WIFI PLANNING

Deploying a wireless LAN is a considerable undertaking. Significant planning is required and that's not simply a matter of identifying user locations and connecting them to the backbone. Wireless LANs provide mobility through roaming capabilities and as such have limited range. A typical Wireless access device or router can broadcast or receive information with a 300 ft. radius, indoors, and may extend this to 800-1000 ft., outdoors. Beyond that, additional hardware is required. In addition, obstructions and metal enclosures may reduce the effective range of the signal.

Understand your Environment

The one most important thing before deploying any wireless solution is a SITE
SURVEY - this cannot be emphasized enough. Get a diagram/ layout of the building
and place an AP at a potential deployment location. Then walk around the area with a
wireless sniffer program (one such program is Network Stumbler www.netstumbler.com), reading the wireless signal-to-noise ratio and signal readings at each location. This
will show what kind of coverage area that one AP has at that point. Then move the AP to a different location and continue the survey. The AP does not need to have an Internet connection for the site survey. Do this for all potential locations and then adjust placements of APs based on your results. Remember to test between floors as well since the wireless signal is not usually confined in one floor but may provide adequate coverage in floors above and below the AP. Usually coverage of one AP is 4-6 rooms on a floor, and in some cases where the AP has adequate coverage between floors, you can get 12-18 rooms covered with 1 AP.

Keep in mind that APs will not work well passing through more than 2-3 walls depending on the make of the wall. In some cases, you can count the floor as one wall.

Understand your Access Point (AP)

Understand what the power output of the radio is (in dBm) and the gain of your antennas (dBi).

A 15dBm radio + 2dBi Antenna makes for an output of 17dBm.

To convert milliwatts to dBm:

dBm = 10 * (log (1000 * P))
P = Power in Watts
1000mW = 1 Watt

To convert dBm to milliwatts:

P = 0.001 * (10**(dBm/10))
P = Power in Watts

Please remember, FCC regulations have a 1 WATT (30dBm) limit on omni directional antennas and 2 WATT (33dBm) limit on directional antennas. Violating these guidelines may result in FCC fines.

Understand your antenna selections

The output shape and gain of your antenna selected is important to know and understand in order to deploy and use them correctly and effectively. Omni directional antennas broadcast in a 360˚ spread around the length of the antenna – like a donut with a stick in the center. When looking at the antenna from above, where the doughnut hole is, you will have a dead zone of coverage. These omni antennas are normally used for wide area access coverage, and are normally mounted upright for horizontal coverage. Directional antennas are usually higher in gain than omni directional because it focuses the signal into a beam, usually with a small degree of spread. These are used mostly in point-to-point applications over longer distances.

Note: Increasing power and gain will not necessarily solve a coverage problem; it will most likely cause interference to other APs you are deploying. Also, in areas where you do need a strong signal, you will ALSO need strong clients to communicate back to the AP. Because any communication is bi-directional, the client may be able to see the AP signal, but if the client is not as strong as the AP, it will never be able to communicate back to the AP properly. This point is very important. Also, the shape coverage of the antenna will determine how you align your antenna to get the coverage you want.

Some common wireless connectivity problems have to do with your distance from the antenna, as you’d expect. However, there are also certain places that can create problems with wireless connectivity. One such place is directly under a vertical antenna that is pointing upward. As mentioned earlier, an omnidirectional antenna has a doughnut-shaped area of coverage, which means that there’s a hole right in the middle. If you’re working in the area covered by the hole and you aren’t able to connect to the network, try moving your wireless device, moving your base antenna, or mounting the antenna upside-down on the ceiling instead. If you’re not using an omnidirectional antenna for your indoor client application, you should replace the directional antenna that you are using. If you’re using a directional antenna because of its increased range, just add a second access point to cover the same distance. In the long run, you’ll have a more efficient system in place, as well as better throughput from more areas.

