PRELIMINARY
Technical Description
ATPC is used to automatically adjust the transmit power P
out
in order to maintain
the received input level at the far-end radio at a target value. The received input
level is compared with the target value, a deviation is calculated and sent to the
near-end to be used as input for possible adjustment of the transmit power.
In ATPC mode, the transmit power P
out
varies between a selected maximum
level P
max
and a minimum level P
min
.
ECO mode is supported, and when ATPC mode is configured it is possible to
achieve a power consumption reduction with maintained performance.
3.3 Maximizing Radio Link Throughput
The maximum bit rate of incoming traffic on the LAN interface can be
significantly higher than the maximum bit rate over the radio link. For the radio
link to match the frame rate on the LAN interface, it is necessary to increase
the throughput on the radio link. This is done by stripping the IFG (interframe
gap) and preamble, and optionally by using multilayer header compression on
the Ethernet frames.
16782
Figure 5 Ethernet Packet and Frame Structure
Stripping the Preamble, SFD, and IFG
On the LAN side, the Layer 2 Ethernet data is encapsulated by a Layer 1
header consisting of an Preamble sequence, an SFD and an IFG. The IFG,
preamble and SFD are not needed in the traffic sent over the radio link. The
IFG and preamble are stripped from the packet, leaving only the Ethernet Layer
2 frame. A small overhead is added to the frame before it is sent over the
radio link. This way the traffic over the radio link consists almost entirely of the
payload, making it possible for the radio link to keep the same frame rate as
the LAN interface, even though the bit rate is lower.
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1/22102-HRA 901 17/9 Uen PU1 | 2016-07-04
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