tree bed68b37c8c89545fe41b00b3747d9a58adea428
parent 829db22eeb273fe1fedfcd5e1d5e56c6824d53e9
author Neels Hofmeyr <neels@hofmeyr.de> 1605230077 +0100
committer Neels Hofmeyr <neels@hofmeyr.de> 1605707425 +0100

hodec 2: favor moving dyn TS

When a used timeslot gets moved to another timeslot for load balancing, prefer
moving a dynamic timeslot, as illustrated by handover_test.c test 30.

Rationale: freeing up a dynamic timeslot is better for PDCH availability, as
well as for flexibility in timeslots. Test 30 shows that when freeing a static
TCH/F even though a dynamic one with identical ratings is in use, later
handovers to a TCH/H may become impossible, because no more dynamic timeslots
are available to switch to TCH/H. A freed dynamic timeslot allows congestion
resolution to continue and reduce more TCH/F to TCH/H.

The scope of this preference is per-TRX, where the RXLEV ratings used for
picking a target lchan are the same by definition. In other words, this never
overrules picking another lchan that has better RXLEV.

Among lchans on dynamic timeslots that could be moved, this code favors moving
later lchans; mainly because it makes for a simpler condition in the code.

Change-Id: Ic221b8d2687cdec0bf94410c84a4da43853f0900