To determine the best possible external antenna for your wireless LAN-to-LAN Bridge, please refer to the table below that outlines the relationship between antenna gains (dBi) and distances:

Try our free OMNI Antenna Beamwidth Analysis. The purpose of this tool is to illustrate how Omni and directional antennas work. We have found that many individuals miscalculate the signal strength they will receive by adding a high gain Omni antenna to their access point or gateway. This is because the higher the gain, the narrower the beam. Simply putting a high gain antenna on your roof may broadcast your signal several miles, but the signal my never touch the ground to reach your end-users located 10 or 20 feet from your antenna.

IMPORTANT NOTE: Most WiFi, 802.11b and 802.11g, antennas on the market today are linear (or vertically) -polarized. This includes the small, "rubber ducky" antennas that ship from the factory with most wireless devices.

A radio wave travels through the air about the size of a pine needle. If the antenna is vertically polarized the pine needle must remain vertical, as sent. If the signal hits an obstruction the signal will flip or rotate into multiple positions as it gets to the receiving radio's antenna where it will be seen as noise. The vertically-polarized antenna will not capture that signal. A multi-polarized antenna, one that sees rotating signal on all polarizations, will succeed at capturing that signal. Please see our line of multi-polarized, tree-penetrating antennas for these applications.

Understand end user client adapters

When testing in your survey, try using different adapters (built-in adapters, CardBus adapters, USB wireless adapters, etc.). This will best give you an accurate survey of what customers staying at the hospitality would be experiencing. Some surveyors use high-powered client cards, which then give them a false sense of adequate coverage.

Understand 802.11b/g Channels

When deploying APs, one thing to keep in mind is that APs nearest to each other should be set to non-overlapping channels (unless bridged). The ONLY theoretical non-overlapping channels are 1, 6, and 11. Any channels in between will overlap with one of these 3, causing interference and reduced bandwidth.

After the site survey, AP channel mapping can be done. Even if you use the non-overlapping channels (1, 6, and 11), if you have a strong enough AP on channel 1, you can actually cause interference on the other channels as well.

Example of the 802.11b/g spectrum: North America uses only Channels 1 through 11 (2.412Mhz – 2.462Mhz).

A successful deployment will only be successful if you invest the time in doing the site survey. Skipping this crucial step may and will almost definitely result in costly changes that are needed to be made later on when problems start arising during normal use. This leaves a bad impression and lessened confidence from the hospitality owner. Taking the time and effort in the beginning will be worth while in the long run.

Customer Privacy & Security

One of the most important aspects of providing Internet in a hospitality environment is customer security and privacy. Basically, the customer should be able to use Internet service without fear of someone having unauthorized access to his or her computer, and without someone spying on the data he or she is transmitting. This is especially true in a hospitality environment, where customers broadcast their traffic to access points before line security is established.

There are three types of security in a wireless hospitality setup: authentication, wired security, and wireless security.

Authentication: Authentication ensures that only guests and customers are using the wireless Internet service. Authentication is usually done via a username & password method.

Wired Security: Typically, when all users use the same infrastructure to connect to the Internet, they can see each other’s computers and other shared network resources. Switches that have Virtual LAN (VLAN) capabilities, however, allow each port to be treated like its own private network, ensuring privacy between each customers' connection.

Wireless Security: Wireless users share the same problem as wired users when they use the same Access Point (AP). Users connected to the same AP use the same Basic Signal Set (BSS) to communicate with the AP. This BSS also allows traffic between users. Depending on the model of AP you are suing, you have the option to block Intra-BSS Traffic (traffic on the BSS between users). This way, users on the same AP will be able to transmit data to the AP, but not to other users on the AP. Wireless security also entails securing traffic between the wireless client and the AP.

This is typically done using encryption standards such as WEP or WPA. However, since this involves the customer changing wireless settings on their computer, this may not always be possible to implement. Not all customers will have permissions on their computer to change settings (especially if it is their company’s computer), or they may not enter the settings correctly. Both can cause connection problems and a bad customer experience.

