Industrial automation and safety applications demand low latency and ultra reliable communication. Currently deployed wireless communication technologies are mostly developed for non-critical applications and hence, they are not suitable for these kind of applications. On the other hand, cable based communication is widely popular in industries, even though it has limitations towards cost of installment and is susceptible towards mechanical wear and tear. This paper reviews the feasibility of large antenna arrays at the receiver to achieve low latency and ultra reliable communication for up-link scenarios. The suitability of both coherent and non-coherent multiple input multiple output (MIMO) receivers are investigated. Non-coherent MIMO receiver is found to be a promising option as signal to noise power ratio (SNR) is fairly reasonable in achieving the desired reliability. The effect of antenna correlation at the transmitter and at receiver on reliability are also looked into. Its influence on the system performance is very nominal. Moreover, in certain scenarios, antenna correlation at the transmitter gives a significant improvement in system performance. Furthermore, having a single antenna at the sensors is found not to be a limiting factor in achieving the desired performance goal.

In this paper, a multi-hypothesis distributed detection technique with non-identical local detectors is investigated. Here, for a global event, some of the sensors/detectors can observe the whole set of hypotheses, whereas the remaining sensors can either see only some aspects of the global event or infer more than one hypothesis as a single hypothesis. Another possible option is that different sensors provide complementary information. The local decisions are sent over a multiple access radio channel so that the data fusion is formed in the air before reaching the decision fusion center (DFC). An optimal energy fusion rule is formulated by considering the radio channel effects and the reliability of the sensors together, and a closed-form solution is derived. A receive beamforming algorithm, based on a modification of Lozano's algorithm, is proposed to equalize the channel gains from different sensors. Sensors with limited detection capabilities are found to boost the overall system performance when they are used along with fully capable sensors. The additional transmit power used by these sensors is compensated by the designed fusion rule and the antenna array gain. Additionally, the DFC, equipped with a large antenna array, can reduce the overall transmit energy consumption without sacrificing the detection performance.

There has been very little exploration when it comes to design distributed detection techniques and data fusion rules with non-identical sensors. This concept can be utilized in many possible applications within industrial automation, surveillance and safety. Here, for a global event, some of the sensors/detectors in the network can observe the full set of the hypotheses, whereas the remaining sensors infer more than one hypotheses as a single hypothesis. The local decisions are sent to the decision fusion center (DFC) over a multiple access wireless channel. In this paper, a fusion rule based on minimization of variance of the local mis-detection is proposed. The presence of sensors with limited detection capabilities is found to have a positive impact on the overall system performance, both in terms of probability of detection and transmit power consumption. Additionally, when the DFC is equipped with a large antenna array, the overall transmit power consumption can be reduced without sacrificing the detection performance. 

In this research paper, fusion in the air (FIA) and fusion at the receiver (FAR) - two different approaches of multi-hypotheses distributed detection for wireless sensor networks with decision fusion center (DFC) - are investigated. The DFC is equipped with multiple antennas, whereas each of the sensors has a single antenna. The performance of these schemes is evaluated in two different scenarios; with identical sensors and non-identical sensors, in terms of their detection capabilities. For a global event, identical sensors observe an equal number of hypotheses, whereas the number of hypotheses detected by the non-identical sensors can be different. When all the sensors in the network are identical, the FIA based technique has a higher detection probability in transmit power constrained situations. However, the FAR scheme performs better when the transmit power budget is higher. Additionally, in the network with non-identical wireless sensors, the FAR based technique is unable to exploit the benefits from the local decisions of the low capability sensors. Therefore the FAR scheme has a lower detection probability than the FIA based approach.

This article investigates the wide-band channel characteristics at 24 GHz ISM band in a mobile radio environment. The mobility in the test environment is achieved by attaching the transmit antenna to a KUKA robot’s arm. The radio measurements were carried out inside the robotics lab at the University of Gävle, Sweden. The radio channel measurements were carried out at various situations, e.g., line of sight (LOS), non-line of sight (NLOS), regular lab environment, reflective environment, and different velocities of the robot’s arm. The influence of these situations on the power delay profile, Doppler spectral density, root mean square (RMS) delay spread, RMS Doppler spread, coherence bandwidth and coherence time, has been studied.

Millimeter wave (mmWave) frequency bands, ranging from 24 GHz to 100 GHz, are one of the candidate features of fifth generation mobile technology (5G). This article investigates the channel fading and path loss modeling in indoor industrial environments at the 24 GHz ISM band. The radio channel measurements were carried out to study the narrowband channel characteristics in three different industrial environments in Sweden. The measurements were conducted using an affordable but highly competent in-house assembled mmWavetestbed, reusing several radio instruments available in our lab. A comprehensive study is performed to investigate various radio channel propagation aspects, like the large scale fading, and the small scale fading. We examine the large scale fading with three different path loss models. The impact of the transmitter and receiver separation distance on the small scale fading is also investigated.

Millimeter wave (mmWave) wireless technology is one of the candidate features in fifth-generation mobile technology(5G) and has the potential to revolutionize the industrial automation and manufacturing processes. This article investigates multipath radio channel propagation in indoor industrial environments at one of the mmWave frequency bands. The wideband radio channel measurements at the 24 GHz ISM band were carried out in four different industrial environments in Sweden. The measurements were conducted using an affordable but highly competent in-house assembled mmWave testbed, reusing several radio instruments available in our lab. The measurement environments were chosen based on their radio wave reflection characteristics. The multipath propagation characteristics are analyzed with respect to the power delay profile (PDP), coherence bandwidth, and root mean square (RMS) delay spread. Additionally, the Saleh-Valenzuela model parameters are estimated for these industrial environments.