Qualcomm Incorporated

Daniel T Macek

Tao Luo

Peter S Gaal

Yongbin Wei

Durga Prasad Malladi

Dung Ngoc Doan

Ke Liu

Lennart Karl Mathe

Hanfang Pan

Wei-Jei Song

Robert Fuchs

Methods, systems, apparatus and computer program products are provided to improve synchronization of information units communicated in a wireless communication system. Timing misalignment in the transmission of adjacent information units can produce gaps or overlaps in the transmitted information. In a long-term evolution (LTE) wireless communication system, such gaps and overlaps can be eliminated or reduced by adjusting the lengths of a cyclic prefix portion of one or more transmitted symbols. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the disclosed subject matter. Therefore, it is to be understood that it should not be used to interpret or limit the scope or the meaning of the claims.

Timing adjustments in a communication system

Efficient apparatus and method for Zadoff-Chu ('Chu') sequence generation avoids additional processing and hardware complexity of conventional quadratic generating formula followed by Discrete Fourier Transform (DFT) with a reference signal generator that produces both a Zadoff-Chu sequence and its DFT. In the wireless communication system (e.g., Long Term Evolution (LTE) system), Chu sequences are extensively used, especially in the uplink (UL). Because of the single carrier operating mode, transmitting a Chu sequence in principle involves a succession of generating that sequence, performing a DFT operation and then an IFFT operation. Assuming that the sequence length is N, the initial sequence generation requires 2N multiplications and the DFT requires more than N log 2(N) multiplications. Given the frequent processing of Chu sequences, this would represent a complexity burden. The invention makes it possible to perform the sequence generation and DFT steps without any multiplication operation, except for possibly calculating certain initial parameters.

Efficient zadoff-chu sequence generation

A low power sample rate converter adapted for use with a telecommunications system transceiver. The sample rate converter includes a first circuit that provides an input signal characterized by a first sample rate and a delayed version of the input signal. A second circuit periodically multiplies, at a second sample rate, samples in the input signal by a first predetermined coefficient in accordance with a predetermined transfer function and provides a first signal in response thereto. A third circuit periodically multiplies, at the second sample rate, samples in the delayed version of the input signal by a second predetermined coefficient in accordance with the predetermined transfer function and provides a second signal in response thereto. A fourth circuit combines the first signal and second signal providing a rate-converted version of the input signal as an output signal in response thereto. In a specific embodiment, the delayed version of the input signal is delayed by one sample with respect to the input signal. The sample rate converter further includes a counter that is clocked by a first periodic signal. The first periodic signal has a frequency related to the first sample rate by a predetermined fraction. The counter is cleared by a second periodic signal having a second frequency equivalent to the first sample rate. The counter produces a counter output at the first frequency. In the preferred embodiment, the predetermined fraction is &frac13; and the first predetermined coefficient is equivalent to the sum of 1 and the counter output. The second predetermined coefficient is equivalent to the difference of 2 and the counter output. The fourth circuit includes an adder for adding the first signal and the second signal and providing the output signal in response thereto. The predetermined transfer function is represented by the following coefficient sequence: &lsqb;1 2 3 2 1&rsqb;.

Low-current sample rate converter

Growing community of inventors

San Diego, CA, United States of America

Daniel T Macek