WO2009056899A1

WO2009056899A1 - Channel change decision based on connection priority

Info

Publication number: WO2009056899A1
Application number: PCT/IB2007/003332
Authority: WO
Inventors: Christian Zechlin; Thomas Block
Original assignee: Nokia Inc
Current assignee: Nokia Inc
Priority date: 2007-11-02
Filing date: 2007-11-02
Publication date: 2009-05-07
Anticipated expiration: 2010-05-02

Abstract

A method, apparatus, and computer program product are disclosed for wireless communications networks, such as WiMedia networks, to solve problems of unnecessary delay when a channel change request is forwarded to the device host side from the UWB PHY chip. A wireless communications device selects a channel finding technique in a first stage, based on whether the device has any active connections in a current channel. The device receives channel change priorities from its host, assigning priorities for various existing connections. In accordance with at least one embodiment, the device may receive the channel change priorities at any time prior to when a determination needs to be made based on the priorities. The device then performs the selected channel finding technique with a plurality of channels to find a candidate channel. The initiating device determines, based on the priorities of the existing connections, whether a channel change is prioritized without involving the host in the determination. If it is determined that the channel change is prioritized, then the initiating device sends a request to at least one remote device to change its channel from the current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval. If the request is successful, the initiating device receives an acceptance of the request from the remote device. Then in a second stage, the initiating device selects a channel changing technique based on whether the device has any active connections in the current channel. If it is determined that the channel change is prioritized, then the initiating device executes the selected channel changing technique to change a channel from the current channel to the candidate channel, thereby establishing the desired new connection across the candidate channel with the remote device.

Description

CHANNEL CHANGE DECISION BASED ON CONNECTION PRIORITY

FIELD

[0001] The technical field relates to wireless communications. More particularly, the technical field relates to techniques for sharing wireless communications media in wireless network environments.

BACKGROUND

[0002] Short-range wireless proximity networks typically involve devices that have a communications range of one hundred meters or less. To provide communications over long distances, these proximity networks often interface with other networks. For example, short- range networks may interface with cellular networks, wireline telecommunications networks, and the Internet.

[0003] High rate physical layer (PHY) techniques for short-range proximity networks are quickly emerging. One such technique involves frequency hopping applications of orthogonal frequency division multiplexing (OFDM). This technique involves the transmission of OFDM symbols at various frequencies according to pre-defined codes, such as Time Frequency Codes (TFCs). Time Frequency Codes can be used to spread interleaved information bits across a larger frequency band. The WiMedia Ultra- Wideband (UWB) Common Radio Platform incorporates media access control (MAC) layer and physical (PHY) layer specifications based on Multi-band Orthogonal Frequency Division Multiplexing (MB- OFDM). The WiMedia UWB enables short-range multimedia file transfers at high data rates with low power consumption, and operates in the 3.1 to 10.6 GHz UWB spectrum.

[0004] The WiMedia Alliance has developed an OFDM physical layer. This physical layer is described in WiMedia Alliance MultiBand OFDM Physical Layer Specification, Release 1.1, January 14, 2005 (also referred to herein as the WiMedia PHY. This document is incorporated herein by reference in its entirety.

[0005] The WiMedia Medium Access Control (MAC) group is developing a MAC layer that would be used with an OFDM physical layer, such as the WiMedia PHY. A

i current version of this MAC is described in O'Conor, Jay; Brown, Ron (ed.), Distributed Medium Access Control (MAC) for Wireless Networks, WiMedia Technical Specification, Release 1.2, (also referred to herein as the WiMedia MAC Specification v. 1.2). This document is incorporated herein by reference in its entirety.

[0006] This MAC layer involves a group (referred to as a beacon group) of wireless communications devices that are capable of communicating with each other. The timing of beacon groups is based on a repeating pattern of "superframes" in which the devices may be allocated communications resources. These communications resources may be in the form of one or more time slots, referred to as media access slots (MASs).

[0007] MAC layers govern the exchange among devices of transmissions called frames. A MAC frame may have various portions. Examples of such portions include frame headers and frame bodies. A frame body includes a payload containing data associated with higher protocol layers, such as user applications. Examples of such user applications include web browsers, e-mail applications, messaging applications, and the like.

[0008] In addition, MAC layers govern the allocation of resources. For instance, each device requires an allocated portion of the available communication bandwidth to transmit frames. The WiMedia MAC provides for the allocation of resources to be performed through communications referred to as beacons. Beacons are transmissions that devices use to convey non-payload information. Each device in a beacon group is assigned a portion of bandwidth to transmit beacons.

[0009] Such transmissions allow the WiMedia MAC to operate according to a distributed control approach, in which multiple devices share MAC layer responsibilities. Accordingly, the WiMedia MAC Specification v. 1.2 provides various channel access mechanisms that allow devices to allocate portions of the transmission medium for communications traffic. These mechanisms include a protocol called the distributed reservation protocol (DRP) in which reservations for connections are negotiated among devices. These mechanisms also include a protocol called prioritized contention access (PCA).

[0010] The WiMedia PHY provides for various channels across a frequency range.

These channels are referred to as logical channels. Each logical channel employs a different Time Frequency Code (TFC). As discussed above, TFCs specify a repeating time sequence in which various frequency bands within a frequency range are used. Thus, a device employing a TFC transmits at different frequencies at particular times specified by the TFC. Currently, the WiMedia PHY specifies each band having a 528 MHz bandwidth. Also, these bands are within a frequency operating range of between 3.1 and 10.6 GHz.

[0011] If a WiMedia MAC device decides to change or re-select a beacon group channel, it can send a Channel Change IE notice in its beacon to inform the other devices of that beacon group. Many situations can occur in which a channel change is desirable (for either a device or to a group of devices). One such situation occurs when a currently used channel (i.e. a beacon group) is congested. This congested condition may be attributed to a large number of devices in the beacon group and/or to a lack of available resources for a new application or DRP reservation. Other situations in which a channel change is desirable to occur is when radio conditions for the current channel are poor (e.g. interference, frame error rate, etc.), the achievable range on the current radio channel is insufficient, and/or a specific device is found operating on another channel.

[0012] A problem in the art is that in channel change situations, the UWB PHY device that has been requested to make a channel change by an external host device or a link owner device needs to respond to the channel change request quickly. However, if the channel change request is forwarded to the device host side from the UWB PHY chip, unnecessary delay is created that can result in degrading channel change performance.

[0013] The existing WiMedia MAC Specification provides that a device initiating a channel change will send a ChannelChange IE containing a ChannelChangeIECount which tells when the Channel Change will happen. The start value for the ChannelChangeIECount can be 255 at most, meaning 255 * 65ms = 16 seconds. However, the WiMedia MAC Specification does not define any minimum start value for the counter; it could be as short as 130ms. Next, the WiMedia MAC Specification states: "On reception of a Channel Change IE, a device that also intends to change channels in a coordinated manner should include a Channel Change IE with the same fields in its beacon." This means that a device initiating a Channel Change will assume that a remote device will not follow if the remote device did not include the same ChannelChange IE in its beacon. Thus, a device receiving a ChannelChange IE must react fast to reply with its own ChannelChange IE, indicating: "Yes, I agree with this Channel Change". A problem in the art is that the physical transceiver chip that receives a ChannelChange IE would have to ask its Host each time whether or not a channel change is allowed. This means (assuming e.g. a ChannelChangeIECount start value of 130ms) that the Host needs to return an acknowledgement within 65ms, otherwise there is no chance to add its own ChannelChange IE in the next beacon to be transmitted.

SUMMARY

[0014] The problems of unnecessary delay when a channel change request is forwarded to the device host side from the UWB PHY chip are overcome by the embodiments disclosed herein.

