Next Generation Wireless Lans 802 11n And 802 11ac

A system and method of auto-detection of WLAN packets includes selecting a first Golay sequence from a first pair of Golay complementary sequences associated with first packet type, each Golay sequence of the first pair of Golay complementary sequences being zero correlation zone (ZCZ) sequences with each Golay sequence of a second pair of Golay complementary sequences associated with a second packet type, and transmitting a wireless packet carrying a short training field (STF) that includes one or more instances of the first Golay sequence.

System and method for auto-detection of WLAN packets using STF

Provided is a next-generation wireless local area network (WLAN) frame communication method. The communication method may include modulating a first symbol in a signal field A (SIG-A) of a next-generation WLAN frame using a first modulation method, modulating a second symbol in the SIG-A of the next-generation WLAN frame using a second modulation method, and modulating a short training field (STF) signal of the next-generation WLAN frame in response to a next-generation WLAN mode.

Multi-mode wireless transmission method and apparatus

MU-MIMO transmission relies on exploiting multi-user diversity among a multitude of users. In this paper, to enhance MU-MIMO transmission, techniques for designing and exploiting reconfigurable antennas (RAs) are developed. A single-element RA is capable of generating modes with different radiation pattern and polarization states resulting in multiple different channel states for each user. This capability expands the search space for user-pairing optimization. To reduce complexity, an iterative user and antenna mode selection algorithm is proposed. Based on parasitic tuning, an RA optimized for MU-MIMO transmission and capable of creating four pattern types is designed using a genetic algorithm and full-wave electromagnetic analyses. Pattern- and channel-aware mode-set generation methods are developed, where mode groups are determined to reduce channel estimation overhead and mode selection complexity while achieving superior performance. Simulation results indicate that the proposed schemes need a lower number of users and/or relax user selection requirements to benefit from MU-MIMO transmissions. It is also seen that more legacy antennas are needed to achieve similar MU-MIMO performance provided by the RA system. Simulations show up to 16-dB signal-to-noise ratio gains for a single cell with 12 users, where the base station has four RAs and four single-antenna users are simultaneously served via MU-MIMO transmission.

Downlink Multi-User MIMO Transmission for Radiation Pattern Reconfigurable Antenna Systems

Aspects of the disclosure relate to next generation (e.g., fifth generation or 5G) cells that support legacy radio access technologies by sharing a carrier between 5G and legacy transmissions. To facilitate coexistence between legacy and 5G transmissions, a configurable slot structure may be utilized for 5G transmissions. The configurable slot structure may be configured to have an effective duration that prevents transmission thereof during at least a portion of a control region of a legacy subframe. Other aspects, embodiments, and features are also claimed and described.

Legacy and new radio coexistence frame and control design

A method of estimating a symbol boundary for adaptive time synchronization in a communication system is presented. An embodiment of the method includes receiving a signal comprising a plurality of OFDM symbols from receiver chains. The OFDM symbols include at least a long training field (LTF) symbol. The method further includes determining a normalized correlation signal based on correlation between the received LTF symbol and a reference symbol for each of the receiver chains for different lags. Also, the method includes estimating an energy window length for the normalized correlation signal. The energy window length includes at least one of channel delay spread and a maximum cyclic shift applied to the signal. The method then includes estimating the symbol boundary associated with the received LTF symbol based on a position of peak energy of the normalized correlation signal using the estimated energy window length.

System and method for adaptive time synchronization

A method for detecting a format of a frame in a communication system is presented. An embodiment of the method includes receiving the frame comprising a plurality of orthogonal frequency division multiplexing (OFDM) symbols. The plurality of OFDM symbols may include at least one signal field symbol. The method further includes determining a modulation associated with the at least one signal field symbol. The modulation may be a first modulation or a second modulation. Also, the method includes estimating a position of the at least one signal field symbol among the plurality of symbols, and extracting a coding rate of the received frame. The method then includes detecting the format of the received frame based on the determined modulation and the estimated position of the at least one signal field symbol, and the extracted coding rate of the received frame.

System and method for detecting a frame format

There has been increased demand for throughput in wireless communication systems in the past few decades Orthogonal frequency division multiplexing (OFDM) combined with multiple input multiple output (MIMO) technology has been employed in many wireless standards including wireless LAN to achieve large throughput To detect the streams of data symbols, various MIMO decoding schemes such as maximum likelihood (ML), zero forcing (ZF) and minimum mean squared error (MMSE) have been developed These schemes provide hard data bits that have to be passed through a forward error correction (FEC) decoder The performance of FEC decoder is improved by the use of soft information for each input bit Therefore, it is desirable to employ a practical soft MIMO demapper at the receiver to provide the soft information in the form of log likelihood ratios (LLR's) for each data bit that is passed through the FEC decoder In This paper, we propose a soft MIMO demapper based on ZF and MMSE equalizers We compare the performance and the complexity of the proposed method with that of existing methods using simulations It is evident from the simulation results that the proposed method is suitable for the practical implementation in a wireless communication system such as wireless LAN

A soft-demapper for coded MIMO-OFDM system

Methods, apparatuses and systems for identifying a channel bandwidth and channel offset of an orthogonal frequency division multiplexing (OFDM) signal. The OFDM signal is received by a receiver apparatus that may be tuned to RF bandwidth of 20 MHz, 40 MHz or 80 MHz. The method utilized by the apparatus includes identifying the location of the primary channel and subsequently determining a sequence of equalized frequency domain sub-symbols of the signal field in the lower and the upper frequency band. Further, a cross-correlation between the sequence of equalized frequency domain sub-symbols is computed along with the computing energy of the sequence of equalized frequency domain sub-symbols. Finally, the cross-correlation and the computed energy are compared for identifying the channel offset and the channel bandwidth.

Method and apparatus for identifying channel bandwidth and channel offset of an orthogonal frequency division multiplexing signal

In this paper, we consider a downlink multiuser multiple-input–multiple-output (MU-MIMO) system with multiple antennas at the transmitter and multiple antennas at each user, where the transmitter can send one or more data streams to each user. We propose a non-iterative method by combining Tomlinson–Harashima precoding (THP) with pre- and post-processing and selecting processing vectors based on the maximization of instantaneous signal-to-noise ratio (SNR) of the data stream at the input of the detector of each user. The postprocessing vectors for all users are found to be eigenvectors corresponding to the maximum eigenvalue of a certain matrix involving the channel matrix of the user. The transmitter computes the vectors of the linear processing matrix through an orthonormalization procedure in a single step. The feedback matrix at the transmitter is then obtained from the effective channel matrix and the linear processing matrix. We express the instantaneous SNR of all data streams in terms of eigenvalues of a Wishart matrix, obtained from the channel matrix of the user, and find the diversity order for each data stream. Considering multiple scenarios, we find the outage probability of the instantaneous SNR for all data streams and the cumulative distribution function (cdf) of the sum-rate capacity for all users using the proposed method and compare the results with those of recently proposed methods that provide a closed-form solution and with that of block diagonalization, channel inversion, and THP in scenarios where they are applicable.

Nanda Kishore Chavali

Papers

System and method for adaptive time synchronization

System and method for detecting a frame format

A soft-demapper for coded MIMO-OFDM system

Method and apparatus for identifying channel bandwidth and channel offset of an orthogonal frequency division multiplexing signal

Downlink MU-MIMO With THP Combined With Pre- and Post-processing and Selection of the Processing Vectors for Maximization of Per-Stream SNR