Abstract:
Systems and methods to enable different types of radio communication devices to communicate using a common language in order to enable the devices to regulate their use of the spectrum. Each device participating in the ad hoc control channel (ACC) protocol transmits information using a common signal format that each of the other participant devices is capable of recognizing, in order to share information about how it uses the radio frequency band. Each device receives the information transmitted by other participant devices and based on that information, controls one or more of its operational parameters that impact usage of the radio frequency band. The ACC protocol enables devices of the same or different type to harmonize (instead of alienate) themselves with each other by allowing them to communicate about their usage of the radio frequency band using a common signaling framework. Improvement can be achieved in spectrum efficiency and ultimately provide a more reliable and enjoyable experience for the end user of a device that operates in that radio frequency band.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 60/365,776, filed Mar. 21, 2002, the entirety of which is incorporated herein by reference. 
    
    
     BACKGROUND OF INVENTION 
     Unlicensed radio spectrum, often called the unlicensed band, has been allocated in various countries to allow devices or services to use spectrum without exclusion to other devices or services. For example, in the United States, the unlicensed bands at 2.4 GHz and 5 GHz do not require a license fee, and are available to be used by any device or service, within certain power and bandwidth limits. Similar conditions hold true for unlicensed bands in other countries. However, with freedom and zero cost spectrum comes overuse. 
     Market projections indicate that use of the unlicensed bands will grow significantly. As more devices use the unlicensed bands, the spectrum will become more crowded, which in turn will degrade the quality of service. Already, in the U.S., many experts have complained that the unlicensed bands have become a “garbage dump” due both to a lack of standardization and “greedy” use of spectrum by some devices, such as the 900 MHz band where many cordless phones were designed to operate. Thus, technology is needed to exploit the benefits of the unlicensed band without degrading the level of service that users expect. 
     SUMMARY OF INVENTION 
     Briefly, systems and methods are provided to enable different types of radio communication devices to communicate using a common language called an ad-hoc control channel (ACC) protocol. Devices that participate in the ACC protocol self-regulate their use of the frequency band. In general, no single device or group of devices is responsible for managing the use of the radio frequency band by other devices. Each device participating in the ad hoc control channel (ACC) protocol transmits (e.g., broadcasts) information using a common signal format that each of the other participant devices is capable of recognizing, in order to share information about how it uses the radio frequency band. Each device receives the information transmitted by other participant devices and based on that information, controls one or more of its operational parameters that impact usage of the radio frequency band. The ACC protocol enables devices of the same or different types to harmonize (instead of alienate) themselves with each other by allowing them to communicate about their usage of the radio frequency band using a common signaling framework. Improvement can be achieved in spectrum efficiency and ultimately provide a more reliable and enjoyable experience for the end user of a device that operates in that radio frequency band. 
     The above and other objects and advantages will become more readily apparent when reference is made to the following description take in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing multiple wireless radio communication devices that operate in a shared radio frequency band and employ the ad hoc control (ACC) protocol. 
         FIG. 2  is a graphical diagram showing a spectral profile of an exemplary radio frequency band where the multiple radio communications shown in  FIG. 1  may operate. 
         FIG. 3  is a flow chart that generally illustrates the operation of the ACC protocol. 
         FIG. 4  is diagram of an exemplary beacon signal that ACC participant devices transmit to each other in order to share information about their respective use of the frequency band. 
         FIGS. 5 and 6  are timing diagrams that depict specific procedures whereby ACC participant devices transmit beacon signals. 
         FIGS. 7 and 8  are flow charts depicting procedures by which a new (nonparticipant) device joins the ACC protocol. 
         FIG. 9  is a block diagram of an exemplary baseband modulation process suitable for the ACC protocol. 
         FIGS. 10A and 10B  are block diagrams of exemplary radio transmitters suitable for transmitting ACC protocol signals. 
         FIGS. 11A and 11B  are block diagrams of receiver systems suitable for receiving ACC protocol signals. 
