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Wireless Internet

Wireless Internet. Introduction. Introduction. Wireless Internet refers to the extension of the services offered by the Internet to mobile users. Can access information and data irrespective of location. Wireless Internet not same as wired.

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Wireless Internet

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  1. Wireless Internet Introduction

  2. Introduction • Wireless Internet refers to the extension of the services offered by the Internet to mobile users. • Can access information and data irrespective of location. • Wireless Internet not same as wired. • Protocols like TCP and application protocols like TELNET, FTP and SMTP used in wired work poorly in wireless.

  3. Wireless Internet

  4. Major Issues for Wireless Internet • Address Mobility • Inefficiency of transport layer protocols • Inefficiency of application layer protocols

  5. Address Mobility • Internet protocol (IP) designed for wired networks for fixed nodes. • It has hierarchical 32 bit address, mainly divided into subnet and host id. • Used to reduce routing table sizes in core routers, which can use only network id for routing decisions. • This may not work for Wireless as mobile hosts move form one subnet to another. • Packets addressed to mobile host may be delivered to old subnet.

  6. Address Mobility MobileIP is a solution which uses address redirection mechanism.

  7. Inefficiencyof Transport Layer Protocols • Transport layer ensures setting up and maintaining end-to-end connections, end-to-end delivery of data packets, flow control and congestion control. • TCP used in wired (UDP used in some applications) • Wireless medium is inherently unreliable due to time-varying and environment-dependent characteristics.

  8. Inefficiencyof Transport Layer Protocols • TCP invokes congestion control algorithm to control congestion. • If data packet or ACK packet is lost, TCP assumes congestion and reduces congestion window by half. Even in case of link errors or collisions. • Degraded performance, Low throughput in wireless. • Solutions include mobile TCP, snoop TCP, ITCP etc.

  9. Inefficiency of Application Layer protocols • HTTP, TELNET, SMTP and markup languages like HTML optimized for Wired. • Not efficient in wireless, high overhead due to character encoding, redundant info carried in HTTP and new TCP connection for every transaction. • Wireless bandwidth limited and expensive. • Solution is WAP and optimizations over traditional HTTP.

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