[0015] In an example embodiment, the UWB PHY chip makes a channel change decision based on priority information that has been provided to the UWB PHY chip by the host using an API that the host uses for assigning priorities for various existing connections. API primitives enable the host to provide the necessary information to the UWB PHY chip. The UWB PHY chips include logic to maintain the priority information and to appropriately react to various events based on the available priority information.

[0016] In an example embodiment, a wireless communications device selects a channel finding technique in a first stage, based on whether the device has any active connections in a current channel. The device receives channel change priorities from its host, assigning priorities for various existing connections. The device then performs the selected channel finding technique with a plurality of channels to find a candidate channel. The device then determines based on the priorities of the existing connections whether a channel change is prioritized without involving the hosting entity in the determination. If the determination indicates that the channel change is prioritized, then the device sends a request to at least one remote device to change its channel from the current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval. If the request is successful, the initiating device receives an acceptance of the request from the remote device. Then in a second stage, the initiating device selects a channel changing technique based on whether the device has any active connections in the current channel. If it is determined that the channel change is prioritized, then the initiating device executes the selected channel changing technique to change a channel from the current channel to the candidate channel, thereby establishing the desired new connection across the candidate channel with the remote device. [0017] In another exemplary embodiment, a transceiver module comprises a wireless interface configured for exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices, an interface configured for coupling the transceiver module with a local hosting entity configured for receiving channel change priorities assigning priorities for the existing wireless connections from the hosting entity and a controller configured for determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

[0018] In yet another exemplary embodiment, a chipset comprises at least one radio part and an antenna configured for exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices, one or more data buses coupling the chipset with a local hosting entity configured for receiving channel change priorities assigning priorities for the existing wireless connections from the hosting entity and a controller configured for determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

[0019] In this manner, the resulting embodiments solve problems of unnecessary delay when a channel change request is forwarded to the device host side from the UWB PHY chip.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number. The embodiments will be described with reference to the accompanying drawings, wherein:

[0021] FIG. 1 is a diagram of an exemplary operational environment;

[0022] FIGs. 2A and 2B are diagrams of superframe formats employed in shared transmission media; [0023] FIG. 3 A is a flowchart of a channel changing process executed by an initiating device according to at least one embodiment;

[0024] FIG. 3B is a more detailed flowchart of an exemplary channel changing process executed by an initiating device, according to at least one embodiment;

[0025] FIG. 3 C is a flow chart of a channel changing process executed by a remote device according to at least one embodiment;

[0026] FIGs. 4-6 are diagrams involving the format of a Distributed Reservation

Protocol Information Element;

[0027] FIG. 7 is a diagram of a device architecture, according to at least one embodiment;

[0028] FIG. 8 is a diagram of a wireless communications device implementation, according to at least one embodiment;

[0029] FIG. 9 A is a diagram of a new Unavailability Information Element according to at least one embodiment;

[0030] Fig. 9B is a flow diagram of the channel finding technique using the

Unavailability Information Element according to at least one embodiment;

[0031] FIG. 1 OA is a diagram of a modified Channel Change Information Element according to at least one embodiment;

[0032] Fig. 1 OB is a flow diagram of the channel changing technique using the modified Channel Change Information Element according to at least one embodiment;

[0033] FIG. 11 is a diagram of a new Channel Change Request Information Element according to at least one embodiment;

[0034] FIG. 12 is a diagram of a new Channel Change Response Information Element according to at least one embodiment;

[0035] FIG. 13 is a diagram of a Command Frame definition for Channel Change

Request and Response according to at least one embodiment; and

[0036] FIG. 14 is a diagram of a Channel Change Command Frame Type encoding according to at least one embodiment. [0037] FIG. 15 illustrates an exemplary software architecture according to at least one embodiment.

[0038] FIG. 16 is an example message sequence diagram for Channel Change according to at least one embodiment.

[0039] FIG. 17 is an example message sequence diagram for getting the remote device to change to the current active channel according to at least one embodiment.

[0040] FIG. 18A-18E illustrate exemplary channel change decision making scenarios.

[0041] FIG. 19 is a diagram of a transceiver according to at least one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

I. Operational Environment

[0042] FIG. 1 is a diagram of a communications environment in which the techniques of the embodiments may be employed. This environment includes a beacon group 100 in which multiple communications devices (DEVs) 102 may exchange wireless transmissions. In particular, FIG. 1 shows a device 102a sending a wireless transmission 120 to a device 102b. Also, FIG. 1 shows a device 102d sending a wireless transmission 122 to a device 102c.

[0043] Transmissions 120 and 122 are shown as being point-to-point communications. However, each of devices 102 periodically sends a transmission referred to as a beacon, which is directed (broadcast) to each device in beacon group 100. For instance, FIG. 1 shows device 102a transmitting a beacon 124, device 102b transmitting a beacon 126, device 102c transmitting a beacon 128 and device 102d transmitting beacon 125. Beacon transmissions are described in greater detail below.

II. Superframe

[0044] Wireless network transmissions in the environment of FIG. 1 , such as beacons and data communications may be based on a repeating time interval, such as a superframe. An exemplary superframe format is shown in FIG. 2A. In particular, FIG. 2A shows a frame format having superframes 202a, 202b, and 202c.

[0045] Each superframe 202 includes a beacon period 204 and a data transfer period

206. Beacon periods 204 convey transmissions from each of the active devices in the beaconing group. Accordingly, each beacon period 204 includes multiple beacon slots 207. Slots 207 each correspond to a particular device in the network. The devices employing beacon slots 207 are referred to as a beaconing group. During these slots, the corresponding device may transmit various overhead or networking information. For WiMedia networks, such information may be in predetermined forms called Information Elements (IEs).

[0046] For instance, such information may be used to set resource allocations and to communicate management information for the beaconing group. In addition, according to the present embodiment, data transfer periods 206 may be used to transmit information regarding services and features (e.g., information services, applications, games, topologies, rates, security features, etc.) of devices within the beaconing group. The transmission of such information in beacon periods 204 may be in response to requests from other devices.

[0047] Data transfer period 206 is used for devices to communicate data according to various transmission schemes. These schemes may include, for example, frequency hopping techniques that employ OFDM and/or time frequency codes (TFCs). For instance, data transfer periods 206 may support data communications across links 120 and 122. In addition, devices (e.g., DEVs 102a-d) may use data transfer periods 206 to transmit control information, such as request messages to other devices. The current WiMedia MAC provides for command and control frames for the transfer of such information. To facilitate the transmission of traffic, each device may be allocated one or more particular time slots within each data transfer period 206. In the context of the WiMedia MAC, these time slots are referred to as media access slots (MASs).

[0048] A MAS is a period of time within data transfer period 206 in which two or more devices can exchange data (i.e., communicate). According to the WiMedia MAC, MASs may be allocated among devices within the beacon group by a dedicated reservation protocol, called the distributed reservation protocol (DRP). DRP protects the MASs from contention access by devices acknowledging the reservation. Alternatively, the WiMedia MAC provides for resource allocation according to a prioritized contention access (PCA) protocol. Unlike DRP, PCA isn't constrained to reserving one or more entire MASs. Instead, PCA can be used to allocate any part of the superframe that is not reserved for beaconing or DRP reservations.

[0049] FIG. 2B is a diagram of an exemplary frame format designated by the

WiMedia MAC Specification v. 1.2. Like the frame format of FIG. 2 A, the WiMedia frame format has successive superframes 210. As shown in FIG. 2B, the current WiMedia superframe includes 256 MASs and has duration of 65,536 microseconds. Within each WiMedia superframe 210, a first set of MAS(s) is designated as a beaconing period 212. The number of MASs in this period is flexible, so it may dynamically change. The remaining portion of the (i.e., non-beaconing period portion) of WiMedia superframe 210 is designated as a data transfer period 214.

