Random access structure for wireless networks

An apparatus for transmitting a random access signal comprising:

• a constant amplitude zero auto correlation (CAZAC) root sequence selector coupled to a CAZAC root sequence generator, wherein the CAZAC root sequence generator generates more than one CAZAC root sequence, and wherein the CAZAC root sequence selector selects a preamble root sequence from one of the CAZAC root sequences;
• a cyclic shifter for modifying the preamble root sequence coupled to the CAZAC root sequence generator;
• a sequence modification selector for selecting a preamble root sequence modification coupled to the cyclic shifter;
• a frequency transformer for transforming a modified prime-length preamble sequence into a prime number of frequency tones coupled to the sequence modifier;
• and
• a tone mapper for mapping a prime number of frequency tones onto a non-prime number of frequency tones coupled to the frequency transformer.

A method of accessing a wireless network comprising:

• transmitting a signal, said signal comprising a constant amplitude zero autocorrelation (CAZAC) sequence autonomously selected from a plurality of CAZAC sequences created by applying cyclic shifts to at least one root CAZAC sequence;
• an integer number of frequency resource blocks are allocated for transmission of said signal;
• and
• duration of said signal is an integer number of data symbols to ease multiplexing random access channel (RACH) and data by reducing orthogonality losses.

An apparatus for transmitting a random access signal, comprising:

• an apparatus for autonomously selecting a signal x(u) and a cyclic shift c among a set of possible signals and cyclic shift values;
• a Zadoff-Chu sequence generator used for generating the signal x(u);
• a cyclic shifter, wherein the cyclic shifter uses the signal x(u) to produce a shifted signal y(u) =x[(u−c) mod U] and wherein c is the selected cyclic shift and U is the length of signal x(u);
• and
• an asynchronous transmitter, wherein the asynchronous transmitter transmits the signal x(u) irrespective of the timing of the target remote receiver.

An apparatus for transmitting a random access signal, comprising:

• an apparatus for autonomously selecting a signal x(u) and a cyclic shift c among a set of possible signals and cyclic shift values;
• a Zadoff-Chu sequence generator used for generating the signal x(u);
• a cyclic shifter;
• wherein the cyclic shifter uses the signal x(u) to produce a shifted signal y(u)=x[(u−c) mod U];
• wherein c is the selected cyclic shift and U is the length of signal x(u), wherein the time-domain signal is x(u);
• an inverse Discrete Fourier Transform (IDFT) transformer coupled to the Zadoff-Chu sequence generator;
• wherein the IDFT transformer produces a time-domain signal;
• a block repeater coupled to the IDFT transformer;
• wherein the block repeater replicates the time domain signal;
• and
• a cyclic prefix inserter coupled to the block repeater.

An apparatus for transmitting a random access signal, comprising:

• an apparatus for autonomously selecting a signal x(u) and a cyclic shift c among a set of possible signals and cyclic shift values;
• a Zadoff-Chu sequence generator used for generating the signal x(u);
• a cyclic shifter, wherein the cyclic shifter uses the signal x(u) to produce a shifted signal y(u)=x[(u−c) mod U], and wherein c is the selected cyclic shift and U is the length of signal x(u);
• an apparatus for producing random access OFDM symbols of duration T1, wherein T1 does not include the cyclic prefix duration;
• and
• an apparatus for producing non-random access OFDM symbols of duration T2, wherein T2 does not include the cyclic prefix duration, and wherein T1 is an integer multiple of T2.

An apparatus for transmitting a random access signal, comprising:

• an apparatus for autonomously selecting a signal x(u) and a cyclic shift c among a set of possible signals and cyclic shift values;
• a Zadoff-Chu sequence generator used for generating the signal x(u);
• a cyclic shifter, wherein the cyclic shifter uses the signal x(u) to produce a shifted signal y(u)=x[(u−c) mod U], and wherein c is the selected cyclic shift and U is the length of signal x(u);
• and
• an apparatus for receiving an indication of c.

An apparatus for transmitting a random access signal, comprising:

• an apparatus for autonomously selecting a signal x(u) and a cyclic shift c among a set of possible signals and cyclic shift values;
• a Zadoff-Chu sequence generator used for generating the signal x(u);
• a cyclic shifter, wherein the cyclic shifter uses the signal x(u) to produce a shifted signal y(u)=x[(u−c) mod U], and wherein c is the selected cyclic shift and U is the length of signal x(u);
• and
• an apparatus for receiving an indication of the Zadoff-Chu sequence.

A method of accessing a wireless network, comprising:

• autonomously selecting a Zadoff-Chu sequence x(u) and a cyclic shift c among a set of possible sequences and cyclic shift values;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u), wherein x(u) is the Zadoff-Chu sequence;
• producing a frequency-domain signal by transforming y(u) with a Discrete Fourier Transform (DFT);
• extending the frequency-domain signal by padding zeros;
• producing a time domain signal by transforming the extended frequency domain signal with an Inverse Discrete Fourier Transform (IDFT);
• repeating the time domain signal;
• inserting a cyclic prefix to the repeated time domain signal;
• and
• broadcasting an indication of the number of repetitions of the time domain signal, wherein the number of repetitions is a cell-specific parameter.

A method of accessing a wireless network, comprising:

• autonomously selecting a Zadoff-Chu sequence x(u) and a cyclic shift c among a set of possible sequences and cyclic shift values;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u);
• and
• frequency multiplexing random access OFDM symbols of duration T1 with non-random access OFDM symbols of duration T2, wherein T1 is an integer multiple of T2.

A method of accessing a wireless network, comprising:

• autonomously selecting a Zadoff-Chu sequence x(u) and a cyclic shift c among a set of possible sequences and cyclic shift values;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u);
• estimating size of a cell in a wireless network;
• producing c using the estimated size of the cell;
• and
• broadcasting an indication of c.

A method of accessing a wireless network, comprising:

• autonomously selecting a Zadoff-Chu sequence and a cyclic shift c among a set of possible sequences and cyclic shift values;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• and
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u), and wherein x(u) is the Zadoff-Chu sequence;
• wherein said Random Access signal is for requesting uplink resource allocation.

A method of accessing a wireless network, comprising:

• producing an element of information at a user equipment;
• autonomously selecting a Zadoff-Chu sequence x(u) and a cyclic shift c among a set of possible sequences and cyclic shift values using the element of information;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• and
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u);
• wherein said Random Access signal is for requesting uplink resource allocation.

A method of accessing a wireless network, comprising:

• autonomously selecting a Zadoff-Chu sequence x(u) and a cyclic shift c among a set of possible sequences and cyclic shift values;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u);
• receiving the random access signal;
• estimating a frequency response of an uplink transmission using the received Random Access signal;
• and
• allocating up-link resources based on said frequency response estimation.

A method of accessing a wireless network, comprising:

• estimating size of a cell in a wireless network;
• producing a primitive cyclic shift value C using the estimated size of the cell;
• broadcasting an indication of C;
• autonomously selecting a Zadoff-Chu sequence x(u) among a set of possible sequences and a cyclic shift c among a set of possible cyclic shift values built as integral multiples of C;
• generating a Random Access signal x(u) using a Zadoff-Chu sequence generator;
• and
• producing a cyclically shifted signal y(u)=x[(u−c) mod U], wherein c is the cyclic shift and U is the length of signal x(u).