Introduction

The WISP (Wireless ISP) base station design and CPE (customer premises equipment) is for reference purposes only. It is your responsibility to follow any FCC regulations, and it is highly suggested that you retain the services of a qualified engineer before attempting any radio and/or customized WiFi installations.

Specifications

The specifications are separated into three sections: Base station, Unobstructed CPEs (customer premises equipment), and Obstructed CPEs (limited obstructions such as trees and wires).

There are also several appendices at the end of this document including a list of definitions (Appendix A.)

Base Station

The base station is designed to have a 1.5 mile radius for unobstructed connections (longer distances are possible with alternate CPEs) and a theoretical 1 mile radius for obstructed connections. The basic base station will have one access point and use one channel. Two and three channel configurations will also be possible.

Obstructions, which include significant tree growth, are somewhat variable and will need significant testing. The base station configuration may also includes the NLOS (non-line-of-site) TurboCell software from Karlnet.

The entire base station cost is around $3,500 to $6,500 depending on vendors and configuration.

Item/Value	Spec	Comments
Equipment location	Inside	cost savings and ease of installation of an inside equipment installation outweigh cost of amplifiers and coax cables.
Channels/Access Points	One, two, and three channel options.	The basic base station will have one chanel/one AP. Another channel can easily be added as the main AP will have two card slots. A third channel would require another AP box.
Equipment casing	In one box	Note that all three possible channels should be wired to the outside of the box even if only one or two channels are used. The casing box should also allow easy installation of additional channel equipment. Basically, additional channel equipment (including an additional AP for the third channel, amplifier power injectors, and external N-Female connectors, as well as power connectors) should fit into a slot and/or be attached by screws.
Equipment Type	Agere chipset	Used in Avaya, Agere, Lucent, and Proxim.
Enhanced AP Firmware	Yes	Karlnet TurboCell. See "Karlnet TurboCell" section below for more information. Adds $399 to cost of each base station unit.
NLOS Hardware	No	NLOS hardware is too expensive and very proprietary.
Transmitter strength	At least 30 mW	Will be amplified to 400 mW.
Antenna(s)	One three sector antenna.	Three 120° sectors. Maxrad Sectorized Omni-directional antenna.
Antenna degrees	Each sector 120°
Vertical beam width	9°	Dependent on gain and sector size. Sector antennas with gains higher than 15 dBi have very short vertical beam widths reducing possible coverage.
Polarization	Vertical	We may still need to consider horizontal. Horizontal provides the least amount of interference and propagates through trees better, however, horizontally polarized anntenas are more expensive, larger, and harder to come by.
Wattage at antenna	4 Watts EIRP (actually 3.32 in 1 channel configuration)	This is the maximum allowed by the FCC. See "Base Station Wattage Maximization" below.
Input Tx strength	400 mW (26 dBm)	Note that in the basic one channel configuration the power will be split into 133 mW per sector.
Antenna gain	14 dBi
Receive sensitivity	-95 dBm	This high level of receive sensitivity due to smart amplifier.
Amplifier type	One channel: One 400 W Two channel: One 300 W, and One 150 W Three channel: Three 150 W Outside smart bi-directional external	Should include DC power injector so that it can be powered over the coax cable. One amplifier and injector are necessary per channel.
Receive bandpass filter	Yes	This removes out-of-band receive emissions and which decreases distortion and interference. This should, ideally be included in the amplifier and should be adjustable in 20 mHz increments or, ideally, should occur automatically (as in the YDI amps.)
Coax cable type	LMR600	LMR400 could be used as the attenuation is only marginally higher, however, LMR400 adds significantly more noise.
Cable length	125'	This length should allow inside installation of all base station equipment for almost all installations. Note that no installations should use cable shorter than this as this can create excess wattage problems. For example a 25' cable using these specs would have a Tx EIRP of 11 Watts (far over the FCC limit.)
Coax cable attenuation	5.56 dB	0.0445 / foot. Since the amplifier will be place externally near the antenna the cable loss attenuation can be factured out of the EIRP calculation, however, the cable length can add a small amount of noise.
Wireless protocol	802.11b	802.11a is a possibility, however, the costs are still to high, and there is only limited equipment available.
802.11b channels	One chanel: 11 Two chanels: 11,6 Three channels: 11, 6, 1	These are the three non-overlapping 802.11b channels.
Spectrum Spread	DSSS	802.11b uses DSSS (direct sequence spectrum spread). The alternative is FHSS (frequency hoping spectrum spread). FHSS is more NLOS, and can handle significantly more connections, however, it is much more expensive.
Antenna mast length	At least 19' above nearby houses and other obstructions.	The higher the better, however, 36' is really the maximum mast installable by a non-professional.
Configuration interface	Network interface and serial	Include serial cable + adaptor to terminate with standard DB9 or DB25 serial cable.
Encryption	128 bit WEPplus	This is not meant to be ironclad security. WEPplus is automatic if Agere based RF radios using firmware 8.00 or higher are used.
MAC Address Authentication	Yes
Additional authentication/encryption	Possible 802.1X, Radius, VPN, IPSec.	This may or may/not be necessary. We should only provide a reasonable, yet low level of encryption/security. The end-user should be aware that they are solely responsible for the security of their own systems.
"Closed" vrs. "Open" network	Closed	Setting most access points to "Closed" will disable access from clients set to the network "ANY". This makes it harder, though certainly not impossible, for scanners such as Netstumbler to find the base station/access point.
Lightning protection	Yes	Mast and coax protectors. Amplifier should have internal lighthning protection.
FCC Certification	See comment	Within FCC limits, however, the full assembly would not be officially FCC certified.