III. Channel Change Overview

[0050] The present embodiment provides techniques for a device to find best available channel for its needs. Such a channel may be found when the device has already joined a beacon group (and has thus selected a channel). Also, this may occur when the device has connection(s) or other active data transmission(s) with one or more other devices. Embodiments involve procedures for finding the best available channel as fast as possible.

[0051] If the device has already joined a beacon group, finding the best available channel involves scanning the other channels and possibly scanning for other devices. However, given the current WiMedia PHY and WiMedia MAC, such scanning is difficult after joining a beacon group on a specific channel. Also, if a device has connections with one or more other devices, it is desirable for the device to find a new channel that meets its needs without losing its existing connections. In addition, it is desirable for the device to ensure that the other device(s) will follow it into the new channel (or at least know which devices are willing to follow it into the new channel)

[0052] The current WiMedia PHY and WiMedia MAC provide no mechanisms for such channel changes. Thus, the present embodiment provides solutions for finding a new channel candidate, sharing channel change related information, and executing a channel change. Accordingly, FIG. 3 A is a flowchart of an exemplary channel changing process executed by an initiating device, according to at least one embodiment. [0053] The process of FIG. 3 A includes a step 300 in which a device establishes a connection to a beacon group. In step 302 the device finds one or more channel candidates. Step 302 may employ different techniques based on various factors. For instance, certain techniques may be employed when the device has no active connections (e.g., DRP reservations), but may have active PCA data transmissions in the current channel, while other techniques may be employed when the device has one or more active connections (e.g. DRP reservations) in the current channel. In accordance with at least one embodiment, the device may continually search for channel candidates before or during a connection or alternatively, may search for channel candidates only on demand.

[0054] In a step 304, the device receives channel change priorities from its local host, assigning priorities for various existing connections. In accordance with at least one embodiment, the device may receive the channel change priorities at any time prior to when a determination needs to be made based on the priorities. Next, the device decides to change the channel in step 306. In accordance with at least one embodiment, the decision to change the channel may be based on a command from the local host, available bandwidth on the current channel, the number of connections on other channels already active, distortions on the current channel or expected distortions due to internal interferences.

[0055] In a step 308, the device shares information with other devices in its network

(e.g., beacon group). This information is related to a contemplated or planned channel change. Step 308 may comprise exchanging information through various information elements (IEs) in beacon transmissions. Alternatively, step 308 may include the exchange of control/command frames (which are non-beacon, payload transmissions containing control/command information).

[0056] After this exchange of information, the device may in step 310, execute the channel change if it is determined, based on the priorities of the existing connections, whether the channel change is prioritized without involving the host in the determination. This channel change may employ different techniques based on various factors. For instance, certain techniques maybe employed when the device has no active connections (e.g., DRP reservations), but may have active PCA data transmissions in the current channel, while other techniques may be employed when the device has one or more active connections (e.g. DRP reservations) in the current channel. In accordance with at least one embodiment, the other device(s) having connections with the device may follow the channel change. Once the channel change is complete, the device may, according to at least one embodiment, continue to search for channel candidates as described in step 302.

[0057] FIG. 3B is a more detailed flowchart of an exemplary channel changing process, according to at least one embodiment. The flow diagram of Fig. 3B represents a computer program and the steps of the flow diagram represent programmed instructions of the computer program that, when executed by a computer program processor, carry out the functions of the at least one embodiment.

Step 320: Initially, a wireless communications device selects a channel finding technique in a first stage, based on whether the device has any active connections in a current channel.

Step 325: The initiating device receives channel change priorities from its host, assigning priorities for various existing connections. In accordance with at least one embodiment, the device may receive the channel change priorities at any time prior to when a determination needs to be made based on the priorities.

Step 330: The initiating device then performs the selected channel finding technique with a plurality of channels to find a candidate channel.

Step 335: The initiating device determines, based on the priorities of the existing connections, whether a channel change is prioritized without involving the host in the determination.

Step 340: If it is determined that the channel change is prioritized, then the initiating device sends a request to at least one remote device to change its channel from the current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval.

Step 350: If the request is successful, the initiating device receives an acceptance of the request from the remote device.

Step 360: Then in a second stage, the initiating device selects a channel changing technique based on whether the device has any active connections in the current channel. Step 370: If it is determined that the channel change is prioritized, the initiating device then executes the selected channel changing technique to change a channel from the current channel to the candidate channel.

Step 380: The initiating device then establishes the desired new connection across the candidate channel with the remote device.

[0058] FIG. 3 C is a flowchart of an exemplary channel changing process according to at least one embodiment executed by a remote device in response of receiving a channel change request from an initiating device. The process of FIG. 3 C includes a step 312 in which a device establishes a connection to a beacon group.

[0059] In step 314, the device receives channel change priorities from its host, assigning priorities for various existing connections. In accordance with at least one embodiment, the device may receive the channel change priorities at any time prior to when a determination needs to be made based on the priorities. Next, in step 316, the device receives, from an initiating device, a request to change its channel from the current channel to a specified channel during an allocated time slot of a beacon period within a repeating time interval.

[0060] In step 318, the device, based on the channel change priorities received in step

314, will either execute the channel change, ask the host what to do or will not follow the channel change. If the device decides to execute the channel change, then in step 322, the device will transmit an acceptance of the request to the initiating device and share the channel change information with the other devices in its network (e.g., beacon group). In accordance with at least one embodiment, the device may transmit the channel change information through various information elements (IEs) in beacon transmissions or alternatively, may transmit control/command frames (which are non-beacon, payload transmissions containing control/command information). Next, in step 324, the device executes the channel change. The channel change may employ different techniques based on various factors. For instance, certain techniques maybe employed when the device has no active connections (e.g., DRP reservations), but may have active PCA data transmissions in the current channel, while other techniques may be employed when the device has one or more active connections (e.g. DRP reservations) in the current channel. In accordance with at least one embodiment, the other device(s) having connections with the device follow the channel change. Commands, Responses and Notifications

1. Channel Change: Description: Tell the UWB radio modem chip to change the connection defined by handle to new channel.

2. Channel Change Allow: Description: Tell the UWB radio modem chip if a remote channel change for handle is allowed and with what priority. priorityThe priority of the connection.

Priority=CCA_NOT_ALLO WED=O means channel change not allowed.

Priority= CCA-QUERY=I means ask for channel change with Channel Change Request Notification.

• Priority>l : If any other connection exists with a higher priority (that has been set using ChannelChangeAllow) then a channel change will not be done. The default value for a new created connection is 1. Thus the Channel Change Request Notification is created for a connection per default when the notification is not masked.

3. Channel Change Request Notification: Description: Asks whether it is allowed to change all existing connections to the specified channel.

The chip will not perform the proposed channel change unless it has been accepted by the UWB radio modem chip host using Channel Change Confirm.

4. Channel Change Confirm: Description: Accepts or rejects a channel change that has been requested by the UWB radio modem chip using Channel Change Request Notification. Certified Wireless USB (CWUSB): Before accepting or rejecting the channel change, the chip host should ask the actual supported channel map from all connected CWUSB devices (using DE VICE_CAP AB ILITIY descriptor). In case a remote device does not support the channel proposed by the UWB radio modem chip, chip host should reject the channel change. If it decides to accepts, it should explicitly disconnect from the respective CWUSB device prior to issuing the ChannelChannelConfirm command.

5. Channel Map Set: Description: This command sets the allowed channels. For WLP and for a CWUSB Host this means: If a connection exists using a channel that is not marked as allowed, the UWB radio modem chip shall move the connection to another

(allowed) channel.

For a CWUSB Device this just means that it updates its databases about the preferred channels (that is used e.g. when returning the DEVICE_CAP ABILITY descriptor in a response to a CWUSB DescriptorGet command).

This commands is affecting the channel map settings for the whole UWB MAC, so for all

PALs using UWB.

