I. Wireless LAN Networking Requirements
Because wireless LANs need to support high-speed, bursty data services, indoor use also requires addressing issues such as multipath fading and crosstalk between subnets. Specifically, wireless LANs must meet the following technical requirements:
1. Reliability: The packet loss rate of the wireless LAN should be less than 10⁻⁵ and the bit error rate should be less than 10⁻⁸.
2. Compatibility: For indoor wireless LANs, compatibility with existing wired LANs in terms of network operating systems and network software should be maximized.
3. Data rate: In order to meet the needs of local area network traffic, the data transmission rate of wireless local area network should be above 54Mbps.
4. Communication security: Since data is transmitted through the air via wireless media, wireless LANs must take effective measures at different levels to improve communication security and data security.
5. Mobility: Supports full mobile or semi-mobile networks.
6. Energy-saving management: When there is no data transmission or reception, the station is put into sleep mode and activated when data transmission or reception occurs, thereby saving power consumption.
7. Miniaturization and low price: These are the key factors for the widespread adoption of wireless LANs.
8. Electromagnetic environment: The impact of electromagnetic fields on the human body and the surrounding environment should be considered when designing wireless local area networks.
When setting up a wireless local area network (WLAN), many details need to be carefully considered in order to successfully build the WLAN and ensure its high performance.
1. When connecting to a remote LAN via a wireless LAN, the building where the remote LAN is located should be visible to the user as much as possible. If the wireless LAN has to pass through tall buildings or dense trees or other obstacles, the transmission performance of the wireless LAN will be affected, since those obstacles will directly affect the normal transmission of wireless LAN data signals.
2. When the distance between the remote network and the local area network (LAN) is relatively long, the network transmission bandwidth can be appropriately reduced to achieve the purpose of long-distance data transmission. If long-distance wireless transmission is still necessary, consider setting up a wireless LAN relay station in between to allow the internet signal to bypass obstacles. In a wireless LAN, when the network signal is transmitted over short distances, to ensure maximum transmission bandwidth, several wireless bridges should be integrated together, while the antenna height of the wireless LAN remains largely unaffected.
3. Properly setting the antenna height for a wireless LAN is also crucial. If the antenna height of the wireless LAN devices is not set correctly, simply increasing the antenna gain or power amplification will result in very limited wireless transmission performance. Therefore, consider placing the antennas of the wireless node devices on the top floor of the building, and using small antennas to ensure relatively concentrated radio waves. This helps to effectively avoid interference from other wireless LAN signals.
4. Although wireless LAN transmission uses frequency hopping technology, the frequency carrier of the internet signal is difficult to detect. Therefore, secure transmission of the wireless signal is only possible if both parties have the same network ID. To further ensure the security of the wireless LAN, the wireless signal can be encrypted.
II. Network Topology
By combining several devices in a WLAN, a multi-layered computer network that integrates wireless and wired connections can be built. Generally speaking, there are two networking modes for wireless LANs: one is WLAN without a fixed base station, and the other is WLAN with a fixed base station.
WLAN without a fixed base station is a self-contained network, primarily suitable for peer-to-peer networks between computers with wireless network cards. WLAN with a fixed base station is similar to mobile communication; computers with wireless network cards access the network through a base station (wireless access point or wireless router). This type of network is more widely used, typically for extending the coverage of wired LANs or as an access method for broadband wireless internet.
1. WLAN without a fixed base station
WLAN without a fixed base station, also known as a wireless peer-to-peer network, is the simplest type of wireless local area network (WLAN). This type of WLAN has a decentralized topology, where communication between connected devices is equal. However, it is only suitable for wireless connections of a limited number of computers (typically within 5 hosts or devices).
This networking mode does not require fixed facilities; it only requires installing a wireless network card in each computer, making it very suitable for setting up temporary networks.
2. WLAN with fixed base stations
When the number of computer users on the network reaches a certain level, or when a stable wireless network platform needs to be established, an AP-centric networking mode is generally adopted.
The AP-centric networking mode is also the most common networking mode for wireless LANs. In this mode, an AP is required to act as a central station, and all stations' access to the network is controlled by the central station.
