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Differences Between Link Manager (LM) & Link Controller (LC)
Original Post: Link Manager and Link Controller (SIG Forum)
Date: 2000-04-13
The Link Controller (LC) performs the baseband processing, i.e.
- packet handling composing and decomposing,
- frequency hopping,
- ARQ,
- FEC coding,
- Audio Coding,
- Encryption,
The LC also controls the low-level link routines for connection
establishmentss i.e..
- inquiring,
- inquiry scanning and responsing,
- paging,
- page scanning and responsing.
In essence, the LC is the DSP part of BT-hardware.
The Link Manager (LM) is the software running on a CPU core (e.g. a
RISC Processsor) or the CPU core with it software (firmware). It is used
for link setup and link control.
The 2 different parts work together. For examples, with connnection
establishments with page scanning, the LC scanns for page messages,
receives and decodes page messages, gives them to the LM. The LM handles
and filters these messages, makes decisions, and gives its instructions to
the LC. Furthermore, the LM is responsible for controlling the links.
However even though the LM controls the connection. The state diagram
of the LC (Baseband Specs, p98) is a description of the 'connections'.
This is due to the fact that these all are the states of the LC. The LC
can change its state via an instruction from the LM (or via internal
signals).
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