Note: It may happen that the UWB radio modem chip is CWUSB Device to A and then a remote CWUSB Device B connects. If the channel map required by B does not match the one sent to A (via DEVICE CAP ABILITY descriptor), then the chip host needs to initiate disconnection from B.

IV. Finding New Channel Candidates

[0061] A device may employ various techniques to find a channel candidate.

Selection of these techniques is based on whether the device has any connections or active data transmissions. More particularly, certain techniques may be selected when a device has joined a beacon group, but has no active connections (e.g., DRP reservations), but may have active PCA data transmissions. Similarly, certain techniques may be employed when a device has an active connection (e.g., a DRP reservation).

A. No Active DRP reservations

[0062] When a device has no active connections, but may have active PCA data transmissions, the embodiments provide two alternative techniques. The first alternative technique involves hibernation. In particular, the device announces (e.g., in a beacon transmission) that it will hibernate. During the device's hibernation period, the device scans the available channels. This scanning is directed at finding either the best available radio channels or at finding a specific target device.

[0063] After finding a new candidate channel, the device returns to original channel and wakes up from the hibernation. Thus, this technique does not require any changes to the WiMedia MAC. [0064] A second alternative shown in Fig. 9 A describing at least one embodiment involves the addition of a new information element (IE) 900 to the current WiMedia MAC. This new Unavailability IE 900 includes three fields. A first field 902 is the element's ID, for example the value 23. A second field 904 gives the length of the following fields, in this case a length of one octet. The third field 906 gives the unavailability duration in units of superframes. In one embodiment, the number of superframes of unavailability is predetermined. In another embodiment, the number of superframes of unavailability is expressly stated in the field 906. Thus, the Unavailability IE 900 contains information, which indicates that the device will be unavailable for a predetermined number of superframes (N superframes). During the device's absence, the other devices in the beacon group still update the device's status in their own beacons. Also during the device's absence, the device scans the available channels for either the best available radio channels or a specific target device.

[0065] Fig. 9B is a flow diagram of the channel finding technique using the

Unavailability information element (IE) 900 according to at least one embodiment. The initial channel finding Steps 320, 325, and 330 of Fig. 9B are the same as those same numbered steps described for Fig. 3B. In Step 320: Initially, a wireless communications device selects a channel finding technique in a first stage, based on whether the device has any active connections in a current channel. In Step 325: The device receives channel change priorities from its host, assigning priorities for various existing connections. In accordance with at least one embodiment, the device may receive the channel change priorities at any time prior to when a determination needs to be made based on the priorities. In Step 330: The device then performs the selected channel finding technique with a plurality of channels to find a candidate channel. In Step 331, the initiating device, based on the selected channel finding technique, broadcasts a beacon with the Unavailability information element (IE) 900 indicating that the initiating device will be unavailable (or that the initiating device will hibernate) for a predetermined number of superframes. Then in Step 332, the initiating device scans for available channels during the predetermined number of superframes, either to find a best available radio channel or to find a specific target device. The following Steps 340 and 350 of Fig. 9B are the same as those same numbered steps described for Fig. 3B. In Step 340: If a suitable channel is found, then the initiating device sends a request to at least one remote device to change its channel from the current channel to the candidate channel during a time slot within a repeating time interval. In Step 350: If the request is successful, the initiating device receives an acceptance of the request from the remote device.

B. Active DRP reservations

[0066] When a device has joined a beacon group and has an active DRP reservation, certain timing delays occur in finding a new channel candidate. For instance, in the context of the current WiMedia MAC, such delays are at least two superframes in duration. More particularly, it may require at least one superframe for the device to synchronize to the new channel and receive needed information from the new channel. In addition, one superframe may be required for the device to synchronize to the old channel again.

[0067] However, it is undesirable for such delays to extend beyond two superframes.

This is because (in the current WiMedia MAC specification) after mMaxLostBeacons, which is currently identified as three superframes in the WiMedia MAC specification, if no beacon is received from a device, all active DRPs are released and device itself is assumed to be lost. To accommodate such constraints, the present embodiment provides various alternative techniques.

[0068] In a first technique, the device sends a beacon in its old channel and changes to new channel. Then the device scans the new channel and returns to the original (old) channel for one or two superframes in order to continue its DRP reservations (as well as to send or receive possible data). Thus, the device scans one channel at a time. This technique does not require changes to the current WiMedia MAC Specification.

[0069] A second technique requires changes to the current WiMedia MAC specification. This technique adds a new field (e.g., a 1-bit field) to the DRP IE. This new field informs peer devices (devices in the beacon group) of the original channel that the device is performing ongoing channel selection operations by including the corresponding field in the DRP IE in its beacon. Upon receiving a DRP IE having this field, the peer device(s) maintain the device's reservation and status in the original channel for a predetermined number (N) superframes (e.g., N = [2, 2 * (# of channels - I)], in the current WiMedia PHY specification 30 channels are defined. Thus, N = [2, 58]). Although this technique requires changes to the WiMedia MAC specification, the current DRP IE has room to accommodate this new field (e.g. in 3-bit Reserved field in DRP Control Field). [0070] A third technique also requires changes to the current WiMedia MAC specification. In this technique, a new field (e.g., a 3-bit field) is added to the DRP IE. This new field informs peer devices (devices in the beacon group) of the original channel that the device is performing ongoing channel selection operations for a certain number of superframes indicated by this new field. For example, when a three bit field is employed such channel selection operations may occur for 1 to 7 superframes. In embodiments, a zero value indicates no ongoing channel selection operations.

[0071] During this indicated number of superframes, the peer device(s) keeps up the device's reservation and status in the original channel by including the corresponding DRP IE in its beacon. As with the second technique, this technique requires changes to the current WiMedia MAC specification. However, the current DRP IE has room to accommodate this new field (e.g. the 3 -bit Reserved field in DRP Control Field).

[0072] According to a fourth technique, the Reservation Status bit of the DRP IE is changed to zero with a new Reason Code called "Channel Selection Ongoing". Upon receiving such a DRP IE, the peer device(s) maintain by including the corresponding DRP IE in its beacon the device's reservation and status in the original channel for a predetermined number (N) superframes (e.g. N = [2, 2 * (# of channels - I)], in the current WiMedia PHY specification 30 channels are defined. Thus, N = [2, 58]). This technique requires changes to the WiMedia MAC specification.

[0073] A fifth technique modifies the current WiMedia MAC specification by adding a new IE for beacon transmissions shown in Fig. 9A. This new IE contains information that the device will be unavailable for a certain number (N) of superframes. Upon receipt of this IE, the peer devices for the DRP reservations maintain (keep up) the device's reservation and the peer devices still update the device status in their own beacons during this period of unavailability.

V. Information Sharing

[0074] Unlike the aforementioned techniques for finding candidate channels, information sharing is independent of any active data transmission. The current WiMedia MAC specification allows a device to inform other devices that it is changing its channel by using the Channel Change IE. However, other devices are not required to follow the device to the new channel.

[0075] To overcome this shortcoming, the present embodiment provides various techniques. For example, a first technique expands the existing Channel Change IE by adding a new list element. The modified Channel Change Information Element 1000 of Fig. 1 OA according at least one embodiment includes the following fields. A first field 1002 is the element ID, for example "18". The second field 1004 is the length of the remaining fields, in this case it is two octets for fields 1006 and 1008 plus two additional octets for each of N device addresses listed in fields 1012 through 1014 to 1016 of the list element 1010. Field 1006 is the channel change countdown and field 1008 is the new channel number being requested by the IE 1000. This new list element 1010 contains device identifiers (DEV IDs) of the peer devices that are requested to change channel with the device originating the modified Channel Change IE 1000. This list 1010 may specify a group of devices that, for example, belong to the same context (e.g. a person's data storage and data display). The Channel Change information element (IE) 1000 shown in Fig. 1OA may include a new channel indicator and a countdown timer.

