Realtek Wireless LAN RTL8187L

The Realtek RTL8187L, fully complying with IEEE 802.11a/b/g

specifications, is a low-profile highly integrated cost-effective

Wireless LAN USB 2.0 network interface controller that integrates a

USB 2.0 PHY, SIE (Serial Interface Engine), 8051 MCU, a Wireless

LAN MAC, and a Direct Sequence Spread Spectrum/OFDM baseband

processor onto one chip. It provides USB high speed (480Mbps), and

full speed (12Mbps), and supports 4 endpoints for transfer pipes.

To reduce protocol overhead, the RTL8187L supports Short InterFrame

Space (SIFS) burst mode to send packets back-to-back. A protection

mechanism prevents collisions among 802.11b nodes.

Direct Sequence Spread Spectrum (DSSS), Complementary Code Keying

(CCK), and Orthogonal Frequency Division Multiplexing (OFDM)

baseband processing are implemented to support all IEEE 802.11a,

802.11b, and 802.11g data rates.

Differential phase shift keying modulation schemes, DBPSK and DQPSK

with data scrambling capability, are available, along with

complementary code keying to provide data rates of 1, 2, 5.5, and

11Mbps, with long or short preamble. A high-speed Fast Fourier

Transform (FFT)/Inverse Fast Fourier Transform (IFFT), combined

with BPSK, QPSK, 16QAM and 64QAM modulation of the individual

sub-carriers, provides data rates of 6, 9, 12, 18, 24, 36, 48 and

54Mbps, with rate-compatible punctured convolutional coding with a

coding rate of 1/2, 2/3, and 3/4.

An enhanced signal detector, an adaptive frequency domain

equalizer, and a soft-decision Viterbi decoder are built-in to

alleviate severe multipath effects. Efficient IQ-imbalance

calibration, DC offset, phase noise, frequency offset, and timing

offset compensation reduce radio frequency front-end impairments.

Selectable digital transmit and receiver FIR filters are provided

to meet the requirements of transmit spectrum masks, and to reject

adjacent channel interference, respectively.

Both in the transmitter and receiver, programmable scaling in the

digital domain trades the quantization noise against the increased

probability of clipping. Robust signal detection, symbol boundary

detection, and channel estimation perform well at the minimum

sensitivity.

The RTL8187L supports fast receiver Automatic Gain Control (AGC)

and antenna diversity functions, and an adaptive transmit power

control function to obtain better performance in the analog

portions of the transceiver. It also has on-chip digital-to-analog

converters and analog-to-digital converters for analog I and Q

inputs and outputs, transmit TSSI and receiver RSSI inputs, and

transmit and receiver AGC outputs.

The RTL8187L is highly integrated and requires no 'glue' logic or

external memory. It keeps network maintenance costs low and

eliminates usage barriers.