Reference Signal Sequences and Multi-User Reference Signal Sequence Allocation
AssigneeTexas Instruments Incorporated
InventorsTarik Muharemovic, Eko Onggosanusi, Aris Papasakellariou
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Abstract
Embodiments of the invention provide method for allocating CAZAC pilot (reference signal) sequences in multiple access OFDMA systems, or alternatively, in multiple access DFT-spread OFDM(A) systems (or SC-FDMA). Reference signal transmissions from different mobiles can either be distinguished by use of disjoint sub-carriers (frequency division orthogonality), or alternatively by use of distinct cyclic shifts of one base CAZAC sequence. In a wireless cellular network, neighboring cells should utilize different CAZAC sequences, in order to mitigate out-of-cell interference.
Claims48
An apparatus for forming a signal in single-carrier frequency division multiple access (SC-FDMA) transmission system, said apparatus comprising:
- Constant Amplitude Zero Auto-Correlation (CAZAC) sequencer creating at least one CAZAC sequence;
- and
- transmitter for transmitting said at least one CAZAC sequence in accordance with the single-carrier frequency division multiple access (SC-FDMA) transmission method.
An apparatus for forming a signal in single-carrier frequency division multiple access (SC-FDMA) transmission system, said apparatus comprising:
- Constant Amplitude Zero Auto-Correlation (CAZAC) sequencer creating at least a first CAZAC sequence;
- receiver for receiving at least a second CAZAC sequence;
- and
- processor configured to process said at least second CAZAC sequence with said at least first CAZAC sequence.
An apparatus in a communication link, said comprising:
- Constant Amplitude Zero Auto-Correlation (CAZAC) sequencer creating at least one CAZAC sequence;
- cyclic shifter for forming a plurality M mutually orthogonal sequences through M−1 cyclic shifts of said at least one CAZAC sequence;
- and
- allocator for allocating to at least one user equipment, from a plurality of user equipments, at least one shift of said M−1 cyclic shifts of said at least one CAZAC sequence.
An apparatus comprising:
- Constant Amplitude Zero Auto-Correlation (CAZAC) sequencer creating at least one CAZAC sequence;
- cyclic shifter for forming at least one of M mutually orthogonal CAZAC sequences;
- and
- selector for selecting at least one of said at least one of M mutually CAZAC orthogonal sequences for transmission with a single-carrier frequency division multiple access (SC-FDMA) communication method.
A method for allocating at least one CAZAC sequence to a plurality of user equipments in a communication system, said method comprising:
- selecting a CAZAC sequence of length L;
- forming M mutually orthogonal CAZAC sequences through M−1 cyclic shifts of length Q of said CAZAC sequence of length L;
- and
- allocating to at least one user equipment, from said plurality of user equipments, at least one shift of said M−1 cyclic shifts of said CAZAC sequence of length L.
A method for coordinating the assignment of a CAZAC sequence in each Node B in a set of Node Bs, said method comprising:
- selecting a CAZAC sequence in at least one Node B in said set of Node Bs;
- and
- signaling said selected CAZAC sequence by said at least one Node B in said set of Node Bs to remaining Node Bs in said set of Node Bs.
A method for coordinating the assignment of a CAZAC sequence in each Node B is a set of Node Bs, said method comprising:
- selecting a CAZAC sequence in at least one Node B in said set of Node Bs in response to signaling from a central Node for said set of Node Bs.
A method for coordinating in each Node B in a set of Node Bs the allocation of CAZAC sequences to a plurality of user equipments in said each Node B in a set of Node Bs, said method comprising:
- selecting a set of mutually orthogonal CAZAC sequences;
- and
- assigning each CAZAC sequence from said set of mutually orthogonal CAZAC sequences to each said Node B in a set of Node Bs.
A method for allocating a CAZAC sequence to a plurality of user equipments in a communication system, for transmission over at least two consecutive time periods, said method comprising:
- selecting a CAZAC sequence of length L;
- allocating to a first user equipment from said plurality of user equipments, said selected CAZAC sequence for transmission in said at least two consecutive time periods;
- allocating to a second user equipment, from said plurality of user equipments, said selected CAZAC sequence for transmission in a first of said at least two consecutive time periods;
- and
- allocating to said second user equipment the algebraic opposite (negative) of said selected CAZAC sequence for transmission in a second of said at least two consecutive time periods.
A method for allocating at least two CAZAC sequences to a plurality of user equipments in a communication system, for transmission over at least two consecutive time periods, said method comprising:
- selecting a CAZAC sequence of length L;
- forming at least two mutually orthogonal CAZAC sequences by making cyclic shifts of length Q for said selected CAZAC sequence of length L;
- allocating to a first user equipment, from said plurality of user equipments, a first of said at least two mutually orthogonal CAZAC sequences for transmission in said at least two consecutive time periods;
- and
- allocating to a second user equipment, from said plurality of user equipments, a second of said at least two mutually orthogonal CAZAC sequences for transmission in a first of said at least two consecutive time periods and for transmission of the algebraic opposite (negative) of said second of said at least two mutually orthogonal CAZAC sequences in a second of said at least two consecutive transmission periods.
A method for transmitting during at least two consecutive transmission time periods a CAZAC sequence at a user equipment in a communication system, said method comprising:
- transmitting said CAZAC sequence in a first of said at least two consecutive transmission time periods;
- transmitting the algebraic opposite (negative) of said CAZAC sequence in a second of said at least two consecutive transmission time periods.
A method for multiplexing two CAZAC sequences allocated to a first and second user equipments in a communication system, said communication system having a transmission bandwidth, said method comprising:
- selecting a first CAZAC sequence of length L1;
- allocating said first CAZAC sequence to said first user equipment for transmission into a first portion of said bandwidth selecting a second CAZAC sequence of length L2;
- and
- allocating said second CAZAC sequence to said second user equipment for transmission into a second portion of said bandwidth;
- wherein said transmission of said first CAZAC sequence and said transmission of said second CAZAC sequence do not occupy any common sub-carriers in any of said portions of said transmission bandwidth.
A method for creating a reference signal for communication from a user equipment to a Node B, wherein said reference signal is constructed from a CAZAC sequence, said method comprising;
- constructing a CAZAC sequence;
- mapping said CAZAC sequence to used sub-carriers;
- inserting zeros for the unused sub-carriers;
- and
- performing the IFFT operation on all sub-carriers.
A frame structure, said structure comprising;
- a plurality of long blocks containing data;
- and
- a plurality of short blocks containing reference signals constructed from at least one CAZAC sequence.
A method for multiplexing CAZAC reference signals from at least two users equipments (UEs), said method comprising;
- determining at least one used sub-carrier mapping for each of said at least two UEs;
- signaling said at least one used sub-carrier mapping to each of said at least two UEs;
- and
- receiving the multiplexed transmissions from each of said at least two UEs.
A method for multiplexing CAZAC reference signals from at least two user equipments (UEs), said method comprising:
- determining at least one cyclic shift for each of said at least two UEs;
- signaling said at least one cyclic shift to each of said at least two UEs;
- and
- receiving the multiplexed transmissions from each of said at least two UEs.
A method for combined hybrid multiplexing of CAZAC reference signals from at least two user equipments (UEs), said method comprising:
- determining at least one used sub-carrier mapping for each of said at least two UEs;
- determining at least one cyclic shift for each of said at least two UEs;
- signaling the used sub-carrier mapping to each of said at least two UEs;
- signaling said at least one cyclic shift to each of said at least two UEs;
- and
- receiving the multiplexed transmissions from each of said at least two UEs.
Dependencies are inferred from the claim text.