Showing papers by "Preben Mogensen published in 2016"

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

Abstract: 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.

A flexible 5G frame structure design for frequency-division duplex cases

Abstract: A 5G frame structure designed for efficient support of users with highly diverse service requirements is proposed. It includes support for mobile broadband data, mission-critical communication, and massive machine communication. The solution encompasses flexible multiplexing of users on a shared channel with dynamic adjustment of the transmission time interval in coherence with the service requirements per link. This allows optimizing the fundamental tradeoffs between spectral efficiency, latency, and reliability for each link and service flow. The frame structure is based on in-resource physical layer control signaling that follows the corresponding data transmission for each individual user. Comparison against the corresponding LTE design choices shows attractive benefits.

Generalized DFT-Spread-OFDM as 5G Waveform

Abstract: This article introduces G-DFT-s-OFDM as a potential 5G waveform candidate. G-DFT-sOFDM replaces the CP with a sequence having a tunable length; this sequence is part of the IFFT output rather than being appended to it. Benefits in terms of flexibility, spectral containment, low latency, and robustness to Doppler spread and phase noise are discussed in the article.

Radio Resource Management Techniques for eMBB and mMTC Services in 5G Dense Small Cell Scenarios

Abstract: Research in 5G has so far been aimed towards laying out a conceptual vision and the engineering requirements. The focus is now shifting towards standardization through evaluation of potential solutions. 5G wireless communication system is expected to serve a diverse range of services with different design requirements. Dense small cells with multiple antenna nodes are believed to be key elements in meeting these challenging requirements. 5G will thus feature an adaptable air interface with carefully designed radio resource management techniques that can optimize each link according to its service requirements. This article provides an overview of key radio resource management techniques for 5G dense small cells and demonstrates how these techniques can contribute to fulfilling some of the important 5G requirements. Preliminary system level simulation results indicate that a mean throughput gain of around 63 %, and up to 84 % in latency reduction can be achieved utilizing the discussed resource management techniques.

On the impact of multi-user traffic dynamics on low latency communications

Abstract: In this paper we study the downlink latency performance in a multi-user cellular network. We use a flexible 5G radio frame structure, where the TTI size is configurable on a peruser basis according to their specific service requirements. Results show that at low system loads using a short TTI (e.g. 0.25 ms) is an attractive solution to achieve low latency communications (LLC). The main benefits come from the low transmission delay required to transmit the payloads. However, as the load increases, longer TTI configurations with lower relative control overhead (and therefore higher spectral efficiency) provide better performance as these better cope with the non-negligible queuing delay. The presented results allow to conclude that support for scheduling with different TTI sizes is important for LLC and should be included in the future 5G.

Enabling Early HARQ Feedback in 5G Networks

Abstract: Besides coping with the increasing demand of broadband services, 5th Generation (5G) radio access technology is expected to support mission critical communication (MCC) services targeting very low latencies. In this paper, we investigate the feasibility of the usage of an early Hybrid Automatic Repeat reQuest (HARQ) feedback for reducing the latency of acknowledged transmissions without disregaring spectral efficiency. As enabler of such early feedback, a new technique for predicting the decoder outcome before decoding occurs, is proposed. This technique is intended to generate an early ACK/NACK, or an uncertain feedback in case a reliable prediction cannot be achieved. Simulation results show a very limited occurrence of false positives and false negatives, and uncertain feedback rates not exceeding 6% when adaptive modulation and coding (AMC) and a 10% Block Error Rate (BLER) target is assumed. A correct early ACK/NACK can be generated for around 90% of the transmissions or more.

Sleep Modes for Enhanced Battery Life of 5G Mobile Terminals

Abstract: In addition to higher data rates and lower latency the 5G Radio Access Technology concepts are targeting to provide better battery life for mobile broadband and Machine Type Communication users. In this overview paper we analyze how microsleep, Discontinuous Reception and Transmission, and a wake-up receiver concept can be combined to enhance the battery life of 5G mobile terminals. Due to the short and pipelined 5G frame structure microsleep provides 20 % energy savings as compared to LTE. The Discontinuous Reception and Transmission modes also benefit from the new frame structure leading to faster connection setup and up to 80 % lower energy consumption depending on the traffic type. Finally we estimate that the wake-up receiver concept, when adapted to scheduled and cellular communication, can provide 90 % lower energy consumption and ensure a predictable and consistent latency.

An Empirical Study of Urban Macro Propagation at 10, 18 and 28 GHz

Abstract: This paper investigates the propagation characteristics of the urban macro cells at centimeter-wave (cmWave) frequencies, in particular at 10, 18 and 28 GHz The measurements are performed at several transmitter (Tx) locations and heights, in both line-of-sight (LOS) and non line-of-sight (NLOS) conditions, and with distances up to 1,400 m The distancedependent mean path loss and shadow fading standard deviation (std) are extracted for all cases based on a single-slope path loss model, and offered here for quick determination of link budget and system capacity The results show the potential usage of the cmWave band for mobile cellular services in the years to come: the NLOS path loss slopes at 10 and 18 GHz are not much different from the 2 GHz reference, and the corresponding offsets are in the order of 20-23 dB for 25 m Tx height This gap is expected to be overcome by the usage of high-gain miniaturized steerable antennas, which is feasible due to the reduced antenna aperture size at the cmWave band Similar to the 2 GHz band, the NLOS shadow fading std for cmWave is within 6 dB The effect of Tx height is clearly shown in the NLOS scenario: at 10 GHz, for example, 75 dB reduction in attenuation could be achieved by raising the Tx antenna from 15 m (below average roof-top) to 25 m (above roof-top), or 234 dB if the Tx height is elevated to 54 m

