| Summary: | 碩士 === 東海大學 === 資訊工程與科學系碩士在職專班 === 93 === Abstract
In 1997, the IEEE adopted IEEE Standard 802.11 as the WLAN standard. This standard defines the Medium Access Control (MAC) and Physical (PHY) layers for a LAN with wireless connectivity. It addresses local area networking where the connected devices communicate over the air to other devices that are close proximity to each other.
The industry group Wireless Ethernet Compatibility Alliance (WECA) certifies its members’ equipment as conforming to the 802.11b standard and enables compliant hardware to be certified as Wi-Fi compatible. This is an attempt to guarantee inter compatibility between hundreds of vendors and thousands of devices.
Wireless Local Area Network (WLAN) grows rapidly in the recent years. Among the various WLAN technologies, the IEEE 802.11b has been used widely. Although IEEE 802.11b is adequate for the wireless connectivity, it has some problems to be resolved.
Through the bilateral contract signature, the internet service providers and wireless internet service providers (ISP/WISP) can deliver end-to-end service-level agreements (SLAs) to guarantee quality of service (QoS) and class of service (CoS). Naturally, the virtual private network (VPN) technology is suitable to provide the low-cost WLAN services over shared public infrastructures to protect user’s data if they requested, VPN also can be deployed in intranet/extranet and internet.
Today, there are many vendors to provide the solutions for overcoming the security and bandwidth management issues -- intrusion detection system (IDS), antivirus, bandwidth management etc. The transmission control protocol (TCP) performance enhancement proxy (PEP) mechanisms have been proposed to improve TCP performance in all-Internet protocol (IP) wireless networks and been deployed widely. Many solutions use the application keyword to do the bandwidth allocation, mail filter and intrusion diction protection (IDP) etc. The application keyword may be retrieved from the application header or data.
However, these security techniques, in part, are mutually conflicted -- a standard IP security protocol with cryptography protection that will make inroad into wireless networks. This paper will propose a solution to extend the multilayer IP security protocol (ML-IPsec) proposed by Yongguang Zhang [1]. Our solution makes IP security protocols compatible with TCP PEP and with applications layer. It allows wireless network operators or service providers, for performance enhancement purposes, to control the base stations' or wireless routers' ability to access the TCP headers. It also can be used by the antivirus and IDP solutions for protection purposes. Through careful design and implementation, we can easily apply our solution to existing IPsec solution.
When WLAN operates in multi-path channel environments, it is influenced by the signal fading (causing from noise interference, signal power unstable, signal skew, etc.). It utilizes the redundancy code technology (e.g. Complementary Code Keying (CCK) [2] [3], Error Detection Code (EDC) and Error Correction Code (ECC) base on hamming code), or utilize deployment, antenna, etc, to overcome the harsh conditions.
We propose a technology, to utilize the FEC function between data link layer and physical link layer for error detection and error correction, to enhance the quality of wireless communication.
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