方案设计与实施 – 小贴士

A wireless network will frequently go back and forth between the troubleshooting and maintenance-and-optimization phases. For faster deployment, higher performance and greater security of the wireless LAN one should enlist the best practices on each of these phases. It is also very important to consider future requirements such as six month or one year from deployment as the demand for
Wireless interference issues
Wireless networks operate in the unlicensed frequency band between 2.4 and 2.5 GHz in which any device is allowed to operate. Devices such as microwave ovens, cordless phones, Bluetooth devices and even some security devices such as cameras and motion sensors that operate in this band can cause interference. Stats show that as much as 60 percent of wireless LAN problems are interference-based.
A site survey is conducted before deployment to detect sources of interference. Devices that create interference only periodically may not be detected therefore the network planners need the ability to find these types of interferers when they are active and consider them in the design.
Spectrum analyzers with their wireless access points as well as handheld spectrum analysis tools are used to find interference sources. To get rid of interference issue one has a few options:
Remove the interference device.
If you cannot it then put a shield around it so it does not cause interference with your wireless LAN.
If you cannot remove or shield around the interfering device, reconfigure either the wireless system or the interfering device.
Channel Mapping
In order to create effectively a channel map for your enterprise wireless LAN, you will need to know which channels you will use, which channels you are considering using, and which channels your neighbors are using. Channels in the 2.4-GHz band are approximately 20-MHz wide and are spaced approximately 5-MHz apart. In the United States 11 of the 14 channels can be used and only three of those channels (1, 6 and 11) do not overlap with at least one other channel. Adjacent channels can cause rather severe interference therefore cause significant problems for a wireless LAN. If a neighbor is using channel 3 that will create overlapping channels, causing interference between neighboring networks. Both networks’ throughput will be compromised.
Designing the network
Infrastructure-planning tools that are provided with most wireless LAN systems, as well as bundled with site survey tools are very efficient with regards to network design. These tools allow you to simulate radio-frequency (RF) conditions in a number of different environments.
Whether you are designing the wireless network for a warehouse with a lot of metal racks, a hospital with many walled-off rooms and areas, a campus dorm, a hotel or an apartment building software-based simulation tools will allow you to simulate the impact of that physical environment on wireless LAN transmission, and plan accordingly. “What if” analysis is used to determine the optimum access point number and locations to meet current and future needs, by also calculating the effects of additional users and additional applications such as Voice over WiFi.
There are many cables behind a wireless network. An important part of the on wireless-LAN design process is to verify the structured cabling system. Cabling that does not function properly because it is damaged or low quality may not adequately support a mission-critical wireless LAN. So at the very least qualify your cabling plant to Gigabit Ethernet requirements, or be safe and conduct a full certification.
Network verification
We recommend that you conduct a full verification site survey post deployment and before the network is fully populated with users, to ensure the deployed network meets all requirements. You should connect to all access points and service set identifiers to ensure also there are no firewall problems as well as conduct an interference check. It is a good idea to verify channel use and determine if you have too many users on a certain channel.
AirMagnet Survey Pro by Fluke Networks is a great took to use as it can conduct active testing and includes features such as heat maps, which you can use to document verification results. If you have a problem later, you can check the previous maps to see what has changed. Including spectrum analysis in a post-deployment survey allows you to have complementary heat maps and spectral maps for full network documentation.
If your organization needs wireless deployment services please contact Celergy wireless design team to help you deploy a secure and reliable wireless network.

Read more: http://www.articlesbase.com/networks-articles/tips-for-commercial-wireless-lan-deployment-and-optimization-4286570.html#ixzz1NkPhTpQS
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