8 limited power mobile nodes are battery operated and

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Unformatted text preview: used in mobile wireless systems includes smart phones, personal digital assistants (PDAs), and pagers with Internet access. Note that mobile users do not necessarily need to use wireless interfaces and wireless interfaces do not necessarily support mobility. A mobile user can simply connect to fixed networks using wired interfaces as he/she moves. Likewise, a fixed-location user might use a wireless interface (via a LAN) while sitting in an office. Therefore, mobile and wireless computing systems are not the same even though there is considerable overlap. Issues in Wireless Computing Systems Wireless computing systems communicate by modulating radio waves or pulsing infrared light. Wireless communication is linked to the wired network infrastructure by stationary transceivers. The area covered by an individual transceiver's signal is known as a cell. Cell sizes vary widely. For instance, an infrared transceiver can cover a small meeting room, a cellular phone transceiver has a range of a few miles, and a satellite beam can cover an area more than 400 miles in diameter. The successful use of wireless computing systems faces several challenges. The important ones among them are as follows: 1. Lower bandwidths. Wireless communication is characterized by lower bandwidths. That is, the channel capacity typically available in wireless systems is much lower than what is available in wired networks due to the limited spectrum available, power restrictions, and noise levels. 2. Variable bandwidths. In case of mobile wireless systems, the limited bandwidth that is available is also variable depending on location. Channel reuse must, therefore, be an integral part of the system in order to provide service to as many potential subscribers as possible. 3. Higher error rates. Noise and interference have more impact on wireless computing systems than for wired computing systems. This, in turn, increases communication latency resulting from retransmissions, retransmission time-out delays, and error-correction protocol processing. 4. Increased security concerns. Security is a greater concern in...
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