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IEEE802dot11a >
   Preamble Generator, 802.11a (PREAM11A)       

Preamble Generator, 802.11a (PREAM11A)

 

 


Property

Description

Units

Default

Range/Type

RIN

Input impedance

Ohm

Inf

(0, Inf]/Real

ROUT

Output impedance

Ohm

0

[0, Inf)/Real

Ports

Output

Preamble field (integer)

 

Notes

1. This model can be used to generate PLCP Preamble according to IEEE 802.11a standard.

2. The PLCP preamble field is used for synchronization. It consists of 10 short symbols and two long symbols shown in Fig.1.

Fig.1 OFDM training structure

3. Fig.1 shows the OFDM training structure (PLCP preamble), where fl and fID to denote short training symbols and Tl and T1 denote long training symbols. The PLCP preamble is followed by the SIGNAL field and DATA field. The total training length is 16ms. The dashed bound­aries in the figure denote repetitions due to the periodicity of the inverse Fourier transform.

4. A short OFDM training symbol consists of 12 subcarriers, which are modulated by the ele­ments of the sequence S, given by
The multiplication by a factor of (13/6)1/2 is in order to normalize the average power of the resulting OFDM symbol, which utilizes 12 out of 52 subcarriers. To meet 64-point IFFT requirement, 11 “zero” shall be put in subcarriers –32~-27 and 27~31, respectively. These samples are transformed using IFFT, extended periodically for 161 samples (about 8 ms), and then multiplied by the window function:



(2)

5. A long OFDM training symbol consists of 53 subcarriers (including a zero value at dc), which are modulated by the elements of the sequence, L, , given by


(3)
To meet 64-point IFFT requirement, 11 “zero” shall be put in subcarriers –32~-27 and 27~31. The time domain samples are produced by performing IFFT, cyclically extending the results to get cyclic prefix, and then multiplied by the window function:



(4)
The resulting 161 samples are appended with one sample overlap to the SIGNAL field symbol.

Netlist Form

PREAM11A:NAME n1 [RIN=val] [ROUT=val]

Netlist Example

PREAM11A:1 1

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).

2. J. Terry and J. Heiskala, Proakis, OFDM Wireless LANs: A Theoretical and Practical Guide, Sams Publishing, 2002.



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