Motorola MOTOwi4 Canopy 30, User Manual

Page: 25 / 162

Issue 3.1, July 2006 Page 25 of 162
4 Product Architecture
The Canopy 30/60 Mbps Backhaul consists of an identical pair of units deployed one at each
end of the link. The radio link operates on a single frequency channel in each direction using
Time Division Duplex (TDD). One unit is deployed as a master and the other as a slave. The
master unit takes responsibility for controlling the link in both directions.
The non-Line-of-Sight (NLOS) aspects of the product are provided by multi-beam space time
coding, coupled with Orthogonal Frequency Division Multiplex (OFDM) modulation.
The 30/60 Mbps Backhaul has been developed to operate within license exempt frequency
bands.
The current product range supports:
ETSI 5.4 GHz band B (5.470-5.725 GHz)
ETSI 5.8 GHz band C (5.725-5.850 GHz) and the USA 5 GHz ISM band (5.725-5.850 GHz)
The 30/60 Mb BH has been designed to coexist with other users of the band in an optimal
fashion using a combination of Transmit Power Control (TPC), Planned Frequency Allocation,
or Dynamic Frequency Selection (DFS) and Antenna beam shape.
In order to maintain link availability, the product employs adaptive modulation techniques that
dynamically reduce the data rate in severe or adverse conditions. To the data network the
30/60 Mbps Backhaul is implemented as a learning bridge. A learning bridge builds up a picture
of which addresses are connected to which port. This means that it will not bridge a packet if it
knows that the destination address is connected to the same port on which the bridge saw the
packet.
Figure 10 illustrates the 30/60 BH layer diagram.
Figure 10: 30/60 Mbps Backhaul Layer Diagram
The 30/60 Mbps Backhaul functionality has been extended to encompass the specification
IEEE 802.1p. IEEE 802.1p uses Ethernet packets extended by 4 bytes, as specified in IEEE
802.1q for VLAN tagging, to prioritize packets over the wireless interface. The 30/60 Mbps
Backhaul will forward all VLAN tagged packets regardless of the VLAN ID value.
Each unit in the link is manageable through an IP connection. Standard IP protocols are utilized
for all management functions e.g. HTTP, SNMP, etc.