General Description - Realtek RTL8191SU User Manual

RTL8191SU
User's Manual

1. General Description

The Realtek RTL8191SU is a highly integrated single-chip MIMO wireless LAN (WLAN) solution for the
wireless high throughput 802.11n draft specification. It combines a MAC, a 1T2R capable baseband, and
RF in a single chip. The RTL8191SU provides complete solution for a high throughput performance
wireless client.
The RTL8191SU baseband implements multiple input, multiple output (MIMO) orthogonal frequency
division multiplexing (OFDM) with 1 transmit and 2 receive paths and is compatible with 802.11n Draft
specification 2.0. Other features include one spatial streams transmission, up to two spatial streams
reception, short guard interval (GI) of 400ns, spatial spreading, and transmission over 20 MHz and 40 MHz
bandwidth. At the receiver, extended range and good minimum sensitivity is achieved by having receiver
diversity up to 2 antennas.
For legacy compatibility, direct sequence spread spectrum (DSSS), complementary code keying (CCK)
and OFDM baseband processing are included to support all IEEE 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 the data rates of 1, 2, 5.5 and 11Mbps with
long or short preamble. The high speed FFT/IFFT paths, combined with BPSK, QPSK, 16QAM, and
64QAM modulation of the individual subcarriers and rate compatible punctured convolutional coding with
coding rate of 1/2, 2/3, 3/4, and 5/6, provides the maximum data rate of 54 Mbps and 300 Mbps for IEEE
802.11g and 802.11n MIMO OFDM respectively.
The RTL8191SU builds in an enhanced signal detector, an adaptive frequency domain equalizer, and a
soft-decision Viterbi decoder to alleviate the severe multi-path effects and mutual interference in the
reception of multiple streams. For better detection quality, receive diversity with maximal-ratio-combine
(MRC) applying up to 2 receive paths are implemented. Robust interference detection and suppression are
provided to protect against bluetooth, cordless phone, and microwave oven. Receive vector diversity for
multi-stream application is implemented for efficient utilization of MIMO channel. Efficient IQ-imbalance,
DC offset, phase noise, frequency offset and timing offset compensations are provided for the radio
frequency front-end impairments. Selectable digital transmit and receiver FIR filters are provided to meet
the requirement of transmit spectrum mask and to reject the adjacent channel interference, respectively.
The RTL8191SU supports fast receiver automatic gain control (AGC) with synchronous and asynchronous
control loops among antennas, antenna diversity functions, and adaptive transmit power control function to
obtain the better performance in the analog portions of the transceiver.
The RTL8191SU MAC supports 802.11e for multimedia applications, 802.11i for security, and 802.11n for
enhanced MAC protocol efficiency. Using packet aggregation techniques such as A-MPDU with BA and
A-MSDU, protocol efficiency is significantly improved. Power saving mechanisms such as U-APSD,
APSD, and MIMO power saving reduces the power wasted during idle time, and compensates for the extra
power required to transmit MIMO OFDM. The RTL8191SU provides simple legacy and 20Mhz/40Mhz
co-existence mechanisms to ensure backward and network compatibility.
4 Rev.1.0