         FIG. 12  is a block diagram of an exemplary radio communication device that may participate in the ACC protocol. 
         FIGS. 13 and 14  are block diagrams showing alternative ways of deploying the ACC protocol technology in radio communication devices. 
     
    
    
     DETAILED DESCRIPTION 
     In an unlicensed or shared frequency band, it is inevitable that two or more of devices will be transmitting at the same time. There is, therefore, a high likelihood that they will interfere with each other. When interference occurs, a signal from one device to another may not be received properly, causing the source device to retransmit (therefore reducing throughput), or possibly entirely destroying the communication link between two communication devices. 
     Managing an unlicensed band may involve minimizing interference and maximizing spectrum efficiency. Minimizing interference is expressed in terms of signal-to-noise ratio (SNR), bit error rate (BER), etc. Maximizing spectrum efficiency is expressed as data rate per bandwidth used per area (bps/Hz/m 2)  or as a number of “satisfied” users, where satisfied is based on meeting certain performance criteria such as: data rate, latency, jitter, dropped sessions, and blocked sessions. A control protocol is useful to avoid interference when possible and to mitigate the impact of interference when it cannot be avoided. 
     Referring first to  FIGS. 1 and 2 , a plurality of wireless radio communication devices are shown that operate in a shared or unlicensed frequency band. Devices  100 ,  110 ,  120  and  130  are called “participant” devices because they are already operating in accordance with rules of an ad-hoc control channel (ACC) protocol. Device  140  is called a “non-participant” device because it may seek to access use of the frequency band, but is currently not participating in the ACC protocol. All of the devices  100 - 140  are operating in a shared radio frequency band, an example of which is the 2.4 GHz unlicensed band (in the U.S.) shown in FIG.  2 . For example, device  100  is an IEEE 802.11b device, device  110  is another IEEE 802.11b device, device  120  is a frequency hopper device of one type and device  130  is a frequency hopper device of another type. Another exemplary band is the 5 GHz UNII bands in the U.S. The new or non-participant device  140  may be, for example, another IEEE 802.11b device.  FIG. 2  shows that devices  100  and  110  and new device  140  operate on different 802.11b channels, but it should be understood that they all may operate on the same 802.11b channel. 
     The participant devices may communicate using an ACC. The ACC may be at a particular frequency channel in the radio frequency band. For example,  FIG. 2  shows that the ACC may be a narrowband channel located at a far end of the radio frequency band. Alternatively, the ACC may be created with a spreading code within a particular frequency sub-band (channel) in the radio frequency band, similar to direct sequence spread spectrum techniques used in IEEE 802.11b. In fact, the ACC may be a particular IEEE 802.11b channel. 
     Referring to  FIG. 3 , a general process  200  for the ACC protocol will be described. In step  210 , using the ACC (e.g., frequency channel, spreading code, etc.) recognized by each participant device and a common signal format also recognized and used by each participant device, the participant devices share information with each other as to how each participant device is using the frequency band. Examples of this information are described hereinafter. In step  220 , on the basis of this shared information and optionally also on the basis of spectrum policy information, each participant device controls how it uses the frequency band. In some cases and under certain conditions, a participant device may change its operational parameters as and if needed, and in other cases and under certain conditions, no changes may be necessary. When transmitting information to other participant devices, a participant device may include, in addition to its spectrum usage information, information about other activity the device detects in the band, such as at which frequencies the device detects interference from other non-participant devices. 
     In the course of sharing information among the participant devices, as shown by step  230 , a provision may be made to arbitrate which participant device has the responsibility for responding to requests from new devices. New devices may be admitted to become participant devices in step  240 , and may be assigned operational parameters to use, or may independently select which operational parameters to use based on policy information stored therein. A more complete description concerning the admission of new devices is described hereinafter in conjunction with  FIGS. 7 and 8 . 
     Each device that is capable of participating in the ACC protocol may store spectrum policy information about how it should behave with respect to other devices. 
