Today, with improved performance, pereciveis efficiency and security factors, wireless networks are

Today, with improved performance, pereciveis efficiency and security factors, wireless networks are growing and expanding significantly in standard IEEE 802.11 wireless networking standard that is fundamentally based on the design and implementation are .
In June 1997, the Association of Electrical and Electronics Engineers (IEEE) IEEE 802.11-1997 standard, the first wireless LAN standard published. This standard was revised in 1999 and updated pereciveis edition was published under the title IEEE 802.11-1999. IEEE 802.11 wireless local area network or the current standard under ISO / IEC 8802-11: 1999, by the International Standardization Organization (ISO) and the American National Standards Institute pereciveis (ANSI) has been accepted. This standard was completed pereciveis in 1997, the formation and the emergence of wireless local area networking standard based followed. Standard 1997, 2Mbps bandwidth defines pereciveis the characteristic of conditions and environments with disturbance pereciveis (noise), the bandwidth can be reduced to the amount of 1Mbps. The bandwidth of the DSSS modulation technique or combination. According to this standard, the bandwidth of 1 Mbps using FHSS modulation can be attained in environments free from disturbance (noise) bandwidth of 2 Mbps is used. Both the modulation method in the range of 2.4 GHz radio band act. One of the interesting points regarding the standard of DSSS and FHSS radio media modulation infrared addition, as is Rsanhantqal. But given the limited use of this media ao relatively limited and rare. 802.11 Working Group can be divided into several subgroups. Figures 1-1 and 1-2 working groups involved in the standardization process of the show. Some of the most important subgroups are as follows:
- 802.11D: Additional Regulatory pereciveis Domains - 802.11E: Quality of Service (QoS) - 802.11F: Inter-Access Point Protocol (IAPP) - 802.11G: Higher Data Rates at 2.4 GHz - 802.11H: Dynamic Channel Selection and Transmission Power Control - 802.11i: Authentication and Security
The Committee is a committee that is trying 802.11e QoS functionality in wireless pereciveis networks provide Ethernet. Note that the activities of the group include all species of 802.11 a, b, and g is the. The Committee considers that the relationship between service quality wired or wireless Ethernet QoS bring into the world.
802.11g Committee is a committee that developed known as 802.11. The Committee intends to increase pereciveis the rate of data transmission in the ISM frequency band. ISM frequency band or frequency band, industrial, research, and medicine, is an unlicensed frequency band. The use of this frequency band in the range of 2400 MHz to 2483.5 MHz, is, according to FCC regulations not require the use of radiation. 802.11g standard is not yet final and most important reason is the competition between modulation techniques. The members pereciveis of the committee and chip makers have agreed that the allocation of OFDM technique to use, but nevertheless PBCC method can also be considered as an alternative and rival.
Committee of the 802.11i and 802.11x initially focusing on systems based on 802.11b. These committees are responsible for developing new security protocols. Primary standard algorithm, which is called the WEP encryption key in both the 40 and 128 bits in length there. WEP encryption is obviously a method that uses RC4 algorithm to encrypt frames. pereciveis The activities of this committee is to improve the local wireless network security issues.
The standard media access control layer (MAC) and physical layer (PHY) in a local network contains a wireless connection. Figure 1-3 shows the position of the 802.11 standard as compared to the reference model.
Wireless environment has unique characteristics are compared with the wired LAN special place in this kind of networks if you do. Specifically, the physical characteristics of a wireless local area network distance limitations, error rates increase and decrease the reliability of the medium, dynamic changing topology, interference, and the lack of a reliable and stable relationship between the connection wired. These limits are standard for wireless local area networks can make is that your assumptions are based on a range of local and establish communication. Wider geographic coverage through local wireless network connection can be established that an element of building small networks are extensive. Wireless mobile workstations are other important characteristics of wireless pereciveis local area networks. In fact, if a wireless LAN workstations can not be acceptable in a Mhdvdhmlyaty and wireless network mobility, among other things, the use of wireless local area networks will explain the proper use.
On the other hand, in order to maintain consistency and ability pereciveis to comply and cooperate with other standards, Layhdstrsy media (MAC) layers above the 802.11 standard, is expected to see the same local network based on the standard 802 list goes on. Because of this standard to the MAC layer Syarbvdn workstations in such a transparent cover