User guide

45 Mbps Backhaul User Guide
Issue 3, December 2004 Page 106 of 113
12 FAQs
Can I source and use my own PoE adaptor with the 45 Mbps Backhaul? No. The 45 Mbps Backhaul uses a non-
standard PoE configuration. Failure to use the Motorola supplied Power Indoor Unit could result in equipment
damage and will invalidate the safety certification and may cause a safety hazard.
Why has Motorola launched the 45 Mbps Backhaul? The 45 Mbps Backhaul is the first product in this band to
feature Multi-beam Space Time Coding. The 45 Mbps Backhaul allows wireless connections of up to 130km
(81 miles) in near Line-of-Sight conditions and up to 10km (6 miles) in deep non-Line-of-Sight conditions.
What is Multi-beam Space-Time-Coding? The 45 Mbps Backhaul radiates multiple beams from the antenna -
the effect of which is to significantly protect against fading and to radically increase the probability that the
receiver will decode a usable signal. When the effects of Space-Time-Coding are combined with those of
OFDM techniques and a best in class link budget, there is a significant improvement to the probability of a
robust connection over a non-Line-of-Sight path.
What do you mean by “non-Line-of-Sight”? A wireless connection between 2 points without optical
Line-of-Sight. i.e. with obstructions in between the antennas but the transmitted signal is still able to reach the
receiver and produce a good quality link.
What else is special about the 45 Mbps Backhaul? There are many special features built-in to the hardware of
the 45 Mbps Backhaul. The product offers the highest system gain in its class through high sensitivity antennae
for improved signal recovery. It also features a Software Defined Radio system that operates on ultra fast digital
signal processors but is controlled by firmware giving the ability to download new firmware when
enhancements become available. The 45 Mbps Backhaul has a built-in web server for advanced management
capabilities including detailed radio signal diagnosis.
In which frequency band does the 45 Mbps Backhaul operate? The Motorola 45 Mbps Backhaul operates in the
unlicensed ISM band at 5.725!-!5.850GHz. This means no license is required to operate the 45 Mbps Backhaul.
Why does the 45 Mbps Backhaul operate in the 5.8GHz ISM band? The 5.8GHz band offers the dual benefits of
high data throughput and good radio propagation characteristics. The wide band of spectrum available is
subdivided into several channels such that multiple systems can operate in the vicinity without causing
interference to one another.
Is the 45 Mbps Backhaul an 802.11a device? No, although similar, the 45 Mbps Backhaul uses different
encoding and radio transmission systems than 802.11a. In areas where 802.11a systems are operating, the 45
Mbps Backhaul will detect the 802.11a radio signals and choose a clean channel away from any interference.
How much power does the 45 Mbps Backhaul transmit? At all times the 45 Mbps Backhaul operates within
country / region specific regulations for radio power emissions. In addition, the 45 Mbps Backhaul uses a
technique known as Transmit Power Control (TPC) to ensure that it only transmits sufficient radio power such
that the other antenna can receive a high quality signal.
How does the 45 Mbps Backhaul avoid interference from other devices nearby? At initialization, the 45 Mbps
Backhaul monitors the available frequency channels to find a channel that is clean from interference. In
operation 45 Mbps Backhaul continuously monitors the spectrum to ensure it is operating on the cleanest
channel.
How does the 45 Mbps Backhaul integrate into my data network? The 45 Mbps Backhaul acts as a transparent
bridge between two segments of your network. In this sense, it can be treated like a virtual wired connection
between the two buildings. The 45 Mbps Backhaul forwards 802.3 Ethernet packets destined for the other part
of the network and filters packets it does not need to forward. The system is transparent to higher-level
management systems such as VLANs and Spanning Tree.
How does the 45 Mbps Backhaul provide security for data traffic? The 45 Mbps Backhaul has a range of
security features. At installation time each link must be programmed with the serial ID of its partner. The two
ends of the link will only communicate with one another, eliminating any chance of "man in the middle"