[0076] Fig. 1 OB is a flow diagram of the channel changing technique using the

Modified Channel Change IE 1000 according to at least one embodiment. The channel finding Steps 320-350 and the initial channel changing Step 360 of Fig. 1OB are the same as those same numbered steps described for Fig. 3B. In Step 361, the initiating device, based on the selected channel changing technique, transmits a beacon including the Modified Channel Change IE 1000 that includes the list 1010 of identifiers of peer devices in the initiating device's beacon group, the information element 1000 including a request to change channel with the initiating device to a new channel number in field 1008.

[0077] Upon receiving such an IE, each device in the list responds with its own

Channel Change IE to accept the request. This IE contains the initiator's DEV ID as well as the same channel and countdown time as in the initiator's message. In Step 362 of Fig. 1OB, the peer devices are shown responding whether they accept the request. Then in Step 370, the initiating device executes the selected channel changing technique to change a channel from the current channel to the candidate channel. [0078] A second technique for sharing channel change information according to at least one embodiment involves modifying the current WiMedia MAC to include a new Channel Change Request IE 1100 as shown in Fig. 11 and a Channel Change Response IE 1200 as shown in Fig. 12. The Channel Change Request Information Element 1100 of Fig. 11 includes the following fields. A first field 1102 is the element ID, for example "24". The second field 1104 is the length of the remaining fields, in this case it is two octets for fields 1106 and 1108 plus two additional octets for each of N device addresses listed in fields 1112 through 1114 to 1116 of the list element 1110. Field 1106 is the channel change countdown and field 1108 is the new channel number being requested by the IE 1100. In the embodiments, the Channel Change Request IE 1100 contains a list 1110 of DEV IDs of peer devices that are requested to change channel with the device transmitting this IE 1100. In addition, the Channel Change Request IE 1100 includes a new channel identifier in field 1108 and a countdown timer in field 1106.

[0079] Upon receiving a Channel Change Request IE 1100, each device in the list responds with its own Channel Change Response IE 1200 shown in Fig. 12 according to at least one embodiment. The Channel Change Response Information Element 1200 of Fig. 12 includes the following fields. A first field 1202 is the element ID, for example "25". The second field 1204 is the length of the remaining fields, in this case it is five octets for fields 1206, 1208, 1210, and 1212. In embodiments, this IE 1200 contains either a positive confirmation or a rejection in field 1206 of the channel change requested in the Channel Change Request IE 1100. Field 1208 is the channel change countdown and field 1210 is the new channel number that the responding device is agreeing to change to, as was requested in the IE 1100. The flow diagram of Fig. 1OB also applies to the channel changing technique using the Channel Change Request IE 1100 of Fig. 11 and the Channel Change Response IE 1200 of Fig. 12.

[0080] A third technique for sharing channel change information involves providing new control/command frames. Thus, this technique requires changes to the current WiMedia MAC specification. For instance, the embodiments add a new command/control frame, Channel Change Request and Response command frame 1300 shown in Fig. 13, which is identified by a Frame Type value in field 1302. An example of Channel Change Command Frame Type Encoding 1400 shown in Fig. 14, with the Frame Type value 1402 indicating the type of Channel Change Command Frame Payload 1404. Command Frames are sent as MAC payload, with the payload occupying N octets in field 1308. A Frame Type 1402 with a first value of "zero" can identify that a Channel Change Request (with information similar to the Channel Change Request Information Element 1100 of Figure 11) is in the payload in field 1308. A Frame Type 1402 with a second value of "one" can identify that a Channel Change Response (with information similar to the information in the Channel Change Response Information Element 1200 of Fig. 12) is in the payload in field 1308. The frame 1300 contains a list of DEV IDs in payload field 1308 for a Channel Change Request, which identifies devices that are requested to change their channel along with the device transmitting this control frame. In addition, this control frame 1300 for a Channel Change Request provides a new channel identifier and a countdown timer in payload field 1308, similar to the information in the Channel Change Request Information Element 1100 of Figure 11.

[0081] Devices included in the device list of the Channel Change Request frame respond with a Channel Change Response frame having information in payload field 1308 similar to the information in the Channel Change Response Information Element 1200 of Fig. 12. This Channel Change Response frame contains either a positive confirmation or a rejection of the requested channel change in payload field 1308, similar to the Channel Change Response Information Element 1200. However, in alternate embodiments, a rejection may instead be made with an additional Channel Change Reject message. For high security devices, command/control frames can be sent in a secure manner.

VI. Channel Change Execution

[0082] In the embodiments, channel change execution is based on whether the changing device has active DRP reservations. If the device has no active DRP reservations, the changing device changes to the new channel' according to channel change information using MAC procedures. Once the channel change has occurred, the device selects a new beacon slot in the new channel and resumes normal mode of operation.

[0083] In the embodiments, when a device changes its channel, other device(s) having DRP reservations with the device follow the channel change as agreed on information sharing phase. Accordingly, if the device has active DRP reservations, the device (and its associated channel changing devices) changes to the new channel according to channel change information using MAC procedures. Once the channel change has occurred, each device selects a new beacon slot in the new channel, hi embodiments, all existing DRPs from the old channel are renegotiated in the new channel.

[0084] Moreover, in the embodiments, after changing channels, a device may be precluded from changing its channel again within a certain time (e.g., 50 superframes). This feature advantageously prevents continuous channel changes (so called "ping-pong" effect)

VII. Information Elements

[0085] In the embodiments, various information elements (IEs) are transmitted to carry out the aforementioned techniques. Such IEs include for example DRP IEs and Channel Change IEs. These IEs are described below with reference to FIGs. 4-12.

[0086] DRP IEs are described with reference to FIGs. 4-6. These IEs are used to negotiate a reservation for certain MASs. In addition, DRP IEs are used to announce the reserved MASs. FIG. 4 is a diagram of a DRP IE format according to the current WiMedia MAC standard. The DRP IE shown in FIG. 4 includes an Element ID field 402, a Length field 404, a DRP Control field 406, a Target/Owner DevAddr field 408, and one or more DRP Allocation fields 410.

[0087] Fields 402 and 404 identify the IE as a DRP IE and indicate its length. FIG. 5 is a diagram showing the format of DRP Control Field 406 according to at least one embodiment. As shown in FIG. 5, this field includes a reserved field 502, an unsafe field 504, a conflict tie-breaker field 506, an owner field 508, a reservation status field 510, a reason code field 512, a stream index field 514, and a reservation type field 516

[0088] Unsafe field 504 indicates whether any of the MASs identified in DRP

Allocation Fields 410 are considered unsafe because they exceed one or more specified reservation limit(s). Such an indication exists when unsafe field 504 is set to "1".

[0089] Owner field 508 is set to "1 " if the transmitting device is the owner of the reservation. Otherwise this field is set to "0" when the transmitting device is the target.

[0090] Reservation status field 510 indicates the status of the DRP negotiation process. For instance, this field is set to "0" when the corresponding reservation is under negotiation or in conflict. In contrast, this field is set to "1" when the transmitting device is confirming a reservation or maintaining an established reservation.

[0091] Reason code field 512 is used by a reservation target. This field indicates whether a DRP reservation request was successful and whether a reservation has been modified. The encoding scheme of this field is provided below in Table 1.

Table 1: Reason Code Field Encoding

[0092] Stream index field 514 identifies the stream of data to be sent in the reservation. Conflict tie breaker field 506 contains a randomly generated bit value.

[0093] Reservation type field 516 indicates the type of reservation. The encoding scheme for this field is provided below in Table 2.

