Christopher Mollén
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View article: Two-Layer Decoding in Cellular Massive MIMO Systems with Spatial Channel Correlation
Two-Layer Decoding in Cellular Massive MIMO Systems with Spatial Channel Correlation Open
This paper studies a two-layer decoding method that mitigates inter-cell interference in multi-cell Massive MIMO systems. In layer one, each base station (BS) estimates the channels to intra-cell users and uses the estimates for local deco…
View article: Two-Layer Decoding in Cellular Massive MIMO Systems with Spatial Channel Correlation
Two-Layer Decoding in Cellular Massive MIMO Systems with Spatial Channel Correlation Open
This paper studies a two-layer decoding method that mitigates inter-cell interference in multi-cell Massive MIMO systems. In layer one, each base station (BS) estimates the channels to intra-cell users and uses the estimates for local deco…
View article: Inverse Extrapolation for Efficient Precoding in Time-Varying Massive MIMO–OFDM Systems
Inverse Extrapolation for Efficient Precoding in Time-Varying Massive MIMO–OFDM Systems Open
Regularized zero forcing (RZF) precoding is an efficient linear precoding scheme for combating interference in a single-cell massive multiple-input-multiple-output (MIMO) systems. Inaccurate channel state information (CSI) due to channel a…
View article: Large-Scale-Fading Decoding in Cellular Massive MIMO Systems With Spatially Correlated Channels
Large-Scale-Fading Decoding in Cellular Massive MIMO Systems With Spatially Correlated Channels Open
Massive multiple-input–multiple-output (MIMO) systems can suffer from coherent intercell interference due to the phenomenon of pilot contamination. This paper investigates a two-layer decoding method that mitigates both coherent and non-co…
View article: Spatial Characteristics of Distortion Radiated From Antenna Arrays With Transceiver Nonlinearities
Spatial Characteristics of Distortion Radiated From Antenna Arrays With Transceiver Nonlinearities Open
The distortion from massive MIMO (multiple-input--multiple-output) base stations with nonlinear amplifiers is studied and its radiation pattern is derived. The distortion is analyzed both in-band and out-of-band. By using an orthogonal Her…
View article: Impact of Spatial Filtering on Distortion From Low-Noise Amplifiers in Massive MIMO Base Stations
Impact of Spatial Filtering on Distortion From Low-Noise Amplifiers in Massive MIMO Base Stations Open
In massive MIMO base stations, power consumption and cost of the low-noise amplifiers (LNAs) can be substantial because of the many antennas. We investigate the feasibility of inexpensive, power efficient LNAs, which inherently are less li…
View article: High-End Performance with Low-End Hardware: Analysis of Massive MIMO Base Station Transceivers
High-End Performance with Low-End Hardware: Analysis of Massive MIMO Base Station Transceivers Open
Massive MIMO (multiple-input–multiple-output) is a multi-antenna technology for cellular wireless communication, where the base station uses a large number of individually controllable antennas to multiplex users spatially. This technology…
View article: Spatial Characteristics of Distortion Radiated from Antenna Arrays with Transceiver Nonlinearities
Spatial Characteristics of Distortion Radiated from Antenna Arrays with Transceiver Nonlinearities Open
The distortion from massive MIMO (multiple-input--multiple-output) base stations with nonlinear amplifiers is studied and its radiation pattern is derived. The distortion is analyzed both in-band and out-of-band. By using an orthogonal Her…
View article: Achievable uplink rates for massive MIMO with coarse quantization
Achievable uplink rates for massive MIMO with coarse quantization Open
The high hardware complexity of a massive MIMO base station, which requires\nhundreds of radio chains, makes it challenging to build commercially. One way\nto reduce the hardware complexity and power consumption of the receiver is to\nlowe…
View article: Performance analysis of (TDD) massive MIMO with Kalman channel prediction
Performance analysis of (TDD) massive MIMO with Kalman channel prediction Open
In massive MIMO systems, which rely on uplink pilots to estimate the channel, the time interval between pilot transmissions constrains the length of the downlink. Since switching between up- and downlink takes time, longer downlink blocks …
View article: Out-of-Band Radiation from Large Antenna Arrays
Out-of-Band Radiation from Large Antenna Arrays Open
Co-existing wireless systems, which share a common spectrum, need to mitigate out-of-band (OOB) radiation to avoid excessive interference. For legacy systems, OOB radiation is well understood and is commonly handled by digital precompensat…
View article: Achievable Rate Analysis for Massive MIMO Base Stations with One-Bit ADCs
Achievable Rate Analysis for Massive MIMO Base Stations with One-Bit ADCs Open
MATLAB files for the computation of numerical achievable rates of the uplink of a massive MIMO system, where the base station quantizes the received signals with one-bit ADCs. The dataset was originally published in DiVA and moved to SND i…
View article: On Massive MIMO Base Stations with Low-End Hardware
On Massive MIMO Base Stations with Low-End Hardware Open
Massive MIMO (Multiple-Input Multiple-Output) base stations have proven, both in theory and in practice, to possess many of the qualities that future wireless communication systems will require. They can provide equally high data rates thr…
View article: Frequency-domain interpolation of the zero-forcing matrix in massive MIMO-OFDM
Frequency-domain interpolation of the zero-forcing matrix in massive MIMO-OFDM Open
We consider massive multiple input multiple output (MIMO) systems with orthogonal frequency division multiplexing (OFDM) that use zero-forcing (ZF) to combat interference. To perform ZF, large dimensional pseudo-inverses have to be compute…
View article: Waveforms for the Massive MIMO Downlink: Amplifier Efficiency, Distortion, and Performance
Waveforms for the Massive MIMO Downlink: Amplifier Efficiency, Distortion, and Performance Open
In massive multiple-input multiple-output (MIMO), most precoders result in downlink signals that suffer from high peak-to-average ratio (PAR), independently of modulation order and whether single-carrier or orthogonal frequency-division mu…
View article: One-bit ADCs in wideband massive MIMO systems with OFDM transmission
One-bit ADCs in wideband massive MIMO systems with OFDM transmission Open
We investigate the performance of wideband massive MIMO base stations that use one-bit ADCs for quantizing the uplink signal. Ourmain result is to show that the many taps of the frequency-selective channel make linear combiners asymptotica…
View article: Performance of the Wideband Massive Uplink MIMO with One-Bit ADCs
Performance of the Wideband Massive Uplink MIMO with One-Bit ADCs Open
Analog-to-digital converters (ADCs) consume a significant part of the total power in a massive MIMO base station. One-bit ADCs are one way to reduce power consumption. This paper presents an analysis of the spectral efficiency of single-ca…
View article: Multiuser MIMO precoding with per-antenna continuous-time constant-envelope constraints
Multiuser MIMO precoding with per-antenna continuous-time constant-envelope constraints Open
A transmission scheme for the multiuser MIMO downlink, where the transmit signal from each antenna has constant envelope and a limited bandwidth, is proposed in order to enable the use of highly efficient, nonlinear amplifiers at the base …