User's Manual

Mobile WiMAX Indoor RAS SPI-2210 System Description/Ed.07

OFDMA Sub-carrier Allocation

The subchannelization is the process to tie the sub-carriers of OFDMA as a transmission

unit after grouping them by a certain rule. The indoor SPI-2210 performs the

subchannelization to mitigate the interference between cells.

The indoor SPI-2210 maps the column of the modulated downlink QAM symbol structure

with each sub-carrier and carries out the subchannelization when the column of the QAM

symbol structure is transmitted to the MS over the wireless line.

In such way, the indoor SPI-2210 transmits the column of the QAM symbol structure to the

MS via the sub-carriers pertained to each subchannel.

DL/UL MAP Construction

The indoor SPI-2210 informs the air resources for the uplink and the downlink to the MS

by using DL/UL MAP. The DL/UL MAP consists of the scheduling information of the

indoor SPI-2210 and includes various control information for the MS.

Power Control

The indoor SPI-2210 carries out the power control function for the uplink signal received

from multiple MSs and then set the power intensity of the uplink signal to a specific level.

The indoor SPI-2210 transmits the power correction command to each MS and then makes

the MS power intensity be the level required in the indoor SPI-2210 when the MS transmits

the modulated uplink signal in a specific QAM modulation method.

Hybrid-ARQ (H-ARQ) Operation

H-ARQ is the physical layer retransmission method using the stop-and-wait protocol.

The indoor SPI-2210 carries out the H-ARQ function and raises data throughput by re-

transmitting or combining the frame from the physical layer to minimize the effect

attending to the change of wireless channel environment or the change in the interference

signal level.

MIMO

The indoor SPI-2210 provides the MIMO function as follows according to Mobile WiMAX

Wave 2 Profile:

 Downlink

Matrix A (Space-Time Coding)

Transmission ratio of the Matrix A or Space-Time Coding (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 Signal to Noise Ratio (SNR) and provides excellent performance even

when the MS moves in high speed.

 Matrix B (Spatial Multiplexing, vertical encoding)

Matrix B or Spatial Multiplexing (SM) method raises the effectiveness of the

frequency by the number of antennas the transmission ratio in comparison with SISO.

This technology is effective when the reception SNR is high.