Asus WL-160G User Manual download pdf (Page 56)

5. Appendix

56 ASUS 802.11g Access Point

Chapter 5 - Appendix

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.

This algorithm is established by IEEE 802.11b specifications. The bit

redundancy within the chipping sequence enables the receiving wireless mobile

client to recreate the original data pattern, even if bits in the chipping sequence

are corrupted by interference. The ratio of chips per bit is called the spreading

ratio. A high spreading ratio increases the resistance of the signal to interference.

A low spreading ratio increases the bandwidth available to the user. The wireless

device uses a constant chip rate of 11Mchips/s for all data rates, but uses different

modulation schemes to encode more bits per chip at the higher data rates. The

wireless device is capable of an 11 Mbps data transmission rate, but the coverage

area is less than a 1 or 2 Mbps wireless device since coverage area decreases as

bandwidth increases.

Encryption

This provides wireless data transmissions with a level of security.

Extended Service Set (ESS)

A set of one or more interconnected basic service set (BSSs) and integrated

local area networks (LANs) can be configured as an Extended Service Set.

ESSID (Extended Service Set Identifier)

You must have the same ESSID entered into the gateway and each of its wireless

clients. The ESSID is a unique identifier for your wireless network.

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Asus WL-160G User Manual Page 56