IMPORTANT: When using WDS bridging (discussed later), Intra-BBS blocking will NOT block traffic from bridged APs. Although the AP will be able to block intra-BBS traffic on itself, it cannot block traffic received from a bridged AP. Therefore, a user on the other end of a WDS bridge may be able to see users on the remote AP, even though Intra-BBS traffic is disabled on both APs. To ensure proper customer security with this feature, it is recommended that bridging NOT be used, and that each AP be connected to the network directly via its own VLAN-enabled Ethernet connection!

Wireless (WDS) Bridging

A Wireless Distribution System (WDS) is a way for APs to exchange information wirelessly, so that each AP does not have to have its own Ethernet cable. In this way, you can bridge APs to each other to increase wireless coverage without additional wiring, while still being able to send information back to your gateway. WDS is an effective way to install wireless coverage in large areas without installing more cables.

Example Bridge Modes:

Static AP Repeater. In this mode, one WLAN interface is configured as an AP interface, and the other is configured as a WDS-based bridge interface. The static AP repeater is suitable for situations in which Ethernet wiring between the AP and the network backbone is impossible or costs highly and the topology of the wireless bridging network is static.

Bridge Repeater. In this mode, both WLAN interfaces are configured as WDS-based static bridge interfaces. A bridge repeater forwards packets between two wireless bridges. It’s possible to use multiple bridge repeaters between two wireless bridges if the distance is very long.

Note: It is important to remember that all communicating devices in a bridge mode, must have the same SSID, otherwise they will not talk to each other.

Wireless installation pointers

Once you’ve completed your site survey, you will know where to install your hot spot for optimal coverage. If you want to keep the Hot Spot near the printer, cash register, in a secure area, etc., you can implement additional Access Points to help cover your area wirelessly.

We present some tips and recommendations on how to extend the effective range of your Whotspot WiFi Gateway, below.

Add a High-gain Antenna to your Whotspot WiFi Gateway

Utilize higher gain antennas. The factory-default antennas that come with an access point usually have low gain (around 2dB). If the access point has removable antennas, then replacing the default antennas with higher gain omni-directional or even directional patch antennas boosts range significantly. Most of these higher gain antennas effectively add 6dB or more to the system, which equates to a four fold increase in signal power. Even though that doesn't exactly multiple the range by four, it does make a big difference in range. For a cost of around ten-fifty dollars each, antenna upgrades are extremely cost-effective.

There are basically two types of high-gain antennas available. An Omni antenna, which broadcasts it's signal in 360 degrees, and a Directional antenna, which as its name implies, broadcasts longer distances in 1 direction. You can visualize how antennas work with a flashlight. Point a flashlight at the ceiling - the circular pattern it makes is light an Omni antenna. If you use a larger flashlight, the size of the circle grows larger. Now, take the same flashlight and point it across the room. The light travels far in the direction you point the flashlight. There is little or no light behind the flashlight, and the pattern of the light is cone-shaped - it starts mall at the source and then grows with distance. This is the way a Directional antenna works.

Add additional omni or directional antennas and you are ready to service your market, regardless the distance. (download Outdoor WiFi Installations [PDF]).

Need more information? Contact Us.

Add WiFi Access Points to your Whotspot WiFi Gateway

A WiFi access point in an inexpensive device that transmits and receives a WiFi signal, and send the information back to the gateway via ethernet cable. WiFi access points are usually wired to the gateway with up to 300 ft. of ethernet cable, or several thousand feet of fiber-optic cable. A typical business quality WiFi access point costs about $125. A nice feature of access points is that you can mix them by using an 802.11g/b/a or other standards to extend the range of your gateway. With a Whotspot gateway, you can add Linksys, D-Link or any other make of WiFi access point to your solution. As an added bonus, you can also extend the range of the Wireless Access Point by adding omni or directional antennas to replace the factory installed ones.

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