Research on the process of WiFi communication--(3) conceptual subdivision of transmission process

Third, the transmission Process concept subdivision

(a), encryption algorithm analysis

1. WEP

1) wep:wired equivalent Privacy

2) presented with the 802.11 standard

3) RC4 Encryption algorithm

4) 2 Types of strength: 40bits and 104bits

5) initialization vector (IV) = Bits

6) Wep2:128bit

2. WPA

1) WPA: ieee802.11i standard for draft

2) 128bits RC encryption algorithm

3) Use one password per data frame

4) TKIP Dynamic Password Management protocol

3, WPA2

1) WPA2: the formal ieee802.11i standard

2) using AES encryption algorithm

3) Support 128bits,192bits,256bits

4) CCMP Password Management protocol

5) Support cache key and pre-authentication

Figure 12 Introduction to decryption algorithms

(b), WiFi usage frequency

1, 2.4GHz Band Division

1) The operating frequency range is 2400-2483.5 MHz, which belongs to the ISM band without application;

2) Frequency interference is unavoidable due to the use of ISM band;

3) 83.5MHz bandwidth, divided into 13 channels, each channel bandwidth is 22MHz;

4) overlap between adjacent channels, try not to use simultaneously, causing interference;

5) in the same cover the rest can only be used at the same time 3 non-overlapping channels;

Figure 2.4GHz Band

2, 5.8GHz Band Division

1) using the operating frequency range of 5725-5850 MHz;

2) The available bandwidth is 125MHz, divided into 5 channels, each channel bandwidth is 20MHz;

3) The adjacent channels do not overlap;

Figure 5.8GHz Band

Appendix

(a), WLAN standard family

IEEE 802.11	Specification for physical layer and media access layer
IEEE 802.11j	The equivalent of the IEEE 802.11h specification used in Japan
IEEE 802.11i	Security enhancement Protocol for wireless local media access control layer
IEEE 802.11h	Additional definition of physical layer requirements (e.g. channelized, FH mode, etc.)
IEEE 802.11g	2.4GHz Band high-speed physical layer expansion
IEEE 802.11f	Support for IEEE 802.11 Access Point Interop Protocol (IAPP)
IEEE 802.11e	MAC Layer Enhancements-Service Quality assurance (QoS)
IEEE 802.11d	Special requirements for physical layers
IEEE 802.11b	Physical layer and media Access layer specification--2.4ghz band high-speed physical layer expansion
IEEE 802.11a	Specification for physical layer and media Access layer specification for--5.8ghz band high-speed physical layer
IEEE 802.11k	RF Resource Management
IEEE 802.11u	Interoperability with other networks
IEEE 802.11v	Wireless network Management
IEEE 802.11t	Wireless network performance prediction
IEEE 802.11s	Mesh Mesh Mesh
IEEE 802.11R	Fast Roaming
IEEE 802.11q	Support Mechanisms for VLANs
IEEE 802.11p	Wireless communication in vehicle conditions
IEEE 802.11o	VoWLAN
IEEE 802.11n	Specification for high-speed physical layer and media access layer
IEEE 802.11m	Maintenance, correction and improvement of the IEEE 802.11 specification system

(b), technical terms

AP Wireless access point ( responsible for simple wireless signal transceiver, equivalent to the wireless hub. )

The ISM band does not need to apply for frequency-consuming bands;

OFDM Orthogonal Frequency Division Multiplexing

CSMA/CA Carrier Listen multiple access/collision avoidance (MAC layer access control)

DSSS Direct sequence spread spectrum modulation technology

CCK Complementary key control technology

PBCC packet binary convolution technology

DBPSK Differential Two phase phase shift keying

DQPSK Differential quadrature phase shift keying

MCM Multi-carrier modulation

IFFT reverse Fast Fourier transform

FFT Fast Fourier transform

SSID Service Set ID Services sets identification code

WAI Wireless LAN Authentication

WPI Security Infrastructure

EVM Vector Error

RSSI Receive signal sensitivity

QoS Quality of service

WMM wi-fi multimedia
WPA Wi-Fi Protected Access
WPA2 Wi-Fi Protected Access 2

(iii), signal penetration loss estimation

Figure 1 signal penetration loss estimation

Research on the process of WiFi communication--(3) conceptual subdivision of transmission process