Table 2: Reservation Type Field Encoding

[0094] FIG. 6 provides the format of a DRP Allocation field 410 according to at least one embodiment. As shown in FIG. 6, a DRP Allocation field 410 includes a Zone Bitmap 602 and a MAS Bitmap 604. Zone Bitmap field 602 identifies particular zones containing reserved MASs. If a bit in the field is set to one, the corresponding zone contains reserved MASs. However, if a bit is set to zero, there are no reserved MASs in the corresponding zone. MAS Bitmap 604 indicates which MASs in the zones identified by Zone Bitmap field 602 are part of the reservation. If a bit in field 604 is set to one, the corresponding MAS within each zone identified by the Zone Bitmap is included.

VIII. Wireless Communications Device

[0095] FIG. 7 is a diagram of an exemplary wireless communications device 700, according to at least one embodiment. This device may operate according to the techniques of the present embodiment. This device may be used in various communications environments, such as the environment of FIG. 1. As shown in FIG. 7, device 700 includes a physical layer (PHY) controller 702, a media access controller (MAC) 703, transceiver 704, upper protocol layer(s) 705, and an antenna 710.

[0096] MAC controller 703 generates frames (data transmissions) and beacons for wireless transmission. In addition, MAC controller 703 receives and processes frames and beacon transmissions that are originated from remote devices. MAC controller 703 exchanges these frames and beacon transmissions with PHY controller 702. Li turn, PHY controller 702 exchanges frames and beacon transmissions with transceiver 704. Moreover, in embodiments employing WiMedia, MAC controller 703 performs operations involving the exchange of IEs. For instance, MAC controller 703 is responsible for the processing and generation of IEs, Control/Command frames, and DRP negotiations.

[0097] FIG. 7 shows that transceiver 704 includes a receiver portion 750 and a transmitter portion 760. In the embodiments, transceiver 704 may transmit and receive OFDM signals. Accordingly, in such embodiments, transmitter portion 760 may include components, such as an inverse fast Fourier transform (IFFT) module, a zero padding module, an upconverter, and a transmit amplifier. To receive OFDM signals, receiver portion 750 may include components, such as a downconverter, a receive amplifier, and a fast Fourier transform (FFT) module.

[0098] As shown in FIG. 7, device 700 further includes one or more upper protocol layers 705. These layers may involve, for example, user applications. Accordingly, upper layers 705 may exchange information with remote devices. This involves layer(s) 705 exchanging protocol data units with MAC controller 703. In turn, MAC controller 703 operates with PHY controller 702 and transceiver 704 to transmit and receive corresponding wireless signals.

[0099] The device of FIG. 7 may be implemented in hardware, software, firmware, or any combination thereof. For instance, the components of portions 750 and 760 may include electronics, such as amplifiers, mixers, and filters. Moreover, implementations of device 700 may include digital signal processor(s) (DSPs) to implement various modules, such as components of receiver portion 750 and transmitter portion 760. Moreover, in the embodiments, processor(s), such as microprocessors, executing instructions (i.e., software) that are stored in memory (not shown) may be used to control the operation of various components in device 700. For instance, components, such as PHY controller 702 and MAC controller 703, may be primarily implemented through software operating on one or more processors.

[0100] One such implementation of the FIG. 7 architecture, according to at least one embodiment, is shown in FIG. 8. This diagram illustrates the terminal device implemented according to one embodiment. As shown in FIG. 8, this implementation includes a processor 810, a memory 812, and a user interface 814. In addition, the implementation of FIG. 8 includes transceiver 704 and antenna 710. These components may be implemented as described above with reference to FIG. 7. However, the implementation of FIG. 8 maybe modified to include different transceivers that support other wireless technologies.

[0101] Processor 810 controls device operation. As shown in FIG. 8, processor 810 is coupled to transceiver 704. Processor 810 may be implemented with one or more microprocessors that are each capable of executing software instructions stored in memory 812, for example, as a computer system. In accordance with at least one embodiment, processor 810 may also be implemented as an application specific integrated circuit (ASIC).

[0102] Memory 812 includes random access memory (RAM), read only memory

(ROM), and/or flash memory, and stores information in the form of data and software components (also referred to herein as modules). These software components include instructions that can be executed by processor 810. Various types of software components may be stored in memory 812. For instance, memory 812 may store software components that control the operation of transceiver 704. Also, memory 812 may store software components that provide for the functionality of PHY controller 702, MAC controller 703, and upper protocol layer(s) 705.

[0103] Moreover, memory 812 may store software components that control the exchange of information through user interface 814. As shown in FIG. 8, user interface 814 is also coupled to processor 810. User interface 814 facilitates the exchange of information with a user. FIG. 8 shows that user interface 814 includes a user input portion 816 and a user output portion 818.

[0104] User input portion 816 may include one or more devices that allow a user to input information. Examples of such devices include keypads, touch screens, and microphones. User output portion 818 allows a user to receive information from the device. Thus, user output portion 818 may include various devices, such as a display, and one or more audio speakers (e.g., stereo speakers) and a audio processor and/or amplifier to drive the speakers. Exemplary displays include color liquid crystal displays (LCDs), and color video displays.

[0105] The elements shown in FIG. 8 may be coupled according to various techniques. One such technique involves coupling transceiver 704, processor 810, memory 812, and user interface 814 through one or more bus interfaces. In addition, each of these components is coupled to a power source, such as a removable and/or rechargeable battery pack (not shown).

[0106] FIG. 19 is a diagram of a transceiver 704 in accordance with at least one embodiment. Transceiver 704 may include a radio front-end 1804, a controller 1802, an interface-to-local-host 1800 and an antenna 710. Radio front-end 1804, which is coupled to the antenna 710, maybe configured to exchange information across a current channel through wireless connections with one or more remote devices using the antenna 710. Radio front- end 1804 and antenna 710 may receive information indicative of a channel change by one or more of the remote devices.

[0107] As shown in FIG. 19, radio front-end 1804 is also coupled to the controller

1802. Controller 1802, which is coupled to the interface-to-local-host 1800, determines based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity (i.e., processor 810) in the determination. Controller 1802 may initiate the execution of the channel change if it determines that the channel change is prioritized. Upon the determination that the channel change is prioritized, radio front-end 1804 and antenna 710 may transmit information indicative of the execution of the channel change. The interface to local host 1800 is also coupled, via one or more data buses (not shown) to the processor 810 (local hosting entity). Interface to local host 1800 facilitates the exchange of information between the processor 810 (local hosting entity) and the controller 1802. Controller 1802 receives, through the interface to local host 1800, channel change priorities assigning priorities for the existing connections from the processor 810.

IX. Application Program Interface (API)

[0108] With evolution of technology it is now possible to have different Protocol

Adaptation Layers (PALs) such as Bluetooth (BT) 3.0, Certified Wireless USB (CWUSB), and Wireless Link Control Protocol (WLP) working with one UWB radio defined in European Computer Manufacturers Association (ECMA)-368 specification.

[0109] There exists no standard software interface to the different UWB chipsets, which means much software adaptation on the chipset's Host side is necessary when the chipset is changed. By defining an API the adaptation effort can be reduced.

[0110] The following embodiment is an example of an API for Certified Wireless

USB (CWUSB) and Wireless Link Control Protocol (WLP). The API may, for example, include functionalities such as hiding MAC/PHY related details from chipset's host for reducing the amount of UWB chipset specific details to be programmed on the host side which leaves the host more generic. [0111] The ultimate goal is to have an API on chipset level. This reduces the SW changes needed on chipset's Host side (when changing chipsets) to a minimum. Nevertheless it is also possible that the API is made available as a library (running on chipset's Host side) in case the API on chipset level is different from the API. In that case the chipset vendor can use the already existing chipsets with their own APIs on chip level.

[0112] The basic SW architecture is shown in Figure 15 which describes the case where the API is provided already on chipset level.

