access node, a first wireless communication link associated with first media access control (MAC) identifier. The wireless interface layer control circuit to also establish, with the access node, a second wireless communication link associated with a second MAC identifier. The wireless interface radio to also transmit information associated with the second MAC identifier to constrain a timing that the access node will schedule at least one transmission by the access node. 
     The transmitted information associated with the second MAC identifier may prevent a transmission by the access node that would start during a one of second series of time allocations, but not end before an end of the one of the second series of time allocations. The transmitted information associated with the second MAC identifier may constrain the timing that the access node schedules a broadcast frame. The transmitted information associated with the second MAC identifier may constrain the timing that the access node schedules a multicast frame. 
     The wireless interface radio may also transmit information associated with a third MAC identifier to constrain a timing that the access node will schedule at least one transmission by the access node where the second MAC identifier is not associated with a wireless communication link with the access node. The transmitted information associated with the third MAC identifier may prevent a transmission by the access node during a period of time that the wireless interface radio is to communicate with at least one client device using the second frequency band. The wireless interface radio may also receive, from a client device and via the first frequency band and during a one of the second series of time allocations, a retry of a first message that was previously sent by the client device using the second frequency band during the one of the second series of time allocations. The wireless interface radio may also transmit, to the client device and via the first frequency band and during the one of the second series of time allocations, a response to the retry of the first message. 
     In an embodiment, a method of operating a communication system, includes: configuring a wireless interface radio to communicate with a first access node using a first frequency band and a first series of time allocations; configuring the wireless interface radio to communicate with at least one client device using a second frequency band and a second series of time allocations, the first series of time allocations and the second series of time allocations to be non-overlapping; establishing, with the access node, a first wireless communication link associated with first media access control (MAC) identifier; and, transmitting information, associated with a second MAC identifier, to constrain a timing that the access node will schedule at least one transmission by the access node, the second MAC identifier not associated with a wireless communication link with the access node. 
     The transmitted information associated with the second MAC identifier can prevent a transmission by the access node during a period of time that the wireless interface radio is to communicate with at least one client device using the second frequency band. The transmitted information may constrain the timing that the access node schedules a broadcast frame. The transmitted information may constrain the timing that the access node schedules a multicast frame. 
     This method may also receive, from a client device and via the first frequency band and during a one of the second series of time allocations, a retry of a first message that was previously sent by the client device using the second frequency band during the one of the second series of time allocations. This method may also transmit, to the client device and via the first frequency band and during the one of the second series of time allocations, a response to the retry of the first message. 
     Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.