     This policy information may be obtained or derived from a regulatory body that regulates the applicable radio frequency band or bands. For example, in the United States, the Federal Communication Commission (FCC) regulates emission (power level, bandwidths, etiquette, etc.) and other requirements that are permitted in frequency bands, including the unlicensed bands. These requirements can be used to formulate the policy information stored in a device. In addition, or alternatively, device manufacturers may agree to a basic set of policies concerning device behaviors in a frequency band, and to store information pertaining to those policies in devices that they make and sell. It is further possible to update or change policy information stored in a device already in the field in order to account for changes made by the regulatory body or association of manufacturers. 
     The policy information is useful because when a participant device receives information from other participant devices as to their usage of the frequency band, that participant device is able to make its own decision about how to behave in the frequency band, such as at what frequency to locate in the band. It may be a general spectrum policy that a participant device should attempt to avoid all other participant devices if possible. If a participant device cannot avoid all other participant devices, it can request a participant device to move or change how it uses the frequency band. When a participant device receives a request to move or change its behavior, it should honor the request if possible. In a highly-used space, the ACC protocol may enforce a limit on how often a device can change parameters. 
     If access can still not be obtained by a participant device, several options may be available: 
     1. Notify the user of the participant device to deal with the situation. 
     2. Set usage prioritization among devices and allocate usage according to priority. 
     3. Attempt to make a determination as to which participant device the interference is least likely to affect based on parameters such as signal strength. 
     One example of a usage prioritization is based on traffic type. Devices that communicate a certain type of traffic, such as video, may have a higher priority entitlement to the frequency band, over devices that communicate another type of traffic, such as voice or audio. Usage prioritization could also be based on communication protocol. Whatever the basis for prioritization, if a conflict regarding access to or use of the band arises between any two devices, the higher priority device will prevail. If there is a conflict between devices having the same priority, one solution would be to give one device priority for a certain period of time, then switch priority to the other device. Another solution is to allocate usage based on a first-come, first-serve basis. This usage prioritization information would be stored as policy information in each device, and may be updated from time-to-time across all participant devices. 
     One manner in which participant devices may share information with each other is through the use of beacon signals.  FIG. 1  shows that each participant device transmits a beacon signal.  FIGS. 4-6  show an exemplary beacon signal and one mechanism for sharing information about participant devices. 
     Referring to  FIG. 4 , an exemplary ACC beacon signal will be described. A participant device broadcasts an ACC beacon signal every N seconds, for example, in a common format, such as that shown in FIG.  4 . The ACC beacon signal is intended to be received by any device that is capable of receiving and decoding ACC beacon signals. The beacon signal may include a header (H) and several fields (F 1  through F 6 , for example) that include information such as: the frequency (or frequencies) the device is using, the power level it transmits at, the traffic type it is generating (e.g., voice, data, video, audio, etc.), the communication protocol type it uses to communicate the traffic to other devices (e.g., IEEE 802.11b, Bluetooth™, etc.), the frequency hopping pattern it uses (if applicable), the frequency bandwidth it occupies, its data rate and a device type (e.g., set-top box, hand-held unit, etc.). If the device is a frequency hopping device, it may include in its beacon signal the hop duration, hop bandwidth, hop timing as well as the frequency hopping sequence. The beacon signal may also include a field that requests another participant device to change its frequency, power level, etc. Further still, the ACC beacon signal may include a request message from a device seeking to become a participant device as described hereinafter in conjunction with FIG.  8 . 
     Each participant device can transmit its beacon signal periodically as shown in  FIG. 5 , or otherwise on an occasional or aperiodic basis. Other participant devices will detect and decode the beacon signals and gain knowledge about how that device uses the spectrum. For example, participant device  100  transmits its beacon signal B 1  periodically with period P 1 , participant device  110  transmits its beacon signal B 2  with period P 2 , etc. This may be suitable for some applications. 