Base Station Wattage Maximization

FCC Regulations allow up to 4 Watts EIRP (Effective Isotropic Radiated Power) for point-to-multipoint applications (using omni directional or sector antennas) in the 900 MHz, 2.4 GHz, and 5.8 GHz bands.

The transmitters in WLAN equipment are usually 20, 30, or 100 mW. Any one of the WLAN transmitters can be used with a combination of amplifiers and antenna gain (though 30 mW or higher is preferred). The WLAN equipment should not be chosen based on mW, but on features and RF circuitry sensitivity, error-control, and NLOS capabilities.

All of the standard mW levels can be increased through gain and amplification to the FCC maximum. Based on the WLAN equipment choice, the cable length, and the vertical beam width the gain and amplification can be modified to maximize the Tx EIRP to the 4 Watt FCC maximum.

Tx Power is transmitter + amplifier. Smart amplifiers amplify to specified Tx (and Rx) rather than simply adding amplification. Since there will be three base station configurations (1 to 3 channels) three amp types will be needed. For a single channel system one 400 mW amp will be used (splitting to three 133 mW segments.) For a two channel system on 300 mW (spltting into two 150 mW segmants) and one 150 mW amps will be used. For a three channel system three 150 mW amps will be used.

Splits	Tx mW	Tx mW ( / splits)	Antenna Gain (dBi)	EIRP (in Watts)
3	400	133	14	3.32
2	300	150	14	3.73
1	150	150	14	3.73

Karlnet TurboCell

TurboCell is a group of wireless operating systems and firmware upgrades to Agere chipset based WiFi products. Most significantly it adds some NLOS capabilities that allow operation in lower LOS (line-of-site) settings. It also adds the following features:

Feature	Comments
Bandwidth control and throttling	Bandwidth control is essential and with TurboCell it would not need to be provided by other means.
RADIUS authentication & accounting	Adds a level of authentication stronger than MAC address control and can be used to authenticate make to a central database, and we wouldn't need to ad this to the Linux box
Additional authentication and licensing capabilities	Integrated with bandwidth control
Node capacity of 64	With standard 802.11b there is usually a 32 node maximum.
Firewall & DHCP/NAT
New in version 4.02 --> Support for 802.11b clients
Superpacket Aggregation and Adaptive Dynamic Polling	This significantly lowers broadcast and collision problems
Routing	This is important for larger installations.

Linux System

The linux box will be used for the T1 line connection using an internal T1 and CSU/DSU card, control bandwidth, monitor the network, as well as access control.

