User's Manual

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154
Therefore the “Ethernet” overhead is 100*1514/1460 = 3.7%
Additionally, there is an overhead associated with Airspan’s air interface. The data is
sent in small blocks, transmitted every 4ms on multiple RW channels simultaneously.
Additionally, an ST can receive up to 4 blocks simultaneously. Each block has a 4
byte overhead.
The number of bytes in a block depends on the modulation scheme being used, as per
the table below (showing the total bytes/block, including the 4 byte overhead):
Modulation
Total Bytes/Block
QPSK ½ 64
QPSK ¾ 96
16QAM½ 128
16QAM¾ 192
64QAM ¾ 288
As the Ethernet frame size is unlikely to be an exact multiple of the useable
Bytes/Block, there will be an additional overhead, as the block containing the last
section of an Ethernet frame will have some unused bytes, not completely filled by the
end of the frame.
Adding the overheads together results in the target throughput figures quoted in the
test plan. These numbers have been chosen as realistic figures that should be
achieved under laboratory test conditions.