EXAMPLE MESSAGE SEQUENCE DIAGRAMS

Notation

[0113] FIG. 16 is an example message sequence diagram for Channel Change. The sequence diagrams use UML 2.0 notation. The API objects in the diagram may be the library API or the chipset API. The sequence diagrams show the flow of commands, responses, notifications and data above the hardware/driver layer. There are three sequence scenarios in FIG. 16.

[0114] The topmost depicted message sequence 1602 takes place when the remote side has initiated a channel change, but the local side did not follow, and thus the proposed connection defined by handle has been lost. A message ChannelChangeAllow(handle, CCA_NOT_ALLOWED) from the local side adaptation layer to the local side API tells the local side chip that a remote channel change for a handle is not allowed. The local chip thus does not accept the channel change and the proposed connection is considered to be lost. The local side API sends a notification to the local side adaptation layer of disconnection for the proposed connection;

NtfDisconnected(handle, DISC_BY_REMOTE_CHANNEL_CHANGE), notifying that the connection defined by handle has been lost.

[0115] The middle depicted message sequence 1604 takes place when the remote side has initiated a channel change. A message ChannelChangeAllow(handle, CCA_QUERY) from the local side adaptation layer to the local side API indicates that the chip is asking its host whether or not to follow the channel change_^ The local side adaptation layer confirms the channel change to the local side API with the message ChannelChangeConfirm(handle, ETrue). The local side chip transmits channel change notices to other wireless devices it is connected to, that the local device will change channels. If the other connections do not follow the channel change of the local device, they get disconnected and the local side API sends a notification to the local side adaptation layer of the other disconnections. If the alternate channel change was not accepted by the initiating remote device, the proposed alternate connection is considered lost and the local side API sends a notification to the local side adaptation layer.

[0116] The bottommost depicted message sequence 1606 takes place when the remote side has initiated a channel change, and both the local device and the remote device have pre- stored channel change priorities, assigning priorities for various connections. Where the priority of the proposed remote channel change is lower than other active link priorities of the local device, then a message ChannelChangeAllow(handle, priority) from the local side adaptation layer to the local side API tells the local side chip that the remote channel change for the handle is not allowed because of its lower priority. Alternately, where the priority of the proposed remote channel change is higher than other active link priorities of the local device, than a message ChannelChangeAllow(handle, priority) from the local side adaptation layer to the local side API tells the local side chip that the remote channel change for the handle is allowed because of its higher priority. Message sequence 1606 depicts a channel change decision without query from the host according to at least one embodiment.

[0117] FIG. 17 is an example message sequence diagram for getting the remote device to change to the current active channel. The sequence diagram uses UML 2.0 notation. The API objects in the diagram may be the library API or the chipset API. The sequence diagram shows the flow of commands, responses, notifications and data above the hardware/driver layer.

[0118] The message sequence begins at the top of FIG. 17 when there are active conditions at the remote device and it has received a channel change request from the local device. A message

Snooze(B_HANDLE_CWUSB_ALL|B_HANDLE_MEDIA_WLP,0,length) from the remote side adaptation layer to the remote side API sets the remote side chip into snooze mode, i.e. the chip falls asleep for the specified interval, wakes up for checking if there is something to transfer (Rx or Tx) for the length of time specified by "length", then falls asleep again. This supports pausing of the current connections for getting a new WiMedia Logical Link Control Protocol (WLP) connection from a different channel to the currently active channel.

[0119] The message sequence continues in the middle of FIG. 17, for the connection and authentication phase. A message ChannelChange(handle, channel) from the remote side adaptation layer to the remote side API tells the remote chipset to change the connection to a new channel. Then the remote side API sends a notification

NtfSnooze(B_HANDLE_CWUSB_ALL|B_HANDLE_MEDIA_WLP,0,time) to the remote side adaptation layer of continuing in the snooze state, but now when the remote chip awakens, it will be in the new channel and can engage in normal traffic.

[0120] FIG. 18 A-E show exemplary channel change decision scenarios in accordance with at least one embodiment. In FIG. 18 A, if device 1 asks for a channel change, no channel change would be done by the local device because connection priority 2 is lower than any other existing connection priority. Similarly, if device 2 asks for a channel change, the channel change will not be executed by the local device because the priority for device 3 is higher than the priority for device 2. If device 3 asks for a channel change, the channel change will be executed by the local device because the connection to device 3 has the highest priority. However, connections to device 1 and device 2 may be lost after the channel change. If the local device asks for a channel change, the channel change is executed but connections to the devices may be lost. It should be noted, that according to at least one embodiment, a transceiver module (not shown) of the local device can, based on the priorities, perform the channel change determination without involving the local hosting entity (not shown) in the determination. However, the priorities are typically provided to the transceiver module by the local hosting entity and the priority information can be provided by the hosting entity at any time prior to when a determination needs to be made based on the priorities.

[0121] In FIG. 18B, if device 1 asks for a channel change and the local host allows the channel change, the channel change is executed. However, device 2 may or may not follow. If the local host does not allow the channel change, the channel change is not executed. If device 2 asks for a channel change, the channel change may be executed without involving the local hosting entity in the determination because the connection to device 1 has a lower priority. If the local device decides to make a channel change, the channel change is executed but connections to the devices may be lost. [0122] In FIG. 18C, if device 1 asks for a channel change, it will not be executed by the local device because the transceiver module of the local device has received instructions from the local hosting entity to not allow channel changes. Similarly, if device 2 asks for a channel change, the channel change will not be executed . If the local device decides to make a channel change, the channel change is executed but connections to the devices may be lost.

[0123] In FIG. 18D, if device 1 decides to make a channel change, it will not be executed by the local device because the transceiver module of the local device has received instructions from the local hosting entity to not allow channel changes. Similarly, if device 2 asks for a channel change, it will not be executed. If the local device decides to make a channel change, the channel change is executed but connections to the devices may be lost.

[0124] In FIG. 18E, if device 1 or device 2 or the hosting entity asks for a channel change, the channel change will be executed but some devices may not follow.

Conclusion

[0125] While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not in limitation. For instance, the features described herein may be employed in networks other than WiMedia networks.

[0126] Accordingly, it will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the embodiments disclosed. Thus, the breadth and scope of the present embodiments should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A method, comprising: exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices; receiving channel change priorities assigning priorities for the existing wireless connections from a local hosting entity; and determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

2. The method of claim 1 , further comprising: transmitting information indicative of execution of the channel change if the determination indicates that the channel change is prioritized.

3. The method of claim 1, further comprising: executing the channel change if the determination indicates that the channel change is prioritized.

4. An apparatus, comprising: means for exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices; means for receiving channel change priorities assigning priorities for the existing wireless connections from a local hosting entity; and means for determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

5. The apparatus of claim 4, further comprising: means for transmitting information indicative of execution of the channel change if the determination indicates that the channel change is prioritized.

6. The apparatus of claim 4, further comprising: means for executing the channel change if the determination indicates that the channel change is prioritized.

7. An apparatus, comprising a transceiver configured for communicating with devices across a wireless communications network; a memory; a processor configured for executing instructions stored in the memory for: exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices; receiving channel change priorities assigning priorities for the existing wireless connections from a local hosting entity; and determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

8. The apparatus of claim 7, wherein the processor is further configured for transmitting information indicative of execution of the channel change if the determination indicates that the channel change is prioritized.

9. The apparatus of claim 7, wherein the processor is further configured for executing the channel change if the determination indicates that the channel change is prioritized.

10. A computer program product comprising a computer usable medium having computer readable program code embodied in said medium, comprising: a computer readable program code for exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices; a computer readable program code for receiving channel change priorities assigning priorities for the existing wireless connections from a local hosting entity; and a computer readable program code for determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

11. The computer program product of claim 10, further comprising a computer readable program code for transmitting information indicative of execution of the channel change if the determination indicates that the channel change is prioritized.

