Mitsubishi Electronics A111 user manual Dhcp Dynamic Host Configuration Protocol

Chapter 5 Glossary

Chapter 5 - Glossary

DHCP (Dynamic Host Configuration Protocol)

This protocol allows a computer (or many computers on your network) to be automatically assigned a single IP address from a DHCP server.

DNS Server Address (Domain Name System)

DNS allows Internet host computers to have a domain name and one or more IP addresses. A DNS server keeps a database of host computers and their respective domain names and IP addresses, so that when a user enters a domain name into the Internet browser, the user is sent to the proper IP address. The DNS server address used by the computers on your home network is the location of the DNS server your ISP has assigned.

DSL Modem (Digital Subscriber Line)

A DSL modem uses your existing phone lines to transmit data at high speeds.

Direct-Sequence Spread Spectrum (for 802.11b)

Spread spectrum (broadband) uses a narrowband signal to spread the transmission over a segment of the radio frequency band or spectrum. Direct- sequence is a spread spectrum technique where the transmitted signal is spread over a particular frequency range.

Direct-sequence systems communicate by continuously transmitting a redundant pattern of bits called a chipping sequence. Each bit of transmitted data is mapped into chips and rearranged into a pseudorandom spreading code to form the chipping sequence. The chipping sequence is combined with a transmitted data stream to produce the output signal.

Wireless mobile clients receiving a direct-sequence transmission use the spreading code to map the chips within the chipping sequence back into bits to recreate the original data transmitted by the wireless device. Intercepting and decoding a direct-sequence transmission requires a predefined algorithm to associate the spreading code used by the transmitting wireless device to the receiving wireless mobile client.

ThisalgorithmisestablishedbyIEEE802.11bspecifications.Thebitredundancywithin thechippingsequenceenablesthereceivingwirelessmobileclienttorecreatetheoriginal data pattern, even if bits in the chipping sequence are corrupted by interference. The ratio of chips per bit is called the spreading ratio.Ahigh spreading ratio increases the resistance of the signal to interference.Alow spreading ratio increases the bandwidth availabletotheuser.Thewirelessdeviceusesaconstantchiprateof11Mchips/sforall data rates, but uses different modulation schemes to encode more bits per chip at the higherdatarates.Thewirelessdeviceiscapableofan11Mbpsdatatransmissionrate, but the coverage area is less than a 1 or 2 Mbps wireless device since coverage area decreasesasbandwidthincreases.

38 A111 Wireless Card Adaptor