User's Manual

5
For example, in the US, the maximum operating power should be limited as
follows:
Modulation
Max Output Power
QAM64 17 dBm
QAM16 20 dBm
QPSK, BPSK 23 dBm
Bandwidth Allows selection of the bandwidth (BW), in MHz, of the RF
network. Allowable options depend on your country of operation.
If a radio is likely to be installed in an area with other radios nearby, it is best
to use the 20 MHz bandwidth setting as this allows for more non-overlapping
channels. This is also the case if multiple radios are to be co-located on a
single tower or rooftop.
If maximizing throughput and distance is of primary importance, then it may be
best to use a larger bandwidth.
Both Master and Slave must share the same Bandwidth setting.
Frequency Allows selection of the center frequency of the RF link, based on
the model purchased, region of operation and operating bandwidth. The
Frequency parameter is available on Master PTP unit only. On a Slave unit, the
radio will search across the available channels in order to find the Master.
A sample frequency list for the XL5810 product as shipped in the US, is as
follows. Other models, including XL49 4.9 GHz versions will have
different center frequencies and available bandwidths.
Frequency
Bandwidth
5745 MHz 20 MHz
5765 MHz 20 MHz
5785 MHz 20 MHz
5805 MHz 20 MHz
5765 MHz 40 MHz
5805 MHz 40 MHz
Both Master and Slave must share the same Bandwidth setting.
Link Distance Should be set to the actual link distance, rounded up to the
nearest mile. This parameter is used to optimize the performance of the
SkyWay protocol across long distance links.
Note that the maximum link distance at 20 and 40 MHz bandwidths is 30mi
(48.3km) and 16mi (25.8km), respectively.
Modulation Used to establish the modulation and FEC rate of the OFDM/MIMO
radio. The higher the modulation setting (or “density”), the higher the link data
rate, but the lower the receive sensitivity.
From lowest to highest datarates, the available modulation/FEC settings are:
• BPSK- ½
• QPSK- ½
• QPSK- ¾
• QAM16- ½
• QAM16- ¾
• QAM64- ⅔
• QAM64- ¾
Streams The power of MIMO technology rests on the ability to define the
number of data streams that are carried across the multiple RF links. At all
times, the SkyWay link utilizes a 2x2 dual-chain MIMO format where 2 RF
transmit and 2 RF receive chains are enabled and active. However, these dual
chains can be used to carry 1 or 2 data streams.
In a 2 stream configuration, unique data is carried across each RF chain,
greatly increasing the amount of data capacity over a non-MIMO system. The
100 Mbps capability of the product requires that 2 streams operation be
configured.
In contrast, when increased link robustness and noise immunity is desired,
MIMO can be used in a 1 stream configuration. In this scenario, the same
information is carried across both RF chains, increasing the reliability of
reception.
It is recommended that both Master and Slave units share the same Modulation
and Stream settings.