Feature	Spec	Comments
Linux box size	Small	Should be as small as possible but allow at least three PCI slots
T1 Card	Standard T1 card	With Iinternal CSU/DSU.
Ethernet Card	10/100 mbs	On motherboard.
Default Queing	Stochastical Fairness Queueing	Keeps anyone connection from overloading T1 line.
Traffic shaping	192k per connection	Consumer class level held at 192 k. Business class by network segment and set to allocated size. Some protocols should be allowed to go above the 192k limit for a small amount of time. For example http connections should scale to the full T1 speed for short periods of time. The main traffic shapping will scale back to the CIR rate when a longer connection occurs (long being more than a few seconds.) Traffic shapping will be bi-directional (that is the outdoing interface to the T1 line will control outgoing traffic, and the outgoing interace to the wireless network will control incoming traffic.)
Traffic shaping queing mechanism		HTB http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm
Monitoring system	Netstaint and MRTG
Admistrative interface	Web based	Built in-house. Will only have a small number of features to configure T1-line and networking information. Fully-featured interface may be necessary immeadiately if separate business class service isn't offered and all connections are treated indentically.
Routing	Standard Linux routing
Remote access	SSH
Authentication	Radius (possibly with 802.1X)	Possible radius server authentication to allow and control access. May not be necessary as this is generally only necessary in a hotspot configuration. This could be used in conjuntion with a VPN connection as well as the traffic shaping mechanism. This authentication may or may not connect back to a central radius server.
DHCP Server	Yes	Possible one IP address per CPE restriction. How this can be accomplished not sure at thi spoint.
DNS Server	Yes	Should create secondary DNS server outside of Linux box (back at co-location).
Serial cable	Not included	Configuration will boot to default IP address and will be configurable through LAN interface. Configuration through a serial cable will still be possible, though.
Keyboard and monitor inclusion	Not included	Own monitor and keyboard will need to be purchased or provided separately, however, all configuration should take place through the serial and LAN port.

Unobstructed CPE

The Unobstructed CPE is designed for 1.5 mile radius full line-of-site connections (though it should work with some shorter distance obstructed connections.)

Item/Value	Spec	Comments
Equipment location	Outside	In panel antenna with inside PoE power injector.
Equipment Type	Agere chipset	Used in Avaya, Agere, Lucent, and Proxim.
Enhanced firmware	Not determined	Karlnet TurboCell possible. See "Karlnet TurboCell" section below for more information. Adds $65 to cost of CPE.
NLOS Hardware	No	NLOS hardware is too expensive and very proprietary.
Transmitter strength	30 mW
Antenna	Panel antenna
Antenna beam width	15°
Polarization	Vertical	We may still need to consider horizontal. Horizontal provides the least amount of interference and propagates through trees better, however, horizontally polarized anntenas are more expensive, larger, and harder to come by.
Wattage at antenna (EIRP)	1.89 Watts EIRP	This is below the EIRP maximum of 25 Watts for an 18 dBi gain directional antenna.
Input Tx strength	30 mW	No amplifier required
Antenna gain	18 dBi
Receive sensitivity	-82 dBm
Amplifier type	None
Coax cable type	None	CPE unit in antenna
Coax cable connectors	N/A
Ethernet Cable length	25' and 100' option	Longer cable lengths should be available.
Coax cable attenuation	N/A
Cable connectors (outside cable)	N/A
System pigtail	N/A
Ethernet cables	Standard outdoor cable	Has special connector to CPE/Antenna
Wireless protocol	802.11b	802.11a is a possibility, however, the costs are still to high, and there is only limited equipment available.
Spectrum Spread	DSSS	802.11b uses DSSS (direct sequence spectrum spread). The alternative is FHSS (frequency hoping spectrum spread). FHSS is more NLOS, and can handle significantly more connections, however, it is much more expensive.
Antenna mount	Poll or wall mount	Only provide one or the other in each CPE package.
Antenna mast length	No mast	As long as LOS possible. Small mast may sometimes be necessary to achieve LOS. This should be avoided, though, as the CPE price will increase.
Lightning protection	None (unless there is a mast)	Mast (if necessary) and coax protectors. A mast requires lighting protection. This will increase costs.
FCC Certification	See comment	Within FCC limits, however, the full assembly would not be officially FCC certified.

Unobstructed CPE Cost

The cost of a full CPE with antenna mounted equipment has fallen bellow $400 and with volume purchases the price should be around $350 / CPE (Though this is a somewhat aggressive estimate and a price of $370 or higher is more likely).

Here is a breakdown of the costs.

