must be set to 0B and should be ignored by the Receiver (see Table 5-3). The remainder of the payload portion of a protocol data packet is application-specific data. Protocol data packets can be transmitted at any of the implementation supported bit transfer rates.

•A protocol handshake packet. Protocol handshake packets are encoded as Data Frame in the MAC

Header. Protocol handshake packets can only be transmitted by a device and only during a WDTCTA time slot (see Section 5.2.1). Protocol handshake packets must include the Wireless USB Header with the bmAttributes.PID field set to HNDSHK and the bmAttributes.EndpointDirection field set to the direction of the endpoint generating the handshake packet. In addition they must be transmitted using secure packet encapsulation unless explicitly specified otherwise. When secure packet encapsulation is present, the Encryption Offset field in the Security Header is set to six (6). The entire handshake packet is transmitted in plain text but is still protected by the MIC. Protocol handshake packets are small, however important portion of the protocol, and must be transmitted as reliably as possible, so therefore must transmitted at the most reliable bit transfer rate (i.e. PHY Base signaling rate).

Table 5-4. Handshake Packet Format

•A device notification packet. Device notification packets are encoded as Data Frame in the MAC

Header. Device notification packets can only be transmitted by a device, during a WDNTSCTA time slot (see Sections 5.2.1 and 5.3). Device notification packets are transmitted using secure packet encapsulation unless explicitly specified otherwise. Device notification packets must include the Wireless USB Header with the bmAttributes.PID field set to DN and the bmAttributes.EndpointDirection field must be set to 0B by the device and may be ignored by the host. Note that some device notifications are transmitted without secure packet encapsulation because they are transmitted outside of the secure relationship (i.e. like the Connect notification). Refer to Section 5.3 for details about device notifications. The data payload portion of the packet is used to convey specific notification information from the device to the host. When secure packet encapsulation is present, the Encryption Offset field in the Security Header is set to the length of the Wireless USB header plus the length of the notification payload. In short, the entire packet is transmitted in plain text in form similar to an MMC (see above).

The host may determine that it does not have any pending transactions for a reservation period and can ‘release’ the remainder of the period by directing all devices in the cluster for which the reservation applies to transmit a UDR control packet which allows non-Wireless USB device in range to utilize the remainder of the reservation period.

5.2Wireless USB Transaction Groups

This section provides a general overview of how the USB transactions are accomplished via Micro-scheduling, defines general structure for the MMC (Micro-scheduled Management Command) and also defines the valid information elements for an MMC.

A Wireless USB Micro-scheduled sequence is comprised of an MMC (transmitted by the host) and the subsequent channel time which is described in the MMC. Wireless USB uses the structure of a Micro-scheduled sequence to manage the Wireless USB transaction protocol. In general, a Micro-scheduled sequence may include one or more Wireless USB transactions and is generally referred to in the remainder of this specification as a Transaction Group. Figure 5-2 illustrates the general format of a transaction group. Note that a transaction group is simply a structure for running Wireless USB transactions. The host dynamically manages the contents

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