     To facilitate low power operation for participant devices, it may be desirable that a participant device wake up and hear all the relevant beacon signals during one power-up interval. One way to achieve this is shown in  FIG. 6. A  beacon interval may begin with a “lead beacon” (LB) followed by the other beacons. For example, when a participant device powers-up from a sleep or low power mode, it may listen for a beacon interval to detect a lead beacon. If it does not detect a lead beacon, it becomes a “beacon leader” and transmits a lead beacon every N seconds. For example, in  FIG. 6 , participant device  110  is a beacon leader and transmits its beacon B 2  as the lead beacon. On the other hand, if a participant device comes up and detects a beacon, it joins at the end of the train of beacons that follow the lead beacon. An arbitration scheme such as carrier-sense multiple-access (CSMA) is used to arbitrate access to the end of the beacon train. Since collisions can occur, the beacon leader generates acknowledgment (A) packets to accept the new trailing beacon signals. Each participant device remembers its position in the beacon train by counting all of the beacons and/or acknowledgments that preceded it, so arbitration only occurs once. It is possible that a participant device may hear multiple beacon trains, for example, if it is near two groups of participant devices. In this case, that particular participant device will join both groups. 
     A participant device may choose to terminate its participation. In the orderly case, a participant device may include in a beacon signal information to indicate to the other participant devices that it is terminating. In some cases, a participant device will terminate without notice. The participant that is next in the beacon train transmits its beacon signal after a timeout interval, and updates its place in the beacon train. If the beacon leader terminates, the next participant in line takes over its place as leader. 
     In an IEEE 802.11 WLAN, it may be redundant for every station (STA) to declare itself as a participant to the ACC protocol. To reduce overhead, the access point (AP) could participate on behalf of the entire WLAN. One drawback of this is that the interference profile or other spectrum activity of STAs at the edge of the WLAN might be different than at the AP. 
     The ACC beacon signals are designed to be heard even with a low signal level. If a first device would tend to cause interference problems with a second device, the second device should hear the ACC beacon sent by the first device. There may be some cases when a first device can detect the beacon of a second device, but the second device is not strong enough to cause interference. In this respect, honoring all beacon signals from another device may be taken as the conservative approach. 
     There are some enhancements to the basic beacon mechanism described above. One enhancement involves transmitting in a beacon signal information to indicate the transmit power level of the normal signal that a participant device transmits with, and the transmit power of the beacon signal itself. When another device receives that beacon signal, it can examine the actual received power level of the beacon and compare it with the information included in the beacon signal in order to estimate the loss of the channel between the two devices. That receiving device can also calculate how strong the normal signals from the participant device will be, and determine if it wants to honor it or not. 
     Another enhancement is one in which in its beacon signal, a first participant device requests a sample transmission from a second participant device to occur at a designated time. The first participant device measures the sample signal to see if it actually causes an interference problem with it. The first participant device can then decide whether the second device should be considered as an interferer and therefore honor its spectrum usage information. 
     It is desirable to make the components to implement the ACC protocol in each device as simple as possible regardless of the type of device in which it is employed. 
     By simplifying its implementation, deployment can be made cost effective in a wide range of devices. The baseband modulation format and the radio frequency transmission method may be chosen so that they can be implemented with existing radio hardware and with existing or minimal additional firmware and/or software in devices already planned for deployment in a particular application. However, solutions are also described hereinafter to provide the ACC protocol technology in a “retrofitting” manner to devices, as an add-on module. 
       FIGS. 7 and 8  are flow charts that depict two ways that a non-participant device may join the ACC protocol and become a participant device.  FIG. 7  shows a process  400  in which a new (non-participant) device accesses the ACC protocol by first, in step  410 , listening for beacon signals from participant devices, and then in step  420 , learning where and/or at what time intervals spectrum is available and begins operation in the spectrum using parameters based on information gathered from the beacon signals. That device will transmit a beacon signal to share information with the other participant devices about its spectrum usage characteristics. 
