摘要:
A channel estimation device estimates channel by a previous signal, comprising an F evaluation module, a digitalization module, and a transferring module. The evaluation module processes a initial channel estimation according to at least one pilot signal of the previous signal. The digitalization module digitalizes a data carrier to a digital data signal according to the initial channel estimation. The transferring module transfers the digital data signal to at least one of specific references. The evaluation module receives a new data signal and modulates the new data signal according to the specific references.
摘要:
A communication apparatus, a method, and a tangible machine-readable medium thereof for processing ranging interference of an orthogonal frequency division multiplexing (OFDM) signal. The communication apparatus comprises a receiving unit, a processing unit, and a mask generating unit. The receiving unit receives the OFDM signal having a plurality of OFDM symbols. The processing unit estimates a delay value and an energy value of at least one ranging code according to the OFDM symbols. The mask generating unit generates a mask function according to the delay value and the energy value. Finally, the processing unit synthesizes the ranging interference in the OFDM signal and removes it according to the mask function.
摘要:
A preamble sequence detection and integral carrier frequency offset estimation method for OFDM/OFDMA wireless communication systems by formulating integral carrier frequency offset estimation and preamble sequence detection as a signal detection problem in multi-channel interference, obtaining the theoretically optimal solution, and deriving simplified, approximately optimal solutions, in which frequency-domain filtering is employed to calculate the required correlation values, which can drastically reduce the high computational complexity of the original theoretically optimal solution but result in little impact on precision. In addition, several further simplified algorithms are provided, some of which can even eliminate the use of multipliers. The using of frequency-domain filtering has high extensibility in application to related signal sequence detection problems.
摘要:
A communication apparatus, a method, and a tangible machine-readable medium thereof for processing ranging interference of an orthogonal frequency division multiplexing (OFDM) signal. The communication apparatus comprises a receiving unit, a processing unit, and a mask generating unit. The receiving unit receives the OFDM signal having a plurality of OFDM symbols. The processing unit estimates a delay value and an energy value of at least one ranging code according to the OFDM symbols. The mask generating unit generates a mask function according to the delay value and the energy value. Finally, the processing unit synthesizes the ranging interference in the OFDM signal and removes it according to the mask function.
摘要:
This invention discloses a method for OFDM and OFDMA channel estimation via phase-rotated polynomial interpolation and extrapolation (inter/extra-polation). For complexity reason, polynomial inter/extra-polation is an often considered method for channel estimation in orthogonal frequency-division multiplexing (OFDM) and orthogonal frequency-division multiple access (OFDMA) systems, in which the simplest choice is linear inter/extra-polation. But the performance of this method depends on the accuracy of symbol timing estimation as well as the channel delay spread. The invention mitigates the problem by adding a linear phase factor to polynomial inter/extra-polation, which corresponds to adding a delay (also called delay shift) in the time domain.
摘要:
The present invention relates to a channel estimation technique for multi-carrier system which uses pilot signal to first obtain pilot subcarrier channel responses, then estimate the mean delay and the root-mean-square delay spread of the channel, and then uses interpolation to obtain the channel responses of arbitrary subcarriers. The present invention is able to perform channel estimation and to accurately estimate various channel delay parameters (such as the initial delay, the mean delay, and the root-mean-square delay spread) with very low quantity of pilot signal and with low computational complexity. In addition, the present invention has broad applicability, as it does not require the channel power-delay profile to be of certain specific types and it can operate in systems where pilot subcarriers have an irregular configuration.
摘要:
The present invention relates to a channel estimation technique for multi-carrier system which uses pilot signal to first obtain pilot subcarrier channel responses, then estimate the mean delay and the root-mean-square delay spread of the channel, and then uses interpolation to obtain the channel responses of arbitrary subcarriers. The present invention is able to perform channel estimation and to accurately estimate various channel delay parameters (such as the initial delay, the mean delay, and the root-mean-square delay spread) with very low quantity of pilot signal and with low computational complexity. In addition, the present invention has broad applicability, as it does not require the channel power-delay profile to be of certain specific types and it can operate in systems where pilot subcarriers have an irregular configuration.
摘要:
In multi-cell OFDM/OFDMA wireless communication systems, any subscriber station (SS) or mobile station (MS) that intends to enter the system needs to establish time and frequency synchronization with the base station (BS) and obtain the identification code of the BS, where in frequency synchronization one usually needs to estimate the fractional carrier frequency offset (CFO) and the integral CFO. (“Fractional” and “integral” refer to, respectively, the fractional and the integral parts of the ratio of the CFO to subcarrier spacing.) The present invention assumes that the SS or MS first does timing and fractional CFO synchronization and then conducts integral CFO estimation and BS identity detection. The present invention considers integral CFO estimation and BS identity detection jointly, i.e., it proposes solutions that address these topics jointly. The present invention formulates the problem as a signal detection problem in multi-channel interference and obtains the theoretically optimal solution first, and then derives simplified, approximately optimal solutions, in which the present invention employs frequency-domain filtering to calculate the required correlation values which can drastically reduce the high computational complexity of the original theoretically optimal solution but results in little impact on precision. In addition, the present invention proposes several further simplified algorithms, some of which can even eliminate the use of multipliers. The above proposition of frequency-domain filtering has high extensibility in application to related signal sequence detection problems.
摘要:
A method of dynamic tone grouping (DTG) used by a transmitter in a wireless OFDM system is proposed. First, a sequence of coded and interleaved bits is de-multiplexed into a number of bit-streams. Each bit-stream is mapped into a sequence of QAM symbols, which are grouped into non-overlapping sets of QAM symbols. Unitary transformation is then applied on the QAM symbols to produce groups of complex signals. Finally, the complex signals are dynamically mapped to subcarrier groups based on tone mapping information to improve link performance. The tone mapping information is derived from information associated with each OFDM subcarrier, such as channel state information (CSI). The OFDM subcarriers are grouped into subcarrier groups according to the tone mapping information such that the channel quality of each subcarrier group is balanced. In addition, the tone mapping information is efficiently encoded and transmitted to/from a corresponding receiver.
摘要:
A method of dynamic tone grouping (DTG) used by a transmitter in a wireless OFDM system is proposed. First, a sequence of coded and interleaved bits is de-multiplexed into a number of bit-streams. Each bit-stream is mapped into a sequence of QAM symbols, which are grouped into non-overlapping sets of QAM symbols. Unitary transformation is then applied on the QAM symbols to produce groups of complex signals. Finally, the complex signals are dynamically mapped to subcarrier groups based on tone mapping information to improve link performance. The tone mapping information is derived from information associated with each OFDM subcarrier, such as channel state information (CSI). The OFDM subcarriers are grouped into subcarrier groups according to the tone mapping information such that the channel quality of each subcarrier group is balanced. In addition, the tone mapping information is efficiently encoded and transmitted to/from a corresponding receiver.