3 Coding Parameters for EDGE
Data rate per time
Scheme Code rate Modulation slot (kbps)
MCS-9 1 8-PSK 59.2
MCS-8 0.92 8-PSK 54.4
MCS-7 0.76 8-PSK 44.8
MCS-6 0.49 8-PSK 29.6
MCS-5 0.37 8-PSK 22.4
MCS-4 1 GMSK 17.6
MCS-3 0.85 GMSK 14.8
MCS-2 0.66 GMSK 11.2
MCS-1 0.53 GMSK 8.8
I-Axis
Q-Axis
(0, 1, 1)
(0, 1, 0)
(1, 1, 1)
(1, 1, 0)
(1, 0, 0)
(1, 0, 1)
(0, 0, 1)
(0, 0, 0)
FIGURE 1.12 EDGE signal constellation diagram mapping for
8-PSK.
(1.6)
(1.7)
Atechnique used in PS transmissions is called Incremental Redundancy (IR). This technique estimates
the link quality and selects a strategic MCS combination in order to maximize the user bit rate.
With IR, the packet is first sent with little coding overhead in order to produce a high bit rate, if decoding
is successful. If packet decoding fails, additional coding (or redundancy) is sent until the packet
is received successfully or a time-out occurs. Obviously, the more retransmission and coding performed,
the lower is the user bit rate and higher is the overall system delay. Differing code rates are
accomplished by puncturing different bits each time a packet retransmission occurs.
Some of the technical hurdles to overcome with EDGE (and GPRS) deployment are:
1.
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