Mohamad Omar Al Kalaa

Evaluating Bluetooth Low Energy in realistic wireless environments

The 2.4 GHz ISM band is crowded with a wide variety of wireless devices operating under various access protocols, Bluetooth Low Energy (BLE) among them. Low power requirements, low cost, and ease of integration have promoted BLEs rapidly growing popularity. BLE applications range from providing wireless interface for monitoring household equipment status to reporting critical information from medical devices that might have less tolerance for transmission errors to function properly. In this paper, we identify risks in a real world wireless environment that adversely affect BLE system functionality. We also propose a methodology utilizing spectrum surveys to quantify probability of transmission failure relative to the systems interference detection threshold. Spectrum surveys were conducted in a basketball sport facility, a university student union and a hospital intensive care unit (ICU). Results demonstrate how a BLE system selects data transmission channels in the presence of interference. Moreover, findings of this study confirm that a BLE system is able to maintain a low probability of failed transmission while operating in the presence of high interference unless the environment noise floor is close to the employed interference detection threshold.

Bluetooth standard v4.1: Simulating the Bluetooth low energy data channel selection algorithm

Bluetooth Low Energy (BLE) is gaining notoriety as a low cost and low energy standard for wireless communication in the ISM band. The technology has been adapted in a wide range of applications, including smartphones, medical devices, and electrical household equipment. BLE introduces a simplified channel-hopping algorithm as an alternative to Classic Bluetooth - one that masks unfair usage of available spectrum. This paper details a simulation of BLEs data channel selection algorithm. The authors describe a pseudo-code for simulation software to calculate selection probability for each data channel. Results demonstrate that data channels in a BLE system are not selected equitably and the algorithm is more inclined to select data channels with indices between 1 and 21. The probability of collision between multiple BLE communicating pairs is found to be higher than that of Classic Bluetooth which results in a reduced maximum achievable aggregate throughput of 3.18 Mbps.

Vehicle classification accuracy of AVC and WIM sites in Oklahoma

Vehicle classification is a vital measure used to ensure appropriate roadway design as it affects both capacity and pavement endurance. Given that, departments of transportation across the US collect vehicle miles travelled (VMT) for their highways using automatic vehicle classifiers (AVC), and then use these figures for future highway design. Accuracy assessment of AVCs is thus important to ensure proper VMT reporting. Studying the accuracy of AVC devices is therefore essential. Previous studies employed either manual counting or a “play and pause” method of traffic video recording to verify the accuracy of AVC devices. This paper details a custom vision-aided software developed to aid in extracting accurate vehicle count and classification information used as ground truth data. Authors discuss the methodology used to study vehicle classification accuracy of AVC and weigh-in-motion sites tasked with vehicle classification. Several indicators introduced to investigate the accuracy of each site are highlighted. Results of a year-long 2013 study indicate a good performance of AVC devices and that the main source of error was the misclassification of class 2 and 3 vehicles as class 5.

Development of measurement techniques and tools for coexistence testing of wireless medical devices

The 2.4 GHz ISM band is crowded with a wide variety of wireless devices operating under various protocols. For many reasons, medical device manufacturers are increasingly incorporating wireless technologies into their devices, many of which operate in the ISM band. Monitoring and characterizing wireless spectrum utilization is vital to better plan wireless network deployments and to assess the risk of interference. This work introduces measurement techniques and tools to aid in providing reliable spectrum utilization characterization for coexistence testing of wireless medical devices. Measurements obtained from developed tools can help the US Food and Drug Administration (FDA) and medical device manufacturers to gain a better understanding of expected interference factors. Wireless medical device testing with these tools could ensure a reliable device that will enhance patient safety and accelerate introducing innovative wireless medical devices to market.

Energy detection and machine learning for the identification of wireless MAC technologies

ISM spectrum is becoming increasingly populated with various wireless technologies, rendering it a scarce resource. Consequently, wireless coexistence is increasingly vulnerable to new wireless devices attempting to access the same spectrum. This paper presents a novel method for identifying wireless technologies through the use of simple energy detection techniques. Energy detection is used to measure the channel statistical temporal characteristics including activity and inactivity probability distributions. Features uniquely belonging to specific wireless technologies are extracted from the probability distributions and fed into a machine-learning algorithm to identify the technologies under evaluation. Wireless technology identification enables situational awareness to improve coexistence and reduce interference among the devices. An intelligent wireless device is capable of detecting wireless technologies operating within same vicinity. This can be performed by scanning energy levels without the need for signal demodulation and decoding. In this work, a wireless technology identification algorithm was assessed experimentally. Temporal traffic pattern for 802.11b/g/n homogeneous and heterogeneous networks were measured and used as algorithm input. Identification accuracies of up to 96.83% and 85.9% were achieved for homogeneous and heterogeneous networks, respectively.

