Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
One of the two possible schemes explained below can be used to send the vendor dependent information within the
maximum capabilities messages (MAX_CAP_MSG(xxx)):
• Indexed scheme: Only the vendor related information shall be sent, and the maximum capabilities shall be
inferred by the receiver. As a result, less data shall be transferred by the Capabilities Exchange protocol,
minimizing the overhead.
• Enumerated scheme: Node vendor and capabilities shall be sent as an enumeration.
In case a node does not understand the indexed scheme, it shall send a NACK to the sender in response. In any case,
the common capabilities section is always sent in the message using an enumerated scheme.
The information within the running capabilities messages (RUN_CAP_MSG) shall be sent in a different way. First,
a field containing the default mode shall be sent. This field shall indicate what shall be the value for a running
capability that is not sent in the message. The possible values can be two:
• Maximum capability.
• Minimum capability.
Once the default field content is clear, the running capabilities that do not match with this default value shall be sent
using a group of two fields. The first one shall indicate the position of the capability in the NCT, and the second
one, its value. In addition to the information itself, a message mode shall be filled, indicating whether the node has
changed its running capabilities, or it is a simply information message to the others nodes.
9.1.4.5.3.1 Capability Element (CapE)
A capability element is a structure composed by several and variable number of fields. All protocol messages are
built using this structure. Four can be the protocol messages to be composed:
• MAX_CAP_MSG(xxx): This message shall contain the maximum capabilities that a node can perform. It
shall be divided into two main sections. The first one is the common capabilities section, which includes all
these capabilities that are vendor independent, and have been previously approved by all vendors as a
standard. The second one is the vendor capabilities section that shall be divided into three subsections.
Either these subsections can be transmitted entirely (enumerated scheme) or sent using only an index
(indexed scheme), enough for the receiver to understand all the capabilities related to each subsection. In
this case, the indication (xxx) shall be substituted by a 1 in the position relative to each of the subsections.
That is, if only the Chip related capabilities are sent using the index, the indication becomes (100). The
subsections are the following:
o Chip related capabilities: All the capabilities that depend directly on the chip. If sent by index, it
shall be indicated with a 1 in the first position of the index indicator. A list of Chip related
capabilities is presented in section 0.
o Firmware related capabilities: All the capabilities that depend on the Firmware version. If sent by
index, it shall be indicated with a 1 in the second position of the index indicator. A list of Firmware
related capabilities is presented in section 0.
o Reference Design related capabilities: All the capabilities that depend on the Reference Design. If
sent by index, it shall be indicated with a 1 in the third position of the index indicator. A list of
Reference Design related capabilities is presented in section 0.
• RUN_CAP_MSG: In this message, the running but not the maximum capabilities of the node shall be sent.
Its objective is to fill the PCT. The first field shall notate the transmission mode, where the nature of the
message, if it is a simply informational message or includes a notification of change in the running
Submission page 220 UPA-OPERA