Differentially encoded pilot word system and method for wireless transmissions of digital data

Claim 3

The method according to claim 1, wherein step (d) comprises the step of monitoring the difference between received channel-impaired symbols over a plurality of pilot periods to detect a periodic occurrence of the predetermined pilot difference, the periodic occurrence of the predetermined pilot difference indicating the periodic position of the pilot word.

Claim 4

The method according to claim 1, wherein the pilot word periodically inserted in step (a) consists of two pilot symbols that are separated by a predetermined phase difference.

Claim 5

The method according to claim 1, wherein the pilot word consists of two pilot symbols that are separated by a predetermined phase difference and a predetermined amplitude difference.

Claim 6

The method according to claim 1, wherein the pilot word consists of first, second and third pilot symbols, and wherein said first and second pilot symbols are separated by a first predetermined difference and said second and third pilot symbols are separated by a second predetermined difference.

Claim 7

The method according to claim 1, further comprising the step of: (g) using an estimate generated in step (f) to compensate the amplitude and phase of channel-impaired data symbol.

Claim 8

A transmitter for transmitting data over a wireless channel, comprising: a constellation mapper that receives a data stream and generates a data symbol stream by transforming binary values of said data stream into corresponding symbols; a pilot word generator that generates differentially encoded pilot words, each differentially encoded pilot word comprising at least two pilot symbols; a pilot word inserter that periodically inserts said pilot symbols of said pilot words into said data symbol stream to produce a composite symbol stream; a filter for filtering said composite symbol stream; and a radio frequency up-converter that generates a radio frequency representation of said composite symbol stream for transmission over the wireless channel.

Claim 9

A transmitter for transmitting data over a wireless channel, comprising: a constellation mapper that receives a data stream and generates a data symbol stream by transforming binary values of said data stream into corresponding symbols; a pilot word generator that generates differentially encoded pilot words, each differentially encoded pilot word comprising at least two pilot symbols; a pilot word inserter that periodically inserts said pilot symbols of said pilot words into said data symbol stream to produce a composite symbol stream; a filter for filtering said composite symbol stream; and a radio frequency up-converter that generates a radio frequency representation of said composite symbol stream for transmission over the wireless channel.

Claim 10

The transmitter according to claim 7, wherein said pilot word generator generates differentially encoded pilot words by generating two pilot symbols that are a predetermined, fixed difference apart.

Claim 11

A transmitter for transmitting data over a wireless channel, comprising: a constellation mapper that receives a data stream and generates a symbol stream by transforming binary values of said data stream into corresponding symbols; an inserter that periodically inserts predetermined binary values into said data stream to cause said constellation mapper to generate pilot symbols; a pilot word generator that generates the predetermined binary values that are inserted by the inserter, the predetermined binary values generated so as to produce periodic, differentially encoded pilot words in said symbol stream; a filter for filtering said symbol stream; and a radio frequency up-converter that generates a radio frequency representation of said symbol stream for transmission over the wireless channel.

Claim 12

A transmitter for transmitting data over a wireless channel, comprising: a constellation mapper that receives a data stream and generates a symbol stream by transforming binary values of said data stream into corresponding symbols; an inserter that periodically inserts predetermined binary values into said data stream to cause said constellation mapper to generate pilot symbols; a pilot word generator that generates the predetermined binary values that are inserted by the inserter, the predetermined binary values generated so as to produce periodic, differentially encoded pilot words in said symbol stream; a filter for filtering said symbol stream; and a radio frequency up-converter that generates a radio frequency representation of said symbol stream for transmission over the wireless channel.

Claim 13

The transmitter according to claim 9, wherein each differentially encoded pilot word consists of two pilot symbols that are separated by a fixed difference.

Claim 14

A receiver for receiving a stream of symbols transmitted over a wireless channel, the stream of symbols comprising data symbols and comprising pilot symbols that are arranged as differentially encoded pilot words, each differentially encoded pilot word comprising at least two pilot symbols that are separated by a fixed difference, the differentially encoded pilot words being spaced apart in the symbol stream by a pilot period, the receiver comprising: an antenna that receives the stream of symbols as a radio frequency signal; a down-converter that transforms the radio-frequency signal into a baseband signal; a filter that bandlimits the baseband signal; a sampler that samples the baseband signal to generate a stream of symbol values; a detector that detects the periodic position of the differentially encoded pilot words within the stream of symbols by monitoring differences between symbol values of said stream of symbol values over multiple pilot periods; a pilot symbol extractor that extracts the differentially encoded pilot words from the stream of symbols by extracting pilot symbol values from said stream of symbol values; a channel estimator that compares pilot symbol values extracted by said pilot symbol extractor with transmitted pilot symbol values to generate channel estimates; a channel compensator that compensates data symbols in the stream of symbols by using said channel estimates to adjust data symbol values in said stream of symbol values, the channel compensator thereby producing a stream of compensated data symbols; and a demodulator that converts said stream of compensated data symbols to a stream of digital data by converting compensated data symbols into corresponding binary data values.