     In  FIG. 8 , a process  500  is shown in which the ACC protocol supports, in addition to the beacon signal, a request signal and a response signal (shown also in  FIG. 1  between device  110  and device  140 ). In step  510 , a new (non-participant) device broadcasts a request message on the ACC intended for reception by any participant device. The request message is sent using modulation parameters common to the ACC protocol. For example, the request message may be an ACC beacon signal having a field containing data for requesting access to the spectrum, as shown in FIG.  1 . In step  520 , a participant device (that has been assigned responsibility for handling request messages for a current time interval) receives the request message and transmits a response message to the requesting device. As an example, the participant device that is the beacon leader may respond to the request message. The response message may contain any one or more of the following information: 
     Number of Participant Devices; 
     Number and kind of each communication protocol active in the frequency band (e.g., IEEE 802.11g, Bluetooth™, cordless1, IEEE 802.11a, IEEE 802.11b, etc.); 
     Priority information for QoS (e.g., cordless needs 2.42-2.43 MHz for voice, rest is for data); 
     “Bad” frequencies known to contain interference; 
     Measured duty cycles at various frequencies; 
     High-level services supported and on which protocol (e.g., remote control protocol using 802.15.4 on channel 5); and 
     Security information and permissions. 
     In addition, if the request message contains a request for access to the frequency band, the response message may include a channel assignment as well as other restrictions on the device to account for the other participant devices already active in the frequency band. The channel assignment may be made using the following information from each participating device, as well as the new participant: (1) spectrum map of received signal strength indicator (RSSI) and duty cycle vs. frequency; (2) transmit power; (3) transmit bandwidth, and (4) current consumption requirements. When a device terminates its participation in the ACC protocol or joins the ACC protocol, one or multiple devices may change their channel allocations in order to optimize the use of the spectrum. 
     There may be a policy for deciding how often a participant device is required to respond to request messages based on its sensitivity to power consumption. In some cases it may make sense to assign ownership to one participant device (e.g., set-top box, AP, or a special gateway device) in order to minimize power consumption for other battery-powered participant devices. However, the ACC protocol generally operates as a distributed protocol. Since the policy decisions are jointly owned by all participants, there need not be a notion of a network “master.” 
       FIG. 9  shows an example of an ACC baseband modulation process  300  (forming a part of an ACC modem). A framing block  302  frames raw ACC data bits (supplied by a processor) in accordance with predefined word and field size parameters (for, e.g., beacon signals, request signals, response signals, etc.). A forward error correcting (FEC) block  304  follows the framing block to add FEC to the framed data. A cyclic redundancy code (CRC) block  306  follows the FEC block  304  to add redundancy codes. A first-in first-out (FIFO) buffer  310  receives the output of the CRC block  306  which supplies buffered data to a latch  312  driven by a clock signal. Data is clocked out from the latch  312 . All of the blocks for the baseband modulation process  300  may be implemented in software or firmware (gates), or blocks  302 ,  304  and  306  may be implemented in software and blocks  310  and  312  may be implemented in firmware. The output of the ACC baseband modulation process  300  is an ACC baseband signal to be transmitted. A complementary ACC baseband demodulation process is shown at reference numeral  352  in  FIGS. 11A and 11B . 
       FIGS. 10A and 10B  show examples of radio transmitters that may be useful to upconvert the output of the baseband modulation process  300  to RF.  FIG. 10A  shows an example of a frequency shift keying (FSK) transmitter  320 . The output of the baseband modulation process  300  is converted to an analog signal by an analog-to-digital converter {not shown) and the analog signal is coupled as input to a low pass filter (LPF)  322 . The output of the LPF  322  is coupled to an oscillator  324  that is driven to oscillate at a radio frequency (e.g., the radio frequency associated with the control channel in the far upper end of the radio frequency band) controlled by a synthesizer  326 . Omitted for the sake of simplicity is a digital-to-analog converter to convert the digital ACC baseband signal to an analog signal prior to the LPF  322 . 
