IS-95A Rev Ch Convolutional Encoder (CDMA Reference Blockset)

Convolutionally encode the input data frame

Library

IS-95A Mobile Station Transmitter

Description

This block convolutionally encodes the input data frame. The data frame is composed of information bits, CRC and tail bits for reverse channels according to the IS-95A specification. Note that as a result, the last 8 bits of each Traffic or Access channel input frame must be 0.

The encoder's constraint length is nine. For the Access channel and Traffic channel Rate Set I, the convolutional encoder implements a rate 1/3 code whose generator functions are 557 (octal), 663 (octal), and 711 (octal). For Traffic channel Rate Set II, the convolutional encoder implements a rate 1/2 code whose generator functions are 753 (octal) and 561 (octal).

The input frame size is equal to the maximum possible size of 288 (Rate Set II, Traffic Full Rate). Similarly, the output size equals the maximum possible size of 576 (Rate Set II, Traffic Full Rate). The relevant number of input and output bits is specified in the table below. The block ignores input bits beyond the relevant bits, and sets output bits beyond the relevant bits to zero.

Channel Type
Number of Relevant Input Bits
Number of Relevant Output Bits

Access
96
288

Traffic, Rate Set I, Full Rate
192
576

Traffic, Rate Set I, Half Rate
96
288

Traffic, Rate Set I, Quarter Rate
48
144

Traffic, Rate Set I, Eighth Rate
24
72

Traffic, Rate Set II, Full Rate
288
576

Traffic, Rate Set II, Half Rate
144
288

Traffic, Rate Set II, Quarter Rate
72
144

Traffic, Rate Set II, Eighth Rate
36
72

Channel Type	Number of Relevant Input Bits	Number of Relevant Output Bits
Access	96	288
Traffic, Rate Set I, Full Rate	192	576
Traffic, Rate Set I, Half Rate	96	288
Traffic, Rate Set I, Quarter Rate	48	144
Traffic, Rate Set I, Eighth Rate	24	72
Traffic, Rate Set II, Full Rate	288	576
Traffic, Rate Set II, Half Rate	144	288
Traffic, Rate Set II, Quarter Rate	72	144
Traffic, Rate Set II, Eighth Rate	36	72

Inputs

Rate

Integer scalar that specifies the data rate for the input signal. To indicate a rate fraction of Full, Half, Quarter, or Eighth, use an input value of 0, 1, 2, or 3, respectively. The table below shows all valid channel types and rate fractions, along with their associated data rates and Rate input values.


Channel Type	Data Rate (bps)	Rate Input Value
Access (always Half rate)	4800	1
Traffic, Rate Set I, Full	9600	0
Traffic, Rate Set I, Half	4800	1
Traffic, Rate Set I, Quarter	2400	2
Traffic, Rate Set I, Eighth	1200	3
Traffic, Rate Set II, Full	14400	0
Traffic, Rate Set II, Half	7200	1
Traffic, Rate Set II, Quarter	3600	2
Traffic, Rate Set II, Eighth	1800	3

Frame In

Binary vector of size 288 representing a frame to be encoded.

Outputs

Binary vector of size 576 representing an encoded frame.

Dialog Box

Parameters

Rate set: The rate set, either Rate Set I or Rate Set II.
Channel type: The channel type, either Access or Traffic.
Initial encoder state: Integer vector of size three that provides the initial state of the convolutional encoder. If this is an empty vector, then the block defaults to zero for all states.

Specification References

IS-95A 7.1.3.1.3
J-STD-008 3.1.3.1.3

IS-95A Rev Ch Burst Randomizer IS-95A Rev Ch Detector