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FAQs -
Client Equipment
What antennas should I use for my clients (CPE)?
This depends upon the hub antenna, cable type and length,
distance, data rate and terrain. You should test your
system first before a final antenna selection. For WISP systems
using +36 dBm EIRP at the AP and clear LOS, use the following
table as a guide:
Distance (miles) |
CPE antenna gain |
0.5 - 2 |
7 - 9 dBi |
2 - 5 |
9 - 15 dBi |
5 - 7 |
15 - 20 dBi |
7 + |
20 - 24 dBi |
How
can I route coaxial cable into a customer's house?
Whatever you do, do NOT drill through his roof. This will
ultimately cause leaks. Most installers route the cable to
a wall location below the eaves and drill a hole just large
enough for the cable to enter. Ideally, the inside coaxial
connector should be installed after the cable is installed.
Seal the wall entry from water using a silicon-based sealant.
The best installation uses existing holes or a basement wall
entry, however sometimes this is not available or practical.
Is the Customer or Client (CPE) system considered PtMP
or PtP?
If the CPE system (or Subscriber Unit - SU) only talks with
the POP/AP and is at a fixed location, then it is considered
to be PtP and can use power and antenna gain associated with
PtP systems, as shown below. (This has been verified by FCC Certified
systems using a 26 dBm radio and a 17 dBi antenna) If a CPE
system is part of a mesh network, then it is considered PtMP.
How does Fragmentation Threshold work in the CPE?
Fragmentation
Threshold adjustment may be required to increase the reliability
of frame transmissions. This value determines the size at
which packets are fragmented. (sending the packet as several
pieces rather than one block) The 2473 CPE has a default value
of 2346, which will work most of the time. Occasionally, when
there is interference, this value should be lowered to improve
efficiency and reduce packet loss.
How does RTS Threshold work in the CPE?
RTS/CTS
adjustment may be required to minimize collisions among hidden
nodes. This value determines the packet size at which the
CPE issues the request to send (RTS) before sending a packet.
The default value of 2347 works most of the time, however
a low RTS setting may improve the throughput when many client
devices are associating with an AP or when the clients are
far from each other and can only detect the AP and not each
other. This setting should be adjusted before trying to change
the fragmentation threshold.
What steps can I take to enhance security?
First,
change the AP's SSID from the default that is set at the factory.
Second, make the AP's SSID invisble (turn off the SSID broadcast).
Implement a password for access to the AP and CPE configuration
software. Enable MAC address filtering in the AP. Enable 128
bit WEP with open key authentication. Deny unencrypted data
in WEP. Change the WEP keys at least weekly. Disallow administrative
access over wireless. Use secure protocols such as VPN connections
or SSH (secure shell) or SSL (secure sockets layer). MAC filtering
won't actually deny association, it just won't pass any traffic
from a non-authorized MAC address. A good measure to implement
at the next hop past the wireless nextwork is IP/MAC pair
filtering. A LINUX box with iptables can do this by creating
a chain which gets all traffic from X.X.X.X/X.X.X.X processed
by a chain which only allows traffic from MAC x:x:x:x:x:x.
Is Shared Key Authentication better than Open Key in
WEP?
Shared
Key Authentication is not considered secure, because a hacker
who detects both the clear-text challenge and the same challenge
encrypted with a WEP key can decipher the WEP key. With Open
Key Authentication, even if a client can complete authentication
and associate with an AP, the use of WEP prevents the client
from sending data to and receiving data from the AP, unless
the client has the correct WEP key.
How can I prevent inter-client file sharing in my WISP?
We recommend
that all wireless clients use a NAT router between the CPE
and their computers. This will block all NETBIOS traffic and
also supply the customer with limited firewall protection
against hackers and broadcast based viruses.
Find
answers to any of your qustions by contacting our experienced
Consulting Team providing professional
services to the developing technological world.
Technical
FAQ Categories
Basics,
Access
Point, Antenna Properties,
Canadian RSS-210, Client
Equipment, FCC Part 15, Point
to Multi-Point, Point to Point,
Pre-installation and Site Preparation,
Radio Propagation, Reference
Material, Troubleshooting.
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