Physical structure and sequence design of midamble in OFDMA systems
First Claim
1. A method for providing a midamble channel in an orthogonal frequency division multiple access (OFDMA) system, the method comprising:
- allocating the midamble channel in a subframe having multiple resource blocks by a base station, wherein the resource blocks span over a two-dimensional radio resource region having an array of subcarriers along frequency domain and an array of OFDM symbols along time domain, wherein the midamble channel is allocated to be shared among different transmit antennas; and
transmitting midamble signals via the midamble channel for such that the midamble signals occupy a single OFDM symbol within the subframe, wherein the midamble channel is allocated either in the first OFDM symbol or in the last OFDM symbol of the resource blocks of the subframe, wherein the remaining consecutive OFDM symbols of the same resource blocks are applied with Space Frequency Block Coding (SFBC) for data transmission, andwherein the midamble signals are transmitted for facilitation to calculate a channel quality indicator for a frequency band of a downlink channel.
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Abstract
In wireless OFDMA systems, midamble is used to facilitate downlink (DL) channel estimation. Midamble signals are transmitted by a base station via a midamble channel allocated in a DL subframe. In a novel symbol-based midamble channel allocation scheme, a midamble channel is allocated in the first or the last OFDM symbol of multiple resource blocks of the subframe, while the remaining consecutive OFDM symbols are used for data transmission. The symbol-based midamble channel provides good coexistence between midamble signals and pilot signals without inducing additional limitation or complexity. Under a novel midamble channel and sequence arrangement, both code sequence and either time-domain or frequency-domain location degrees-of-freedom are considered such that the required number of midamble sequences is substantially smaller than the number of strong interferences. In addition, different midamble sequences are systematically generated based on a base sequence such that the receiving mobile station does not need to memorize all the different code sequences.
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Citations
18 Claims
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1. A method for providing a midamble channel in an orthogonal frequency division multiple access (OFDMA) system, the method comprising:
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allocating the midamble channel in a subframe having multiple resource blocks by a base station, wherein the resource blocks span over a two-dimensional radio resource region having an array of subcarriers along frequency domain and an array of OFDM symbols along time domain, wherein the midamble channel is allocated to be shared among different transmit antennas; and transmitting midamble signals via the midamble channel for such that the midamble signals occupy a single OFDM symbol within the subframe, wherein the midamble channel is allocated either in the first OFDM symbol or in the last OFDM symbol of the resource blocks of the subframe, wherein the remaining consecutive OFDM symbols of the same resource blocks are applied with Space Frequency Block Coding (SFBC) for data transmission, and wherein the midamble signals are transmitted for facilitation to calculate a channel quality indicator for a frequency band of a downlink channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A base station in an OFDMA system, the base station comprising:
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a midamble channel allocation module for allocating a midamble channel in a subframe having multiple resource blocks that span over a two-dimensional radio resource region having an array of subcarriers along frequency domain and an array of OFDM symbols along time domain, wherein the midamble channel is allocated to be shared among different transmit antennas; and transmitting midamble signals via the midamble channel to, wherein the midamble channel is allocated either in the first OFDM symbol or in the last OFDM symbol of the resource blocks of the subframe, and wherein the remaining consecutive OFDM symbols of the same resource blocks are applied with Space Frequency Block Coding (SFBC) used for data transmission, and wherein the midamble signals are transmitted for facilitation to calculate a channel quality indicator for a frequency band of a downlink channel. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification