Introduction to the big family of Wireless Personal Area Networks

Presumably wireless bluetooth is no stranger to everyone. It is one of the technologies of wireless personal area networks. Now, let's take a closer look at the Wireless Personal Area Network family to see which technologies are within its scope. I hope this article will give you a detailed understanding of wireless personal area networks.

A wireless personal Region network uses short-distance and low-power wireless transmission technology to work with the Ad Hoc network architecture (Ad Hoc networks) information Appliances connected to the home environment, personal office desktops or laptops, personal PDAs, and printers can provide medical assistance and leisure entertainment in addition to improving the convenience of living and office environments.

Wireless Personal Area Networks are currently one of the most rapidly developing fields, and new technologies are emerging. For example, 802.11, HiperLAN2, Bluetooth, IrDA, Home RF, and ultra-broadband (UWB) see table 1 for the main technical indicators of the six technologies, including IEEE802.11g.

 

 

1. Six technologies of Wireless Personal Area Networks

Most wireless personal area networks work in the 2.4GHz band (HiperLAN2, UWB, and IrDA do not work in the 2.4GHz band). These technologies have the following advantages:

(1) supports mobile networking. Users can maintain continuous network connections by using mobile phones as flexible mobile computing devices.

(2) It is easy to install without using physical lines. Because the high frequency radio waves used by wireless networks can penetrate walls or glass windows, network devices can be placed freely within the effective range.

(3) multi-layer security protection measures can fully ensure user privacy.

(4) when changing the network structure or layout, you do not need to reset the network.

2. Differences between six Wireless Personal Area Networks

Only specifies the physical layer and MAC layer of the Open System Interconnection Reference Model (OSI/RM). Its MAC layer uses the carrier to listen for multiple accesses/conflicts (CSMA/CA: carrier Sense Multiple Access with Collision Avoidance) protocol, while in the physical layer, 802.11 defines three different physical media: infrared, frequency Hopping Spectrum Expansion (FHSS: Frepuency Hopping Spread Spectrum) and Direct expansion (DSSS: Direct Spectrum Spread Spectrum ). Supports a high data rate, but it mainly supports data communication. For wireless data communication, a wireless Nic must be installed on the data device. The IEEE standard uses the TCP/IP protocol, which is applicable to networks with higher power. The effective working distance is much longer than that of Bluetooth, HomeRF, IrDA, and ultra-broadband (UWB.

The biggest difference between HiperLAN2 and other technologies is that it breaks through the current limits on the spectrum utilization of Wireless LAN. 802.11 (except IEEE802.11a), Bluetooth, and Home RF Technologies all work in the GHz spectrum. The defect is that only 80 MHz frequency bands are available, in addition, Spread Spectrum Communication occupies this frequency band. Considering the limitations of the GHz spectrum, Business License authorities around the world have allocated broadband segments within the 5 GHz spectrum. For example, in the United States, 5.15 ~ 5.35 and 5.725 ~ The available frequencies in the 5.825GHz spectrum are reduced to 300 MHz. In Europe, 5.15 ~ 5.35 and 5.470 ~ The available frequencies within the 5.725GHz spectrum are also widened to 300 MHz. Japan is also considering similar spectrum distribution. These broadband segments are combined with looser management rules to enable high-speed communication for a large number of users. The second is to greatly improve the throughput. The original physical layer throughput is as high as 54 Mbps, and the actual application throughput can be kept at least 20 Mbps. In addition, QoS is supported at high throughput, which provides a new way for real-time applications such as video and voice. Third, its transmission structure can provide connections to various types of network infrastructure (including Ethernet, IP, ATM, and PPP. In addition, each connection has a security authentication and encryption function. Fourth, it also has an automatic frequency management function, which is a new breakthrough in Wireless LAN Management. It makes frequency management easy for HiperLAN2 to promote applications. Based on the above technology, HiperLAN2 combines its high throughput and QoS, and opens up a variety of new application services, such as video signal distribution to the home.