In Phase I the ES nodes act in a distributed manner to determine which ES
will become the master ES. The
master ES collects position information, determines the optimum
ES interconnections, and distributes the results back to the
ES nodes. The ES nodes determine the master ES by broadcasting **MYCALL**
packets and collecting **MYCALL** packets until the
MYCALL Timer expires with a prespecified time, *T*. The **MYCALL**
packets contain the callsign and boot-time
of each ES. The ES with oldest boot-time is designated as the master.
*T* should be chosen as the smallest value
which allows enough time for all **MYCALL** packets to be received.
This would be approximately 0.492 * (*N*-1) seconds, where *N* is the
total number of ES nodes. **NEWSWITCH**
packets take on the order of 0.439 seconds to transfer, and therefore, it
will take 0.439 * (*N*-1)
seconds to send these packets.
The ES nodes will respond with **SWITCHPOS** packets which will take
another 0.679 * (*N*-1) seconds.
These events occur after each **MYCALL** packet has been received,
and can occur before the MYCALL Timer has expired.

The next step in Phase I is to run the topology algorithm which is
based on a consistent labeling algorithm [15]. This algorithm
generates all fully connected topologies given ES node locations and
constraints on the antenna beams such that beams do not interfere with
one another. The information required by the topology module is the
GPS location of all ES nodes, transmit and receive beam widths, transmit
radius, the number of non-interfering frequency pairs, and an interference
multiplier. An interference multiplier of 1.0 assumes adaptive power
control, in which case it is assumed that beam power control will be
adjusted to exactly match the link distance. The interference multiplier
multiplied by a link's actual length will determine the range of
interference created by the link.
This takes on the order of seconds
where *L* is the number of available frequency pair
combinations with the addition of 1 for no link. Assigning distinct
frequencies allows beams to overlap without interference.
*R* is the number
of constrained links and is a constant. The constraints are
based on maximum beam length, beam widths, and number of frequencies
which can be supported.

The final step in Phase I is to distribute the topology information
to all ES nodes in **TOPOLOGY** packets. This takes approximately
0.664 + (0.1 * (*N*-1)) seconds.

The time for Phase I to complete as a function of N is shown in Equation 1.

Tue Nov 12 11:48:31 CST 1996