     Another example shown in  FIG. 10B  is an ON/OFF keying (OOK) transmitter  330 . In this transmitter, a synthesizer  332  drives an oscillator  334  to oscillate at a carrier frequency. The output of the oscillator  334  is coupled to a power amplifier (PA)  336  that amplifies the signal for transmission via an antenna  338 . The output of the baseband modulation process  300  is used to key ON and OFF the power amplifier  336 , where ON may designate a “1” and OFF may designate a “0.” In this manner, the digital information output by the modulation process is modulated onto the oscillator signal at a frequency controlled by the synthesizer  332 . 
     An advantage of the transmitters shown in  FIGS. 10A and 10B  is that they use many components already in most radio transceivers, such as the synthesizer, oscillator and power amplifier. 
       FIGS. 11A and 11B  illustrate examples of receiver systems (for RF downconversion and baseband demodulation) that can be used to receive OOK and FSK signals, respectively, and recover the ACC data.  FIG. 11A  shows a receiver system  340  comprising a radio receiver  342  coupled to an antenna  341  and consisting of a low noise amplifier (LNA)  344 , an RF downmixer  346 , an oscillator  347 , a synthesizer  348  and an LPF  349 . The output of the LPF  349  is an analog signal that is coupled to a detector  350  which resolves the two states of the OOK modulated signal. The demod block  352  performs the baseband demodulation to undue the modulation and framing processes shown in FIG.  9 . The output of the demod block  352  is the raw ACC data that can be processed by a processor. 
     In  FIG. 11B , the receiver system  360  comprises the radio receiver  340  coupled to antenna  361 , an LPF  362 , a discriminator  364  and a detector  366 . The discriminator  364  and detector  366  process the output of the LPF  362  to recover the FSK data. A demod block  352  recovers the raw ACC data from the signal at the output of the detector  366 . The receiver hardware and decision firmware for the OOK and FSK receivers are simple to implement, and in many cases use existing radio hardware in the device. An ACC modem may be formed by the ACC baseband modulation blocks shown  FIG. 9  together with the post-RF processing elements and the demod block  352  shown in  FIGS. 11A  or FIG.  11 B. 
     Turning to  FIG. 12 , an exemplary radio communication device  600  is shown and depicts one way in which the ACC protocol technology may be deployed in a device to enable it to become a participant device. The device  600  comprises a radio transceiver  610  that transmits and receives signals via at least one antenna  620 . The characteristics of the radio transceiver  610  may vary among specific participant devices, but it nevertheless will support the ability to transmit and receive ACC protocol signals in the radio frequency band of interest. The radio transceiver  610  downconverts a receive signal to a baseband signal that is coupled to a baseband processing section  630  via an analog-to-digital converter (ADC)  640 . Conversely, the radio transceiver  610  upconverts a baseband signal supplied by the baseband processing section  630  via a digital-to-analog converter (DAC)  645  for transmission via the antenna  620 . The radio transceiver  610  would either already include the necessary components to perform the types of upconversion and downconversion described in conjunction with  FIGS. 10A ,  10 B,  11 A and  11 B, or will include them as additional components. 
     The baseband section  630  includes a modem  632  that performs the baseband modulation and demodulation required to transmit and receive traffic data according the communication protocol that the device supports, such as, for example, the IEEE 802.11x protocols, the Bluetooth™ protocol, IEEE 802.15.4, etc. In addition the baseband section  630  includes an ACC modem  634  that performs the baseband modulation and demodulation to perform the signal formatting (and de-formatting) of spectrum usage data in accordance with the ACC protocol, examples of which are described above in conjunction with  FIGS. 9 ,  11 A and  11 B. The baseband section  630  may be implemented in an application specific integrated circuit (ASIC) with a plurality of digital logic gates. Alternatively, many or all of the functions of the baseband section  630  may be performed by software executed by a processor, such as processor  650  or processor  660 , described further hereinafter. The modems  632  and  634  may be integrated into one modem block. 
