7.5.3 Wireless USB Channel Change Announcement IE

The Channel Change Announcement IE is used by a host to announce the Wireless USB channel time at which devices must begin listening to a different PHY channel for continuation of the current Wireless USB Channel transmissions. The format of this information element is detailed in Table 7-41.

Table 7-41. Channel Change Announcement Information Element

The allowable values of bNewPHYChannelNumber depend on the PHY channels supported by the host and the members of its Wireless USB Cluster. Refer to Section 4.10.4 for rules for SwitchTime values and other operational requirements for devices. Refer to 5.6 for a summary about valid values for the bNewPHYChannelNumber field.

•Stop Retransmission Condition: the host must cease transmitting this IE after the channel switch has completed.

7.5.4 Wireless USB Device Disconnect IE

The Device Disconnect IE is used to send Disconnect notifications to one or more specific devices. The format of this IE is illustrated in Table 7-42.

Table 7-42. Format of a Wireless USB Device Disconnect IE

The purpose of this information element is to allow the host to notify one or more devices that it is being disconnected.

•Stop Retransmission Condition: the host will cease transmitting this IE after at least 100 ms have elapsed and it has transmitted at least 3 MMCs that include this IE for the device(s).

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7.5.5 Wireless USB Host Disconnect IE

The Host Disconnect IE is used to send Disconnect notifications to all devices in the cluster. The format of this IE is illustrated in Table 7-43.

Table 7-43. Format of a Wireless USB Host Disconnect IE

The purpose of this information element is to allow the host to notify all devices that they are being disconnected.

•Stop Retransmission Condition: the host will cease transmitting this IE after at least 100 ms have elapsed and it has transmitted at least 3 MMCs that include this IE.

7.5.6 Wireless USB Release Channel IE

The Release Channel IE is used to inform non-Wireless USB devices that the host is making the remainder of the current MAC Layer channel reservation block available to them for data communications. This means the host will not be using the channel time for Wireless USB channel data communications. The format of this IE is illustrated in Figure 7-6.

Figure 7-6. Format for Release Channel IE

The bLength field includes the total length of the Release Channel Time information element, including the bLength field. This information element is comprised of one or more Unused DRP Release Blocks (UDRB). Each UDRB allocates Wireless USB channel time for a device to transmit a MAC Layer-defined UDR control packet. Note that a UDR control packet has only a MAC Header and no payload. See reference [3] for details. The format of a UDR Block is illustrated in Table 7-44.

Table 7-44. Unused DRP Release Block for WRELEASE_CHANNEL_IE

The device whose Wireless USB cluster address matches the value of bDeviceAddress must begin transmitting a UDR control frame when its internal clock matches wStart. The interpretation of wStart is the same as that documented in Section 5.3 for WXCTAs. The device must format the UDR as specified in Table 7-45 and it must use the wDurationValue provided in the associated UDRB in the Duration field of the UDR packet.

The host must ensure that the wDurationValue field values are consistent with the requirements of the MAC Layer specification. The host uses the inter-slot times defined in Section 5.3.2 for providing guard times between UDR transmission slots.

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Table 7-45. Field Contents for a UDR Packet (MAC Layer Packet Only)

All device implementations must implement this feature. The UDR packet must be transmitted at maximum available transmit power.

Note, that the host must also transmit a properly annotated UDR packet. The host may transmit it’s UDR either before or after the channel time described and allocated by this IE.

•Stop Retransmission Condition: the host will transmit this IE only once.

7.5.7 Wireless USB Work IE

The host includes a Work IE in MMCs in response to a Sleep notification from one or more devices. Section 4.16 in the Data Flow chapter describes the full operation.

Table 7-46. Format of a Wireless USB Work IE

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Table 7-46. Format of a Wireless USB Work IE (cont.)

•Stop Retransmission Condition: the host will transmit this IE for at least 3 MMCs.

7.5.8 Wireless USB Channel Stop IE

The host includes a Channel Stop IE in MMCs before stopping a USB channel. Section 4.16 in the Data Flow chapter describes the full operation.

Table 7-47. Format of a Wireless USB Channel Stop IE

•Stop Retransmission Condition: the host will remove this IE from the Wireless USB channel when it is no longer in need of polling for remote wake notifications. If the host is not transitioning to a channel stop or is not open for remote wake notifications, then it must not include this IE in the Wireless USB channel.

7.5.9 Wireless USB Device Keepalive IE

The Device Keepalive IE is used to direct one or more Wireless USB cluster members to begin transmitting DN_Alive notifications. The purpose of this IE is described in Section 4.14. The frequency and placement of this IE in MMCs is host-dependent.

Table 7-48. Format of a Wireless USB Keepalive IE

•Stop Retransmission Condition: the host will remove a device address from this IE once it has successfully received a DN_Alive notification from that device.

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