Claim 15

A receiver for receiving a stream of symbols transmitted over a wireless channel, the stream of symbols comprising data symbols and comprising pilot symbols that are arranged as differentially encoded pilot words, each differentially encoded pilot word comprising at least two pilot symbols that are separated by a fixed difference, the differentially encoded pilot words being spaced apart in the symbol stream by a pilot period, the receiver comprising: an antenna that receives the stream of symbols as a radio frequency signal; a down-converter that transforms the radio-frequency signal into a baseband signal; a filter that bandlimits the baseband signal; a sampler that samples the baseband signal to generate a stream of symbol values; a detector that detects the periodic position of the differentially encoded pilot words within the stream of symbols by monitoring differences between symbol values of said stream of symbol values over multiple pilot periods; a pilot symbol extractor that extracts the differentially encoded pilot words from the stream of symbols by extracting pilot symbol values from said stream of symbol values; a channel estimator that compares pilot symbol values extracted by said pilot symbol extractor with transmitted pilot symbol values to generate channel estimates; a channel compensator that compensates data symbols in the stream of symbols by using said channel estimates to adjust data symbol values in said stream of symbol values, the channel compensator thereby producing a stream of compensated data symbols; and a demodulator that converts said stream of compensated data symbols to a stream of digital data by converting compensated data symbols into corresponding binary data values.

Claim 16

The receiver according to claim 11, wherein said detector generates cumulative summation value over multiple pilot periods with one cumulative summation value generated for each possible periodic position within the stream of symbols where the differentially encoded pilot words may be located, each cumulative summation value representing a cumulative symbol difference for two symbol positions.

Claim 17

A transmitter that transmits a sequential stream of data, the sequential stream of data comprising: a stream of data symbols; and a series of pilot words where each word comprises two differentially encoded symbols spaced at substantially equal time intervals within said stream of data symbols, at least some of said pilot words being identical to each other.

Claim 18

A transmitter that transmits a sequential stream of data, the sequential stream of data comprising: a stream of data symbols; and a series of pilot words where each word comprises two differentially encoded symbols spaced at substantially equal time intervals within said stream of data symbols, at least some of said pilot words being identical to each other.

Claim 19

The transmitter according to claim 13, wherein all pilot words are identical.

Claim 20

The transmitter according to claim 13, wherein every other pilot word is identical.

Claim 21

The transmitter according to claim 13, wherein the differential encoding comprises a fixed difference between the pilot word symbols.

Claim 22

The transmitter according to claim 16, wherein the fixed difference is a difference in amplitude.

Claim 23

The transmitter according to claim 16, wherein the fixed difference is a difference in phase.

Claim 24

The transmitter according to claim 13, in combination with a receiver that is designed to receive the sequential stream of data.

Claim 25

The transmitter according to claim 13, wherein said transmitter transmits the sequential stream of data as a radio frequency signal on a wireless channel.

Claim 26

A sequential stream of data, the sequential stream of data comprising: a stream of data symbols; and a series of pilot words that comprise two differentially encoded symbols spaced at substantially equal time intervals within said stream of data symbols, at least some of said pilot words being identical to each other.

Claim 27

A sequential stream of data, the sequential stream of data comprising: a stream of data symbols; and a series of pilot words that comprise two differentially encoded symbols spaced at substantially equal time intervals within said stream of data symbols, at least some of said pilot words being identical to each other.

Claim 28

The sequential stream of data according to claim 21, wherein all of said pilot words are identical.

Claim 29

The sequential stream of data according to claim 21, wherein every other pilot word is identical.

Claim 30

The sequential stream of data according to claim 21, wherein said two differentially encoded symbols differ from one another by a fixed phase.

Claim 31

The sequential stream of data according to claim 21, in combination with a receiver configured to receive the sequential stream of data.