Mads Lauridsen

LTE UE Power Consumption Model: For System Level Energy and Performance Optimization

In this work a novel LTE user equipment (UE) power consumption model is presented. It was developed for LTE system level optimization, because it is important to understand how network settings like scheduling of resources and transmit power control affect the UEs battery life. The proposed model is based on a review of the major power consuming parts in an LTE UE radio modem. The model includes functions of UL and DL power and data rate. Measurements on a commercial LTE USB dongle were used to assign realistic power consumption values to each model parameter. Verification measurements on the dongle show that the model results in an average error of 2.6 %. The measurements show that UL transmit power and DL data rate determines the overall power consumption, while UL data rate and DL receive power have smaller impact.

Centimeter-Wave Concept for 5G Ultra-Dense Small Cells

Ultra-dense small cells are foreseen to play an essential role in the 5th generation (5G) of mobile radio access technology, which will be operating over different bands with respect to established systems. The natural step for exploring new spectrum is to look into the centimeter-wave bands as well as exploring millimeter-wave bands. This paper presents our vision on the technology components for a 5G centimeter-wave concept for ultra-dense small cells. Fundamental features such as optimized short frame structure, multi-antenna technologies, interference rejection, rank adaptation and dynamic scheduling of uplink/downlink transmission are discussed, along with the design of a novel flexible waveform and energy-saving enablers.

Achieving low latency and energy consumption by 5G TDD mode optimization

The target for a new 5G radio access technology is to support multi-Gbps and ms latency connectivity simultaneously at noticeably lower energy consumption and cost compared to the existing 4G technologies, such as LTE-Advanced. Extremely short air interface latency is required to achieve these requirements in a TDD-based local area network. In this paper, we discuss how the required short TDD latency can be achieved and further utilized in 5G physical air interface. First, we investigate the enablers and limits of TDD latency by analyzing the performance of OFDM in different channel environments and discussing on the consequent frame length limits. We then provide a description on how the achieved short TDD latency can further be utilized to enable remarkably low energy consumption. A numerical analysis comparing the battery life time of the suggested 5G TDD air interface and LTE is provided, showing remarkable gains for the 5G air interface concept.

Reducing LTE Uplink Transmission Energy by Allocating Resources

The effect of physical resource block (PRB) allocation on an LTE modems transmit power and total modem energy consumption is examined. In this paper the uplink resource blocks are scheduled in either a Frequency Division Multiple Access (FDMA) or Time Division Multiple Access (TDMA) manner, to determine if low transmission power & long transmission time or high transmission power & short transmission time is most energy efficient. It is important to minimize the LTE modems energy consumption caused by uplink transmission because it affects phone battery time, and because researchers rarely focus on energy consumption when they optimize network controlled uplink transmission power parameters. Simulations based on a simple traffic model and a power consumption model show the TDMA scheme, where one user is allocated all 48 PRBs in a 10 MHz channel, is at least 24 % more energy efficient than the FDMA like approach with 8 PRBs per user. Furthermore the TDMA scheme decreases the average transmission time with minimum 24 %.

Deployment and implementation strategies for massive MIMO in 5G

Massive MIMO has emerged as one technology enabler for the next generation mobile communications 5G. The gains promised by massive MIMO are augured to overcome the capacity crunch in todays mobile networks and to pave the way for the ambitious targets of 5G. The challenge to realize massive MIMO for 5G is a successful and cost-efficient integration in the overall network concept. This work highlights deployment and implementation strategies for massive MIMO in the context of 5G indoor small cell scenarios. Different massive MIMO deployment scenarios are analyzed for a standard 3GPP indoor office scenario. In particular stand-alone MIMO at a single location, distributed MIMO without cooperation and network MIMO with full cooperation are investigated for varying array configurations. For the performance analysis of the different MIMO configurations the ratio of total transmit antennas to spatial streams is varied stepwise from equality to a factor of ten. For implementation of massive MIMO in 5G networks trends in beamforming techniques, mutually coupled subarrays, over the calibration procedure and estimated ADC performance in 2020 time-frame are discussed. Based on the debate the paper indicates how to integrate large-scale arrays in future 5G networks.

Signal Quality Outage Analysis for Ultra-Reliable Communications in Cellular Networks

Ultra-reliable communications over wireless will open the possibility for a wide range of novel use cases and applications. In cellular networks, achieving reliable communication is challenging due to many factors, particularly the fading of the desired signal and the interference. In this regard, we investigate the potential of several techniques to combat these main threats. The analysis shows that traditional microscopic multiple-input multiple-output schemes with 2×2 or 4×4 antenna configurations are not enough to fulfil stringent reliability requirements. It is revealed how such antenna schemes must be complemented with macroscopic diversity as well as interference management techniques in order to ensure the necessary SINR outage performance. Based on the obtained performance results, it is discussed which of the feasible options fulfilling the ultra-reliable criteria are most promising in a practical setting, as well as pointers to supplementary techniques that should be included in future studies.

