Справочник Пользователя для ASUS wl-300

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. The Space Link Access Point
uses Direct-Sequence Spread Spectrum (DSSS) for radio communication.

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 by the access point 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 access
point 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 access point. Intercepting
and decoding a direct-sequence transmission requires a predefined algorithm
to associate the spreading code used by the transmitting access point 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 access point 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 access point is capable of an 11
Mbps data transmission rate, but the coverage area is less than a 1 or 2
Mbps access point since coverage area decreases as bandwidth increases.