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System Simulator >
System Component Models >
IEEE802dot11a >
Scrambler, 802.11a (SCRM11A)

Scrambler, 802.11a (SCRM11A)

Property	Description	Units	Default	Range/Type
MODULATION	Modulation Type	None	0	[0,3]/Integer
CODING	Coding Rate Type	None	0	[0,2]/Integer
LENGTH	Length of PSDU (number of octets)	None	100	[1, 4095]/Integer
S0	Initial state of the scrambler in decimal	None	93	[0, 12]/Integer
RIN	Input impedance	Ohm	Inf	(0, Inf]/Real
ROUT	Output impedance	Ohm	0	[0, Inf)/Real
Ports
Input	Bits before scrambling (integer)
Output	Bits after scrambling (integer)

Limits

Notes

1. This model can be used to scramble the DATA field and then let the tail bits be zero, according to IEEE 802.11a standard.

2. The DATA field, composed of SERVICE, PSDU, tail, and pad parts, shall be scrambled with a length-127 frame-synchronous scrambler. The frame synchronous scrambler uses the generator polynomia S(x)l as follows, and is illustrated in Fig.1.

(1)
The 127-bit sequence generated repeatedly by the scrambler shall be (leftmost used first), 00001110 11110010 11001001 00000010 00100110 00101110 10110110 00001100 11010100 11100111 10110100 00101010 11111010 01010001 10111000 1111111, when the “all ones” initial state is used. The same scrambler is used to scramble transmit data and to descramble receive data. When transmitting, the initial state of the scrambler will be set to a pseudo random non-zero state S_d. The seven LSBs of the SERVICE field will be set to all zeros prior to scrambling to enable estimation of the initial state of the scrambler in the receiver.

3. The 6 tail bits should be reset to “zero”. The position of the tail bits can be determined by the three parameters, Modulation, Coding, and Length. The position of the first tail bit is determined by:

(2)
For the calculation of N_Data, please refer to the pad11a model.

Fig.1 Data scrambler

Netlist Form

SCRM11A:NAME n1 n2 [MODULATION =val] [CODING =val]
+ [LENGTH =val] [S0=val] [RIN=val] [ROUT=val]

Netlist Example

SCRM11A:1 1 2 MODULATION = 2 CODING= 2 LENGTH = 100 S0 = 93

References

1. IEEE Std 802.11a, Part 11: “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5 GHz Band,” ISO/IEC 8802-11:1999/Amd 1:2000(E).

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