12. The computer program product of claim 10, further comprising a computer readable program code for executing the channel change if the determination indicates that the channel change is prioritized.

13. A transceiver module, comprising: a wireless interface configured for exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices; an interface configured for coupling the transceiver module with a local hosting entity configured for receiving channel change priorities assigning priorities for the existing wireless connections from the hosting entity; and a controller configured for determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

14. The transceiver module of claim 13 , wherein the wireless interface is further configured for transmitting information indicative of execution of the channel change if the controller indicates that the channel change is prioritized.

15. The transceiver module of claim 13, wherein the controller is further configured for initiating execution of the channel change if the determination indicates that the channel change is prioritized.

16. A method, comprising: selecting in a wireless communications device, a channel finding technique based on whether the wireless communications device has any active connections in a current channel; receiving channel change priorities assigning priorities for various existing connections from a local hosting entity; performing the selected channel finding technique with a plurality of channels to find a candidate channel; determining, based on the priorities of the existing connections whether a channel change is prioritized without involving the hosting entity in the determination; sending, if the determination indicates that the channel change is prioritized, a request that at least one remote device change its channel from said current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval; receiving an acceptance of the request from the at least one remote device; selecting a channel changing technique based on whether the wireless communications device has any active connections in the current channel; executing, if the determination indicates that the channel change is prioritized, the selected channel changing technique to change a channel from the current channel to the candidate channel; and establishing a connection across the candidate channel with the at least one remote device.

17. The method of claim 16, wherein said selected channel finding technique further comprises: broadcasting a beacon transmission that the wireless communications device will hibernate; and scanning for available channels during hibernation, either to find a best available radio channel or to find a specific target device.

18. The method of claim 16, wherein said selected channel finding technique further comprises: broadcasting a beacon transmission that the wireless communications device will be unavailable for a predetermined number of superframes; and scanning for available channels during said predetermined number of superframes, either to find a best available radio channel or to find a specific target device.

19. The method of claim 16, wherein said selected channel finding technique further comprises: broadcasting a beacon transmission in the wireless communications device's old channel; scanning in a first new channel; returning to the wireless communications device's old channel for at least one superframe in order to continue communications therein; scanning in a second new channel; and returning to the wireless communications device's old channel for at least one superframe in order to continue communications therein; whereby the wireless communications device scans one new channel at a time either to find a best available radio channel or to find a specific target device.

20. The method of claim 16, wherein said selected channel finding technique further comprises: broadcasting a beacon transmission to inform peer devices in the wireless communications device's beacon group that the initiating device is performing ongoing channel selection operations; said peer devices maintaining the initiating device's reservation and status in the wireless communications device's original channel for a predetermined number of superframes, in response to said broadcasting.

21. The method of claim 16, wherein said selected channel finding technique further comprises: broadcasting a beacon transmission to inform peer devices in the wireless communications device's beacon group that the wireless communications device is performing ongoing channel selection operations for a stated number of superframes; said peer devices maintaining the wireless communications device's reservation and status in the wireless communications device's original channel for said stated number of superframes, in response to said broadcasting.

22. The method of claim 16, wherein said selected channel finding technique further comprises: broadcasting a beacon transmission to inform peer devices in the wireless communications device's beacon group that the wireless communications device will be unavailable for a stated number of superframes; said peer devices maintaining the wireless communications device's reservation and status in the wireless communications device's original channel for said stated number of superframes, in response to said broadcasting.

23. The method of claim 16, wherein said selected channel changing technique further comprises: transmitting an information element including a list of identifiers of peer devices in the initiating device's beacon group, the information element including a request to change channel with the initiating device; and said peer devices responding whether they accept the request.

24. An apparatus, comprising a transceiver configured for communicating with remote wireless communications devices across a wireless communications network; a memory; a processor that is configured for executing instructions stored in the memory for: selecting a channel finding technique based on whether the apparatus has any active connections in a current channel; receiving channel change priorities assigning priorities for various existing connections from a local hosting entity; performing the selected channel finding technique with a plurality of channels to find a candidate channel; determining, based on the priorities of the existing connections, whether a channel change is prioritized without involving the hosting entity in the determination; sending, if the determination indicates that the channel change is prioritized, a request that at least one remote device change its channel from said current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval; receiving an acceptance of the request from the at least one remote device; selecting a channel changing technique based on whether the apparatus has any active connections in the current channel; executing, if the determination indicates that the channel change is prioritized, the selected channel changing technique to change a channel from the current channel to the candidate channel; and establishing a connection across the candidate channel with the at least one remote device.

25. The apparatus of claim 24, wherein the network is a peer-to-peer network.

26. The apparatus of claim 24, wherein the candidate channel and the current channel each employ a corresponding time frequency code (TFC).

27. The apparatus of claim 24, wherein the repeating time interval is a WiMedia superframe.

28. The apparatus of claim 24, wherein the request includes an indicator of the candidate channel and a countdown timer.

29. A computer program product, comprising: a computer readable medium having computer program code therein for enabling a wireless communications device to communicate with remote wireless communications devices across a wireless communications network: program code in the computer readable medium for selecting a channel finding technique based on whether a wireless communications device has any active connections in a current channel; program code in the computer readable medium for enabling the wireless communications device to receive, channel change priorities assigning priorities for various existing connections from a local hosting entity; program code in the computer readable medium for performing the selected channel finding technique with a plurality of channels to find a candidate channel; program code in the computer readable medium for determining, based on the priorities of the existing connections, whether a channel change is prioritized without involving the hosting entity in the determination; program code in the computer readable medium for sending, if the determination indicates that the channel change is prioritized, a request that at least one remote device change its channel from said current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval; program code in the computer readable medium for receiving an acceptance of the request from the at least one remote device; program code in the computer readable medium for selecting a channel changing technique based on whether the wireless communications device has any active connections in the current channel; program code in the computer readable medium for executing, if the determination indicates that the channel change is prioritized, the selected channel changing technique to change a channel from the current channel to the candidate channel; and program code in the computer readable medium for establishing a connection across the candidate channel with the at least one remote device.

30. An apparatus, comprising: means for selecting a channel finding technique based on whether the apparatus has any active connections in a current channel; means for receiving channel change priorities assigning priorities for various existing connections from a local hosting entity; means for performing the selected channel finding technique with a plurality of channels to find a candidate channel; means for determining, based on the priorities of the existing connections whether a channel change is prioritized without involving the hosting entity in the determination; means for sending, if the determination indicates that the channel change is prioritized, a request that at least one remote device change its channel from said current channel to the candidate channel during an allocated time slot of a beacon period within a repeating time interval; means for receiving an acceptance of the request from the at least one remote device; means for selecting a channel changing technique based on whether the apparatus has any active connections in the current channel; means for executing, if the determination indicates that the channel change is prioritized, the selected channel changing technique to change a channel from the current channel to the candidate channel; and means for establishing a connection across the candidate channel with the at least one remote device.

31 A chipset, comprising: at least one radio part and an antenna configured for exchanging information across a current channel through wireless connections with one or more remote devices, wherein the information includes receiving information indicative of a channel change by at least one of the one or more remote devices; one or more data buses coupling the chipset with a local hosting entity configured for receiving channel change priorities assigning priorities for the existing wireless connections from the hosting entity; and a controller configured for determining, based on the priorities of the existing wireless connections, whether a channel change is prioritized without involving the hosting entity in the determination.

32. The chipset of claim 31, wherein the at least one radio part and the antenna are further configured for transmitting information indicative of execution of the channel change if the controller indicates that the channel change is prioritized.

33. The chipset of claim 31 , wherein the controller is further configured for initiating execution of the channel change if the determination indicates that the channel change is prioritized.