Item	Cost	Comments
Orinoco RG-1100 Residential Gateway or equivalent	$215.00	Mounted in or on antenna.
TurboCell SOHO for RG-1100 (1-user)	N/A
18 dBi Panel Antenna	$60.00
Mounting kit	$20.00	Wall or poll mount (does not include poll or mast)
25' ethernet	$55.00	25 feet is actually a somewhat short cable run.
TOTAL	$350.00	This is a somewhat aggressive estimate and a price of $370 or higher is more likely Add $39 for a 100' cable for a total price of $389.

Obstructed CPE

The unobstructed CPE is designed for 1 mile radius none-line-of-site connections including partial obstructions and trees. Full testing will be necessary to determine actual NLOS capabilities as attenuation due to obstructions is difficult determine without actual location tests.

Item/Value	Spec	Comments
Equipment location	Outside	In panel antenna with inside PoE power injector.
Equipment Type	Agere chipset	Used in Avaya, Agere, Lucent, and Proxim.
Enhanced firmware	Not determined	Karlnet TurboCell possible. See "Karlnet TurboCell" section below for more information. Adds $65 to cost of CPE.
NLOS Hardware	No	NLOS hardware is too expensive and very proprietary.
Transmitter strength	30 mW
Antenna	Panel antenna
Antenna beam width	15°
Polarization	Vertical	We may still need to consider horizontal. Horizontal provides the least amount of interference and propagates through trees better, however, horizontally polarized anntenas are more expensive, larger, and harder to come by.
Wattage at antenna (EIRP)	15.77 Watts EIRP	This is approaching the maximum 25 Watts for an 18 dBi gain directional antenna.
Input Tx strength	30 mW
Antenna gain	18 dBi
Receive sensitivity	-82 dBm
Amplifier type	250 mW
Coax cable type	None	CPE unit in antenna
Coax cable connectors	N/A
Ethernet Cable length	25' and 100' option	Longer cable lengths should be available.
Coax cable attenuation	N/A
Cable connectors (outside cable)	N/A
System pigtail	N/A
Ethernet cables	Standard outdoor cable	Has special connector to CPE/Antenna
Wireless protocol	802.11b	802.11a is a possibility, however, the costs are still to high, and there is only limited equipment available.
Spectrum Spread	DSSS	802.11b uses DSSS (direct sequence spectrum spread). The alternative is FHSS (frequency hoping spectrum spread). FHSS is more NLOS, and can handle significantly more connections, however, it is much more expensive.
Antenna mount	Poll or wall mount	Only provide one or the other in each CPE package.
Antenna mast length	No mast	As long as LOS possible. Small mast may sometimes be necessary to achieve LOS. This should be avoided, though, as the CPE price will increase.
Lightning protection	None (unless there is a mast)	Mast (if necessary) and coax protectors. A mast requires lighting protection. This will increase costs.
FCC Certification	See comment	Within FCC limits, however, the full assembly would not be officially FCC certified.

Obstructed CPE Cost

The obstructed CPE includes a $200 amplfier, but basically all the componets are the same as the unobstructed CPE.

Item	Cost	Comments
Orinoco RG-1100 Residential Gateway or equivalent	$215.00	Mounted in or on antenna.
Amplifier	$200.00
TurboCell SOHO for RG-1100 (1-user)	N/A
18 dBi Panel Antenna	$60.00
Mounting kit	$20.00	Wall or poll mount (does not include poll or mast)
25' ethernet	$55.00	25 feet is actually a somewhat short cable run.
TOTAL	$550.00	This is a somewhat aggressive estimate and a price of $570 or higher is more likely Add $39 for a 100' cable for a total price of $589.

CPE Station Wattage Maximization

According to FCC regulations, 2.4 GHz Part 15.247 point-to-point (PtP) transmitters may use a 30 dBm transmitter with a 6 dBi antenna. For a 3 dB increase in antenna gain, the transmitter power output must be reduced by 1 dB. Power is measured at the antenna connector, so subtract any cable loss between the amplifier and the antenna.

Power at antenna (dBm/watts)	Max Antenna Gain (dBi)	EIRP (dBm)	EIRP (watts)
30 dBm (1 W)	6	36	4
29 dBm (800 mW)	9	38	6.3
28 dBm (630 mW)	12	40	10
27 dBm (500 mW)	15	42	16
26 dB