Specifications

Handover Operation
Handover
D-10 68P81095E55-E August 08, 2000
Handover System
Defaults
Handover is a coordinated effort between the FNE and the mobile. System and
mobile software continuously monitors Cell-information on Broadcast Control
Channel (BCCH). This process is driven by over-the-air (radio link) parameters.
The MS continuously measures parameters during call. The parameters are:
- SQE = C/(I+N)
- RSSI
- Primary host channel (every 90 ms)
- One non-host channel (every 90 ms)
The process samples neighbor list candidates (Ideally, 7 samples on 3 channels).
Less ideal could use 3 samples on 5 channels. When MS detects trouble on the host,
or a better neighbor cell:
- The MS sends signal measurement samples to the FNE
- The FNE evaluates potential servers
- The FNE assigns new host
- The MS switches to new host
Note
Interference in handover activity is not part of normal handover calculations. If
interference affects another mobile after handover, the affected mobile will in
turn, undergo handover. Load Balancing is not part of the handover algorithm.
High Site / Low Site The iDEN system selects hosts according to the type of call being made.
Interconnect calls require more system resources and must maintain a better RF link
(operates better on low sites). Dispatch call do not require as many system resources
and can operate in less restrictive RF environments (operates on high sites).
Each cell broadcasts a neighbor cell list that specifies the host candidates the MS
should measure for cell re-selection, handover and re-connection. Each entry in the
neighbor cell list contains three class values:
• Reselection class
• Handover class
• Reconnection class
Each of these classes has a hierarchy (preference) of each neighbor cell. Each of
these class values is software configurable at the OMC. By properly setting up these
parameters, MS will operate on either a high site or a low site to provide best
performance and optimize system resources (RF channels), for example:
1) The MS tends to stay with (camp-on) and conduct calls with the high site cells
(for more efficient operation of dispatch calls).
2) The MS tends to use the low site cells on interconnect calls (for better utilization
of RF hosts). (The MS will use a high site cell if that was the only way to keep the
call alive.)