Introduction

General Overview

The Connection Layer controls the state of the air-link, and it
prioritizes the traffic that is sent over it.

This section presents the default protocols for the Connection
Layer. With the exception of the Overhead Messages Protocol, each
of these protocols can be independently negotiated at the beginning
of the session.

The access terminal and the access network maintain a connection
whose state dictates the form in which communications between these
entities can take place. The connection can be either closed or
open:

• Closed Connection: When a connection is closed, the access
terminal is not assigned any dedicated air-link resources.
Communications between the access terminal and the access network
are conducted over the Access Channel and the Control Channel.

• Open Connection: When a connection is open, the access
terminal can be assigned the Forward Traffic Channel, and is
assigned a Reverse Power Control Channel and a Reverse Traffic
Channel. Communications between the access terminal and the access
network are conducted over these assigned channels, as well as over
the Control Channel.

The Connection Layer provides the following connection-related
functions:

• Manages initial acquisition of the network.

• Manages opening and closing of connections.

• Manages communications when connection is closed and when a
connection is open.

• Maintains approximate access terminal's location in either
connection states.

• Manages radio link between the access terminal and the access
network when connection is open.

• Performs supervision both when the connection is open and when
it is closed.

• Prioritizes and encapsulates transmitted data received from
the Session Layer and forwards it to the Security Layer.

• De-capsulates data received from the Security Layer and
forwards it to the Session Layer.

The Connection Layer performs these functions through the
following protocols:

• Air Link Management Protocol: This protocol maintains the
overall connection state in the access terminal and the access
network. The protocol can be in one of three states, corresponding
to whether the access terminal has yet to acquire the network
(Initialization State), has acquired the network but the connection
is closed (Idle State), or has an open connection with the access
network (Connected State). This protocol activates one of the
following three protocols as a function of its current state.

• Initialization State Protocol: This protocol performs the
actions associated with acquiring an access network.

• Idle State Protocol: This protocol performs the actions
associated with an access terminal that has acquired the network,
but does not have an open connection. Mainly, these are keeping
track of the access terminal's approximate location in support of
efficient Paging (using the Route Update Protocol), the procedures
leading to the opening of a connection, and support of access
terminal power conservation.

• Connected State Protocol: This protocol performs the actions
associated with an access terminal that has an open connection.
Mainly, these are managing the radio link between the access
terminal and the access network (handoffs, handled via the Route
Update Protocol), and the procedures leading to the close of the
connection.

In addition to the above protocols, which deal with the state of
the connection, the Connection Layer also contains the following
protocols:

• Route Update Protocol:This protocol performs the actions
associated with keeping track of an access terminal's location and
maintaining the radio link between the access terminal and the
access network. This protocol performs supervision on the
pilots.

• Overhead Messages Protocol: This protocol broadcasts essential
parameters over the Control Channel. These parameters are shared by
protocols in the Connection Layer as well as protocols in other
layers. This protocol also performs supervision on the messages
necessary to keep the Connection Layer functioning.

• Packet Consolidation Protocol: This protocol consolidates and
prioritizes packets for transmission as a function of their
assigned priority and the target transmission channel.

The Air Link Management Protocol, its descendants and the
Overhead Messages Protocol are control protocols. The Packet
Consolidation Protocol operates on transmitted and received
data.