Bluetooth and IEEE 802.11n System Coexistence in the Automotive Domain

Connected cars have telecommunication services similar to those found in homes and offices. Passengers have come to expect efficiently using time spent in their cars working and engaging in entertainment. Fulfilling this desire requires advanced infotainment systems with a variety of capabilities and functions similar to mobile phones. As people become more attached to their mobile phones, seamless integration of phones into the car computer becomes more crucial. Bluetooth and IEEE 802.11 systems are often used to connect mobile phones to car computers. Both technologies operate in the 2.4 GHz unlicensed industrial, scientific and medical (ISM) radio bands. However, since early development of standards governing the ISM band, coexistence among devices sharing the band have been under close scrutiny. An increased use of Bluetooth and 802.11 systems in the automotive domain and the logistics of having extremely small distances between devices makes coexistence a challenging task. This paper presents performance evaluation of both WLAN and Bluetooth for typical automotive domain applications (i.e., music streaming and hands-free calling). Focused attention is paid to a scenario in which all three non overlapped WLAN channels are used. The effect of traffic load and WLAN power level are investigated. Results demonstrate that Bluetooth channels 71 to 78 are critical to maintain acceptable Bluetooth connectivity. Hands-free calling is more sensitive to interference than music streaming. Bluetooth effect on WLAN is small.

Selection probability of data channels in Bluetooth Low Energy

Bluetooth Low Energy (BLE) is a ubiquitous technology allowing applications in healthcare, wellness and house-hold sensors to have wireless functionality. Even though a frequency hopping mechanism is employed by BLE to combat fading and interference in the 2.4 GHz Industrial, Scientific and Medical (ISM) band, a noticeable probability of collision is expected to arise when the number of communicating BLE devices in the same vicinity increases. In this paper, an analytical model to find the selection probability of each of the 37 BLE data channels is presented. The results, which are confirmed by brute-force simulation, are then used to find the probability of collision between collocated BLE pairs and their maximum achievable aggregate throughput.

IEEE 802.11 Systems in the Automotive Domain: Challenges and Solutions.

Customer demand for infotainment systems has garnered great attention from car manufacturers. System features have become a decisive factor when choosing among car models. As consumers become more dependent on their portable electronic devices (e.g., mobile phones, tablets), they expect to have seamless integration of their devices inside their cars. This allows them to use the same features supported by their phones in the cars. Car manufacturers aim to make their infotainment systems user-friendly. A key factor to achieve this goal is facilitating a wireless connection between mobile phones and car computers. IEEE 802.11 systems are the most popular candidate to provide high data rate connections utilizing the unlicensed industrial, scientific and medical (ISM) radio band. However, due to the limited available spectrum and the high density of devices inside the car, the achieved throughput could be strongly affected by interference and coexistence challenges. Furthermore, strong interference between the networks in different cars plays a crucial role in the automotive domain. This paper highlights the interference problem between IEEE 802.11 systems in cars. Two solutions in the 802.11n standard, namely transmission power control (TPC) and multiple input multiple output (MIMO) techniques, are discussed. Results show that both techniques could improve system performance. Transmission power control is essential to control radiation to surrounding environment.

mmWave based vs 2 GHz networks: What is more energy efficient?

The demand for increasingly challenging data rates in cellular networks has motivated the pursuit to exploit abundant bandwidth at the millimeter waves (mmWave) spectrum, which offers large bandwidths and near free-space path loss for line of sight links. However, this solution comes at the cost of limited communication range. Thus, mmWave basestations (BS) are expected to be densely deployed to maximize offered service. As the energy consumed in a network is roughly proportional to the number of nodes, how energy efficient a mmWave network will be is a question that remains unanswered so far. In this paper, we compare the performance of mmWave cellular networks in terms of energy efficiency (EE) to that of networks operating at 2 GHz. We start from the link budget to determine the average cell radius of two mmWave systems operating at 28 GHz and 60 GHz. Afterwards, intensity of a Poisson Point Process that models mmWave BS locations pertaining to expected operational network parameters is calculated. The probability of coverage offered by investigated systems is evaluated using analytical expressions. Finally, EE is calculated using consumed power model that assumes actual mmWave components. Results suggest that when the deployment environment allows for high signal to interference and noise ratio (SINR) to be achieved at the receiver, mmWave system EE outperforms a 2 GHz system. Conversely, when only low SINR is achievable, 2 GHz system EE is superior to mmW system.

On the performance of WLAN and Bluetooth for in-car infotainment systems

Abstract The connected car is ushering in a new era of automotive design. Driven by increasing customer demand for connectivity and advances in electronics, connected cars are now equipped with advanced infotainment systems with a variety of applications. Seamless integration of consumer electronic (CE) devices into car infotainment systems is crucial for mimicking home and office user experience. Because wireless communication is more user-friendly than wired communication, it has become the preferred method for connecting CE devices to car infotainment systems. WLAN 1 and Bluetooth 2 are the most promising technologies for this purpose. Both systems operate in the spectrum-scarce 2.4 GHz unlicensed industrial, scientific and medical (ISM) radio band. The coexistence between WLAN and Bluetooth has garnered a significant amount of attention from both academic and industry researchers. However, the unique features of vehicle mobility and the high density of devices in a limited roadway area necessitate further investigation in the automotive domain. This paper focuses on the coexistence between WLAN and Bluetooth systems among vehicle infotainment applications, and on WLAN co-channel interference. Performance is evaluated using experimental measurements in real-world scenarios. The mobility effect is studied in detail. Results show that an onboard WLAN network is strongly affected by the surrounding networks. Coexistence duration decreases exponentially with relative speed between automobile networks. WLAN effect on Bluetooth is extremely high when WLANs non-overlapped channels 1, 6, and 11 are simultaneously occupied. WLAN interference leads to a significant number of clippings in Bluetooth audio signals, especially in high WLAN traffic load situations. An exponential decease in the number of clipping events as a function of speed is observed.