1.General Description
The Realtek RTL8812FR-CG is a highly integrated single-chip that support 2-stream 802.1lac solutionswith Multi-user MIMO (Multiple-Input，Multiple-Output) with Wireless LAN (WLAN) PCI Expressnetwork interface. It combines a WLAN MAC, a 2T2R capable WLAN baseband, and RF in a single chip.
The RTL8812FR-CG baseband implements Multi-user Multiple Input， Multiple Output (MU-MIMO)Orthogonal Frequency Division Multiplexing (OFDM) with two transmit and two receive paths (2T2R).Features include two spatial stream transmissions, short Guard Interval (Gl) of 400ns, spatial spreading,and support for variant channel bandwidth. Moreover，RTL8812FR-CG provides one spatial streamspace-time block code(STBC),Transmit Beamforming(TxBF) and Low Density Parity Check (LDPC) toextend the range of transmission.At the receiver, extended range and good minimum sensitivity is achievedby having receiver diversity up to 2 antennas.As the recipient, the RTL8812FR-CG also supports explicitsounding packet feedback that helps senders with beamforming capability.
For legacy compatibility, Direct Sequence Spread Spectrum(DSSS),Complementary Code Keying(CCK)and OFDM baseband processing are included to support all IEEE 802.11b,802.11g and 802.11a data rates.Differential phase shift keying modulation schemes,DBPSK and DQPSK with data scrambling capabilityare available, and CCK provides support for legacy data rates, with long or short preamble.The high speedFFT/IFFT paths，combined with BPSK,QPSK，16QAM,64QAM and 256QAM modulation of theindividual subcarriers, and rate compatible coding rate of 1/2,2/3,3/4, and 5/6, provide up to 866.7Mbpsfor IEEE 802.11ac MIMO OFDM.
The RTL8812FR-CG builds in an enhanced signal detector, an adaptive frequency domain equalizer, and asoft-decision Viterbi decoder to alleviate severe multi-path effects and mutual interference in the receptionof multiple streams. For better detection quality, receive diversity with Maximal-Ratio-Combine(MRC)applying up to two receive paths, and Maximum-Likelihood Detection (MLD) are implemented.Robustinterference detection and suppression are provided to protect against Bluetooth,cordless phone, andmicrowave oven interference.