Coverage and Capacity Analysis of LTE-M and NB-IoT in a Rural Area

The 3GPP has introduced the LTE-M and NB-IoT User Equipment categories and made amendments to LTE release 13 to support the cellular Internet of Things. The contribution of this paper is to analyze the coverage probability, the number of supported devices, and the device battery life in networks equipped with either of the newly standardized technologies. The study is made for a site specific network deployment of a Danish operator, and the simulation is calibrated using drive test measurements. The results show that LTE-M can provide coverage for 99.9 % of outdoor and indoor devices, if the latter is experiencing 10 dB additional loss. However, for deep indoor users NB-IoT is required and provides coverage for about 95 % of the users. The cost is support for more than 10 times fewer devices and a 2-6 times higher device power consumption. Thus both LTE-M and NB- IoT provide extended support for the cellular Internet of Things, but with different trade- offs.

Automation for On-Road Vehicles: Use Cases and Requirements for Radio Design

The support of mission-critical communication (MCC) opens the possibility to implement a broad range of novel applications. V2X communication for traffic safety and automation is, among others, one of these innovative applications expected to bring big benefits to society: accidents are prevented, driving times are reduced, and carbon dioxide is saved. In this regard, we first present a system model and fundamental definitions of reliability, latency and availability. Relying on these definitions, a systematic review of requirements for the huge variety of V2X applications is provided, including insights into the expected evolution towards autonomous driving. The many challenges introduced by V2X use cases are emphasized and compared to todays wireless system capabilities. Finally, we give our vision on the design of future radio technologies for the support of this kind of communications.

Interference Measurements in the European 868 MHz ISM Band with Focus on LoRa and SigFox

In this measurement study the signal activity and power levels are measured in the European Industrial, Scientific, and Medical band 863-870 MHz in the city of Aalborg, Denmark. The target is to determine if there is any interference, which may impact deployment of Internet of Things devices. The focus is on the Low Power Wide Area technologies LoRa and SigFox. The measurements show that there is a 22-33 % probability of interfering signals above -105 dBm within the mandatory LoRa and SigFox 868.0-868.6 MHz band in a shopping area and a business park in downtown Aalborg, which thus limits the potential coverage and capacity of LoRa and SigFox. However, the probability of interference is less than 3 % in the three other measurement locations in Aalborg. Finally, a hospital and an industrial area are shown to experience high activity in the RFID subband 865-868 MHz, while the wireless audio band 863-865 MHz has less activity.

From LTE to 5G for Connected Mobility

Long Term Evolution, the fourth generation of mobile communication technology, has been commercially deployed for about five years. Even though it is continuously updated through new releases, and with LTE Advanced Pro Release 13 being the latest one, the development of the fifth generation has been initiated. In this article, we measure how current LTE network implementations perform in comparison with the initial LTE requirements. The target is to identify certain key performance indicators that have suboptimal implementations and therefore lend themselves to careful consideration when designing and standardizing next generation wireless technology. Specifically, we analyze user and control plane latency, handover execution time, and coverage, which are critical parameters for connected mobility use cases such as road vehicle safety and efficiency. We study the latency, handover execution time, and coverage of four operational LTE networks based on 19,000 km of drive tests covering a mixture of rural, suburban, and urban environments. The measurements have been collected using commercial radio network scanners and measurement smartphones. Even though LTE has low air interface delays, the measurements reveal that core network delays compromise the overall round-trip time design requirement. LTEs breakbefore- make handover implementation causes a data interruption at each handover of 40 ms at the median level. While this is in compliance with the LTE requirements, and lower values are certainly possible, it is also clear that break-before-make will not be sufficient for connected mobility use cases such as road vehicle safety. Furthermore, the measurements reveal that LTE can provide coverage for 99 percent of the outdoor and road users, but the LTE-M or NarrowBand-IoT upgrades, as of LTE Release 13, are required in combination with other measures to allow for additional penetration losses, such as those experienced in underground parking lots. Based on the observed discrepancies between measured and standardized LTE performance, in terms of latency, handover execution time, and coverage, we conclude the article with a discussion of techniques that need careful consideration for connected mobility in fifth generation mobile communication technology.