Wireless internet access system and method
View Patent ↗A wireless Internet access system and method supports the transmission and reception of multiple types of traffic between mobile subscriber units and existing networks. A frame structure is used that can support the transmission of multiple types of traffic and adapt to changes in the traffic types needed and the amount of data for a particular traffic type. In addition, data transmission is performed using orthogonal frequency division multiplexing and differential phase shift keying to avoid intersymbol interference. Receiving units in the mobile subscriber units and existing networks include antenna arrays to provide a multipath transmission.
1. A method for decoding symbols modulated onto a plurality of subcarriers, each symbol corresponding to one or more data bits where each combination of bits represents a unique phase, comprising the steps of:
receiving, at a plurality of antennas, a waveform formed from the superposition of a plurality of modulated subcarriers, each modulated subcarrier having a different frequency and formed by modulating one of a plurality of serial symbols onto a corresponding one of a plurality of subcarriers based on the difference in phase between each pair of adjacent symbols;
extracting the response of each antenna to each of the individual subcarriers;
forming a vector for each subcarrier having a plurality of elements equal to the number of antennas, each element of a vector of a particular subcarrier representing the extracted response of one of the plurality of antennas to the particular subcarrier;
combining mathematically the vectors corresponding to each pair of adjacent subcarriers to calculate the phase difference between each pair of adjacent subcarriers; and
determining the value of each symbol based on the phase differences resulting from the mathematical combination of each pair of adjacent vectors.
2. A system for decoding symbols modulated onto a plurality of subcarriers, each symbol corresponding to one or more data bits where each combination of bits represents a unique phase, said system comprising:
a plurality of antennas;
means for receiving at said antennas a waveform formed from the superposition of a plurality of modulated subcarriers, each modulated subcarrier having a different frequency and formed by modulating one of a plurality of serial symbols onto a corresponding one of a plurality of subcarriers based on the difference in phase between each pair of adjacent symbols;
means for extracting the response of each of said antennas to each of the individual subcarriers;
means for forming a vector for each subcarrier having a plurality of elements equal to the number of antennas, each element of a vector of a particular subcarrier representing the extracted response of one of said plurality of antennas to the particular subcarrier;
means for mathematically combining the vectors corresponding to each pair of adjacent subcarriers to calculate the phase difference between each pair of adjacent subcarriers; and
means for determining the value of each symbol based on the phase differences resulting from the mathematical combination of each pair of adjacent vectors.