msm7730 Oki Semiconductor, msm7730 Datasheet - Page 10

• Manufacturer Part Number: msm7730
• Description: Wireless Lan Baseband Controller
• Manufacturer: Oki Semiconductor

The MSM7730 supports two modes:
The demodulator offers three possible interfaces to a limiter/discriminator radio.
The radio requirements for the demodulator are:
PHY Interface
The PHY section of the MSM7730 allows the MAC layers from two different stations to be interconnected
via a 2.4-GHz radio signal. Figure 6 shows a block diagram of the PHY interface.
The PHY provides a slow Frequency Hopping Spread Spectrum (FHSS) radio link at either 1 or 2 Mbps.
FH is performed over a subset of 1-MHz wide channels with a frequency band of 2.400 to 2.497 GHz. The
MSM7730 is not directly in control of the hopping sequence, but rather provides for reprogramming of
the radio channel so that this function can be managed under software control.
The mapping of data between the MAC and the radio link is called the Physical Layer Convergence Pro-
tocol (PLCP). This mapping involves the addition and removal of preamble and header information, as
well as the whitening and dewhitening of packet data. Figure 7 shows a block diagram of the PLCP.
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• 1-Mbps 2-ary FSK
• 2-Mbps 4-ary FSK
• Analog data slicer (1Mbps only)
• Post discriminator 4-bit ADC (offset binary)
• Post discriminator 1-bit ADC (provisional)
• 1 Mb: 20 dB S/N from discriminator 10
• 2 Mb: 30 dB S/N from discriminator 10
• Discriminator linearity of ±5% required for specified 2-Mbps operation
• 4-bit discriminator-to-ADC ranging, to cover approximately ±360 KHz
• Carrier acquisition for analog slicer option within 4 µs, yielding a duty cycle better than 60:40 for a
• RSSI threshold decision within 4 µs of antenna switching
• 3-state ADC output during transmit (bus is shared with TxDAC)
MSM7730
square wave (demodulation provides signal for carrier lock switch once preamble is detected
Oki Semiconductor
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MAC
Figure 6. MSM7730 Physical Layer Block Diagram
Convergence
Physical
Interface
Modem
Layer
-5
-5
BER (802.11 specifies sensitivity of 10
BER (802.11specifies sensitivity of 10
PHY Interface
Demodulator
Modulator
Control
Radio
RADIO
-5
-5
for 75 dBm)
for 80 dBm)