Product details

• Catalog Description:
• RB540 Dummy Module, Half Height Double
  
• Long Description:
• RB540 Dummy Module, Half Height Double Width
• Product Type:

• Control_System_Accessory

• Product Net Depth / Length:
• 0 mm
  
• Product Net Height:
• 0 mm
  
• Product Net Width:
• 0 mm
  
• Product Net Weight:
• 0.06 kg

IEEE 802.11b wireless networking standard

1. Physical layer of wireless LAN

The difference between wireless LAN and traditional wired LAN is reflected in the physical layer that wireless LAN generally uses radio as the transmission medium, rather than traditional cables. For IEEE 802.11b wireless Lans, there are three optional physical layers: Frequency hopping spread spectrum (FHSS) physical layer, Direct sequence spread spectrum (DSSS) physical layer, and infrared (IR) physical layer. The choice of physical layer depends on the requirements of the actual application. Frequency hopping spread spectrum (FSS) and direct sequence spread spectrum (DSS) are two common spread spectrum technologies in communication technology, which are used to improve the utilization rate of wireless channel and the security of data communication. At present, the physical layer media of most IEEE 802.11B-based wireless LAN products operate in the 2.4000~2.4835GHz radio frequency band (ISM band), using direct sequence spread spectrum technology to provide data transmission rates of up to 11Mbps.

2. MAC protocol of wireless LAN

In principle, there is no essential difference between the MAC protocol of wireless LAN and that of wired LAN. However, due to the inherent characteristics of wireless transmission media and the influence of mobility, the MAC protocol of wireless LAN can not follow the original LAN protocol. For example, the MAC layer of IEEE 802.3 uses CSMA/CD to enable different sites to share the same physical channel. An important prerequisite for the implementation of CSMA/CD is that each site can easily implement the conflict detection function. In the case of wired local area networks (such as Ethernet), conflict detection can be easily implemented based on changes in the DC component of the detection cable line. However, when using wireless transmission media, it is difficult to implement conflict detection for the following reasons.

 ABB series of products

[Disclaimer] :

Guizhou Yuanmiao Automation Equipment Co., LTD. We sell new products and discontinued products, independent channels to purchase such special products. Guizhou Yuanmiao Automation Equipment Co., Ltd. is not an authorized distributor, distributor or representative of the featured products on this website. All product names/product images, trademarks, brands and logos used on this website are the property of their respective owners. Descriptions, descriptions or sales of products bearing these names, images, trademarks, brands and logos are for identification purposes only and do not imply any association or authorization with any rights holder.