Space-Time Block Coding for Wireless Communications

A system comprises a modulator circuit, a test signal generator circuit, and a control circuit. The modulator circuit is operable to generate a data-carrying signal based on a reference signal. The test signal generator circuit is operable to generate a test signal based on the reference signal. The control circuit is operable to determine current status of a microwave backhaul link. The control circuit is operable to configure a nominal frequency at which the test signal generator circuit generates the test signal based on the determined status of the microwave backhaul link. The control circuit is operable to determine an amount of whitespace to have on either side of the test signal based on the current status of the microwave backhaul link. The control circuit is operable to configure the modulator circuit such that the data-carrying signal has the determined amount of whitespace surrounding the nominal frequency of the test signal.

Phase noise suppression

A bidirectional repeater for repeating an electrical signal traversing a conductive line coupled between a gateway node and a sensor, the bidirectional repeater comprising a first input-output port coupled to the gateway node, a second input-output port coupled to the sensor, a first transceiver configured to receive a synchronization signal from the first input-output port and to transmit a re synchronized data signal to the first input-output port, a second transceiver configured to transmit the synchronization signal to the second input-output port and to receive a data signal from the second input-output port, and a repeater circuit coupled to the first and second transceivers and configured to pass through the synchronization signal, and to resynchronize the data signal to generate the resynchronized data signal.

Extendable synchronous low power telemetry system for distributed sensors

This disclosure relates to channel assessment and selection for wireless communication between two or more medical devices, such as between an implantable medical device (IMD) and a non-implanted medical device, between two IMDs, or between two non-implanted medical devices. A telemetry module of a medical device operating in accordance with the techniques of this disclosure obtains measured ambient power levels on a plurality of channels of a frequency band regulation, such as the ten channels of the MICS band regulation. The telemetry module computes channel assessment values for at least a portion of the plurality of channels based on the measured ambient power levels on at least one other channel of the plurality of channels and selects a channel to transmit on based on the channel assessment values.

Channel assessment and selection for wireless communication between medical devices

http://ieeexplore.ieee.org/iel5/5/31341/01457276.pdf

Parameter estimation: Principles and problems

Several wireless network systems are disclosed. In an embodiment, a wireless network system includes at least two access points and a distributed set of devices communicatively associated with the at least two access points. Each device from among the distributed set of devices comprises a pair of wireless stations and each wireless station from among the pair of wireless stations is configured to transmit data associated with an alert situation to a distinct access point from among the at least two access points. A communication between one or more access points from among the at least two access points and one or more wireless stations from among the pairs of wireless stations corresponding to the distributed set of devices is synchronized based on a timing synchronization information shared by at least two basic service sets (BSSs) corresponding to the at least two access points.

Wireless network systems

In this paper we study the effect of random jitter in the sampling circuit at the receiver in an OFDM communication system. We show that the effect of jitter can be looked at as interference between different sub-carriers and derive a lower bound for the variance of the interference in terms of the eigenvalues of the covariance matrix of the jitter process. We compare the results with simulation results. We describe the effect of oversampling on the interference, and provide an explanation for the way interference varies with sub-carrier index for different sampling rates.

The effect of sampling jitter in OFDM systems

In this paper, we present novel precoding methods for multiuser Rayleigh fading multiple-input–multiple-output (MIMO) systems when channel state information (CSI) is available at the transmitter (CSIT) but not at the receiver (CSIR). Such a scenario is relevant, for example, in time-division duplex (TDD) MIMO communications, where, due to channel reciprocity, CSIT can be directly acquired by sending a training sequence from the receiver to the transmitter(s). We propose three transmit precoding schemes that convert the fading MIMO channel into a fixed-gain additive white Gaussian noise (AWGN) channel while satisfying an average power constraint. We also extend one of the precoding schemes to the multiuser Rayleigh fading multiple-access channel (MAC), broadcast channel (BC), and interference channel (IC). The proposed schemes convert the fading MIMO channel into fixed-gain parallel AWGN channels in all three cases. Hence, they achieve an infinite diversity order, which is in sharp contrast to schemes based on perfect CSIR and no CSIT, which, at best, achieve a finite diversity order. Further, we show that a polynomial diversity order is retained, even in the presence of channel estimation errors at the transmitter. Monte Carlo simulations illustrate the bit error rate (BER) performance obtainable from the proposed precoding scheme compared with existing transmit precoding schemes.

Novel Transmit Precoding Methods for Rayleigh Fading Multiuser TDD-MIMO Systems With CSIT and No CSIR

Selecting one of multiple antennas to receive signals in a wireless packet network. Correlation value and gain needed to boost the signal up to a desired power (or the signal strength of the received signal) are determined for each antenna by examining the non-payload portion (e.g., preamble) of the packet. The antenna with the best SNR is then chosen based on the rule given. In an embodiment, the correlation value is determined based on the Barker Sequence employed for each bit in the preamble. The selection may be performed for each data packet, thereby using the antenna receiving the signal most conducive to recovery of the data bits (including payload) in each data packet.

Selecting One of Multiple Antennas to Receive Signals in a Wireless Packet Network

This paper describes RF Built-in Self Test (BiST) techniques to test the performance of a RF CMOS integrated wireless transceiver using on-chip digital resources as both the stimuli and response analyzer. Using a defect-oriented approach, key RF blocks as well as the overall functionality and performance of the device are analyzed using a combination of block level and loopback testing. Using these methods, contributors to Error Vector Magnitude (EVM) such as amplifier gain, phase noise, and linearity performance (IP3) can be estimated and collected to predict the functional performance of a Digital Radio Processor (DRP) for wireless applications.

Ganesan Thiagarajan

Papers

Wireless network systems

The effect of sampling jitter in OFDM systems

Novel Transmit Precoding Methods for Rayleigh Fading Multiuser TDD-MIMO Systems With CSIT and No CSIR

Selecting One of Multiple Antennas to Receive Signals in a Wireless Packet Network

Novel BiST methods for parametric test in wireless transceivers