     Higher level logic may be performed by an on-board or embedded processor  650 . Instructions executed by the processor  650  to perform the ACC protocol signal generation and device control processes described above may be stored in an on-board memory  655 . For example, spectrum policy information and ACC protocol control logic may be stored in the memory  655 . As an alternative or in addition to the embedded processor  650  and memory  655 , a host processor  660  may be coupled to the baseband section  630  via an interface  670 . The host processor  660  will likewise execute instructions stored in a memory  665  that may include the spectrum policy data and ACC protocol control logic. The host device may be a computer (laptop or desktop), PDA, set-top box, infant monitor, cordless phone, cellular phone, remote control, television, stereo equipment, or any other device that uses wireless communication in a shared radio frequency band. 
       FIGS. 13 and 14  illustrate examples of other possible deployments of the ACC protocol technology. In  FIG. 13 , an ACC module  700  is provided that is a stand-alone module dedicated to supporting the ACC protocol technology in order to supplement the functionality of a host radio communication device that cannot otherwise be altered or enhanced to execute the ACC protocol technology. The ACC module  700  comprises a radio transceiver  710 , an ACC modem  720  (e.g., an ASIC), a processor  730  and a memory  740 . The components of the ACC module  700  are designed to be dedicated solely or primarily to implementing the ACC control protocol procedures. The radio transceiver  710  is a simple transceiver that performs the necessary upconversion/downconversion to transmit and receive ACC protocol signals, examples of which are shown in  FIGS. 10A ,  10 B,  11 A and  11 B. The ACC modem  720  is similar to the ACC modem  634  shown in  FIG. 12 , and executes the baseband modulation and demodulation of the ACC protocol signals (e.g., beacon signals, request signals, response signals, etc.). The processor  730  performs the higher level processing and ACC control. The memory  740  stores the higher level ACC control programs executed by the processor  730  as well as spectrum policy information also used by the processor  730 . The ACC module  700  supplies over an interface  750  control signals to a host radio communication device  800  comprising a host processor  810 , a host baseband modem  820  and a host radio transceiver  830 . An example of an interface  750  is serial data interface, such as a universal serial bus (USB). The ACC module  700  and the host device  800  would have the necessary hardware and/or software needed to implement the interface  750 . The control signals the ACC module supplies to the host device  800  direct the host processor  810  as to how to control use of the spectrum (frequency assignment, power level, bandwidth control, etc.). The components of the host device  800  are dedicated to the communication protocol(s) and applications it supports, while the ACC module  700  may be designed to provide the ACC protocol communication and control functions. The deployment format shown in  FIG. 13  is suitable when the host device cannot or does not have the flexibility to support any of the ACC control functions, and the radio transceiver  830  of the host device is not capable of upconverting and downconverting the ACC protocol signals. 
       FIG. 14  shows an example of a deployment format wherein the host device  800  has a host radio transceiver  830  that is capable of upconverting and downconverting the ACC protocol signals, but not the baseband and higher level processing. The ACC module  700 ′ is similar to ACC module  700  except that it does not include a dedicated radio transceiver. The ACC modem  720  is coupled to an interface circuit  755  that interfaces signals between the ACC modem  720  and the host radio transceiver  830 . 
     For example, the interface circuit  755  is a multiplexer that couples analog or digital baseband ACC signals to be transmitted to the host radio transceiver  830  and couples the received baseband ACC signals to the ACC modem  720  from the host radio transceiver  830 . The host processor  810  also will receive via an interface  750  (similar to the one described above in conjunction with  FIG. 13 ) the control signals generated by the processor  730  that determine how the host radio communication device  800  uses the radio frequency band. 
