Frequency Hopping - Ericsson CME 20 R6.1 Reference Manual

13

Frequency Hopping

"Frequency hopping" means that the radio frequency channel of a BPC
may change on a per TDMA frame basis. Frequency hopping improves
the quality of the transmission on the air interface.
The Frequency hopping function is used to increase the efficiency of the
channel coding and interleaving in the following situations:
•
•
There are two types of frequency hopping available:
•
•
13.1 References
/GSM 08.58/
/GSM 05.02/
Whenever a reference is made to a function described in another chapter,
please refer to the table of contents to find the appropriate chapter.
13.2 Concepts
Baseband Hopping
Synthesiser Hopping
13.3 Function
Frequency hopping is provided on a slot-by-slot basis according to /
GSM:05.02.6.2/.
Supported channel combinations /GSM:05.02:6.4/:
•
•
•
EN/LZT 123 2697 R5A
1998-08-13
Multipath (or Rayleigh) fading
−
Is often frequency-dependent. In case of a dip, changing
of frequencies reduces this problem.
Interference problems
−
Without frequency hopping, a connection may experience
high interference for a long time. With frequency
hopping this time is shortened. However, frequency
hopping does not reduce the overall system interference
level, but averages it.
Baseband hopping
Synthesiser hopping
(i) TCH/F+FACCH/F+SACCH/TF
(ii) TCH/H(0,1) + FACCH/H(0,1) + SACCH/TH(0,1)
(vii) SDCCH/8 [0..7]+SACCH/C8 [0..7]
© Ericsson Radio Systems AB
— All Rights Reserved —
GSM 08.58 (phase 2) version: 4.2.0
GSM 05.02 (phase 2) version: 4.3.0
Each transmitter will always transmit on
the same frequency. The physical channel
data will be sent from different
transmitters with every burst.
The physical channel data will be sent
from the same transmitter all the time.
But the transmitter will use a new
frequency with every burst.
Frequency Hopping
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