User's Manual
CHAPTER 2. System Overview
2-4
© SAMSUNG Electronics Co., Ltd.
Hybrid-ARQ (H-ARQ) Operation
H-ARQ is the physical layer retransmission method using the stop-and-wait protocol.
The SPI-2L10 carries out the H-ARQ function to minimize the effect attending to the
change of wireless channel environment.
MIMO
The SPI-2L10 provides the MIMO function as follows according to Mobile WiMAX Wave
2 Profile:
y Downlink
− Matrix A (STC)
Transmission ratio of the Matrix A or STC is 1 and equal to that of Single Input
Single Output (SISO). However The Matrix A or the STC reduces the error of the
signal received from the MS by raising the stability of the signal received from the
MS by means of the Tx diversity. This technology is, also, effective in low Signal
to Noise Ratio (SNR) and provides excellent performance even when the MS
moves in high speed.
− Matrix B (SM, vertical encoding)
Matrix B or SM method raises the effectiveness of the frequency by raising the
transmission ratio in proportion to the number of antenna in comparison with SISO.
This technology is effective when the reception SNR is high.
y Uplink
− Collaborative SM
Collaborative SM is the technology that doubles the frequency efficiency in view
of the SPI-2L10 as two MSs with each individual antenna send data
simultaneously by using the same channel.
Adaptive MIMO Switching(SM/STC)
The SPI-2L10 provides the adaptive MIMO switching function which selects the SM or
STC method dynamically for the downlink MIMO function. The SPI-2L10 performs
switching based on a value calculated by reflecting the Carrier to Interference and Noise
Ratio (CINR) and transmission success rate sent by an MS.