     There are many useful applications of the ACC protocol technology. One example is a set-top device. For example, a set-top box (capable of acting as a participant device) would announce itself and its capabilities including communication protocol type (e.g., IEEE 802.11a, Bluetooth™, IEEE 802.15.4), wireless service it supports (e.g., WAN data, VoIP over 802.11a, video over 802.11a, remote control via Bluetooth™ or 802.15.4), and receiving similar information from other participant devices (e.g., receive information from remote controls, video juke boxes, stereo, cordless VoIP phones, etc.). 
     The set-top box would determine where neighboring homes are deploying their WLAN/WPAN channels and locate itself in the best location in the spectrum for a new channel(s). This may require other participant devices to change frequencies in order to optimize spectral efficiency and capacity/interference. The set-top box may also learn, from information shared by other participant devices, where there is interference (due to microwaves, radars, or non-ACC devices) in the band and make a note to stay away from them. The set-top box device can then begin deployment of the desired protocol(s) and create connections with other devices (e.g., VoIP phones, laptops, televisions, etc.). 
     Other examples of applications of the ACC protocol technology are televisions that announce their capability and determine what other devices are active in a home, and make a wireless connection with video juke boxes, set-top boxes, remote controls, etc. The ACC protocol technology may have utility in stereo equipment, vending machines, cordless telephones, cellular telephones, still and video cameras, remote controls, lights/appliances, and personal digital assistants. For example, a cellular telephone may locate where Bluetooth™ or voice-over IP (VoIP) IEEE 802.11x is supported for a user ID in order to obtain a cellular-to-WLAN handoff. A PDA may determine that a user&#39;s favorite news service is supported, on a wireless channel supported by a certain communication protocol, and immediately join the network to receive information on that service. Still another example is a frequency band where multiple cellular telephone devices may obtain VoIP IEEE 802.11x service in the presence of other IEEE 802.11x devices as well as non-IEEE 802.11x frequency hopping cordless phone devices. 
     The ACC protocol concepts can be made a part of communication protocols for devices that operate in a shared radio frequency band. For example, the IEEE 802.11x protocols may include the ACC protocol and another communication protocol, such as Bluetooth™, IEEE 802.15.4 or any future protocol or standard may include the ACC protocol. In this way, devices that operate in accordance with these different standards will automatically include the intelligence to cooperate with devices of other communication standards in using the shared frequency band or bands. 
     In sum, a method is provided for sharing use of a radio frequency band by a plurality of devices that may operate with different communication protocols, the method comprising sharing information among the devices using a common signaling format so that the devices may self-regulate their use of the radio frequency band. Each device may control one or more of its operational parameters based on knowledge about how the other devices are using the frequency band. 
     From the perspective of a device operating in the frequency band, a method is provided for operating a radio communication device that operates in a radio frequency band shared with a plurality of other radio communication devices. The method comprises generating a signal for transmission from the first radio communication device to be received by the plurality of other radio communication devices, wherein the signal contains information describing how the first radio communication device uses the radio frequency band. 
     Still further, a combination is provided comprising a modem that generates a baseband signal for radio transmission and recovers a baseband signal from a received radio signal, and a control processor coupled to the modem that supplies data for transmission to the modem and processes data recovered from a received radio signal by the modem. The control processor generates spectrum usage data coupled to the modem to be formatted for transmission to other radio communication devices operating in a radio frequency band, wherein the spectrum usage data comprises information describing how a radio communication device associated with the modem and control processor uses the radio frequency band. Furthermore, the control processor processes received spectrum usage data derived from a received baseband signal that describes how at least one other radio communication device uses the radio frequency band, and wherein the control processor generates control signals to control one or more operational parameters of the radio communication device that impact usage of the radio frequency band based on the received spectrum usage data. This combination may be coupled to a host radio communication device in order to supplement its functionality to comply with the ACC protocol. 
     Yet further, a processor readable medium is provided which is encoded with instructions that, when executed by a processor, cause the processor to perform a step of generating a signal for transmission from a first radio communication device to be received by a plurality of other radio communication devices, wherein the signal contains information describing how the first radio communication device uses a radio frequency band in which it operates. 
     The above description is intended by way of example only.