Ultra-reliable communication in a factory environment for 5G wireless networks: Link level and deployment study

Abstract: The focus of this paper on mission-critical communications in a 5G cellular communication system. Technologies to provide ultra-reliable communication, with 99.999 % availability in a factory environment are studied. We have analysed the feasibility requirements for ultra-reliable communication and obtained the loss margins against path loss, shadow and fast fading. We also study the effect of increased interference due to higher deployment density on offered reliable rates and packet delays. Resource allocation schemes based on full and orthogonal resource sharing, as well as power control are compared. Last, the importance of multi-hop communication and multi-point coordination schemes are highlighted to improve the reliable communication in presence of interference and clutter.

Can Full Duplex Boost Throughput and Delay of 5G Ultra-Dense Small Cell Networks?

Abstract: Given the recent advances in system and antenna design, practical implementation of full duplex (FD) communication is becoming increasingly feasible. In this paper, the potential of FD in enhancing the performance of 5th generation (5G) ultra-dense small cell networks is investigated. The goal is to understand whether FD is able to boost the system performance from a throughput and delay perspective. The impact of having symmetric and asymmetric finite buffer traffic is studied for two types of FD: when only the base station is FD capable, and when both the user equipment and base station are FD nodes. System level results indicate that there is a trade- off between multipleinput multiple-output (MIMO) spatial multiplexing and FD in achieving the optimal system performance. Moreover, results show that FD may be useful for asymmetric traffic applications where the lightly loaded link requires high level performance. In such cases, FD can provide an average improvement of up to 116% in session throughput and 77% in packet delay compared to conventional half duplex transmissions.

24 GHz cmwave radio propagation through vegetation: Suburban tree clutter attenuation

Abstract: This paper presents a measurement-based analysis of cm-wave radio propagation through vegetation at 24 GHz. A set of dedicated directional measurements were performed with horn antennas located close to street level inside a densely-vegetated area illuminated from above. The full azimuth was examined for the elevation range from +10 to +30 degrees at each of the measurement positions in order to explore the directional characteristics of the channel. The detailed analysis of the spatial multipath components scattered from the trees suggests, in average, the presence of 5 strong tree-scattered components per location with an azimuthal deviation of approximately 20 degrees between the strongest and the direct transmitter-receiver components. A diversity gain of approximately 7 dB is estimated, plus 2 dB extra in the case of considering multi-beam combining techniques. Tree clutter attenuation was found to be in the range 2.6–3.8 dB/m for the first meters inside the vegetated area. This attenuation can be predicted by the current ITU-R models, although some modifications are suggested. Single-tree attenuation was estimated to be approximately 20 dB. The different models and observations presented along the paper are useful for simulation and radio network planning of future wireless systems operating at 24 GHz in presence of vegetation.

On the performance of one stage massive random access protocols in 5G systems

Abstract: The next generation of cellular systems are expected to experience a proliferation of the number of emerging use cases alongside supporting high speed mobile broadband services. Massive Machine Type Communication (mMTC), which caters to a large number of low-data rate and low-cost devices, is such an use case. Smart utility meters, automated sensors in farms, and vehicle tracking nodes for logistics monitoring are all examples of emerging mMTC devices. Ensuring efficient mechanisms to access the wireless channel for such a massive number of densely deployed devices is the key challenge posed by mMTC applications. A framework for the analysis of the one-stage massive access protocol is proposed in this paper, which allows to model and evaluate its performance with respect to important performance metrics for mMTC services.

Analysing self interference cancellation in full duplex radios

Abstract: Full duplex communication promises a theoretical 100% throughput gain by doubling the number of simultaneous transmissions. Such compelling gains are conditioned on perfect cancellation of the self interference power resulting from simultaneous transmission and reception. Generally, self interference power is modelled as a noise-like constant level interference floor. However, experimental validations have shown that the self interference power is in practice a random variable depending on a number of factors such as the surrounding wireless environment and the degree of interference cancellation. In this study, we derive an analytical model for the residual self interference power, and demonstrate various applications of the derived model in analysing the performance of a Full Duplex radio. In general, full duplex communication is found to provide only modest throughput gains over half duplex communication in a dense network scenario with practical self interference cancellation models.

Analyzing the potential of full duplex in 5G ultra-dense small cell networks

Abstract: Full-duplex technology has become an attractive solution for future 5th generation (5G) systems for accommodating the exponentially growing mobile traffic demand. Full duplex allows a node to transmit and receive simultaneously in the same frequency band, thus, theoretically, doubling the system throughput over conventional half-duplex systems. A key limitation in building a feasible full-duplex node is the self-interference, i.e., the interference generated by the transmitted signal to the desired signal received on the same node. This constraint has been overcome given the recent advances in the self-interference cancellation technology. However, there are other limitations in achieving the theoretical full-duplex gain: residual self-interference, traffic constraints, and inter-cell and intra-cell interference. The contribution of this article is twofold. Firstly, achievable levels of self-interference cancellation are demonstrated using our own developed test bed. Secondly, a detailed evaluation of full-duplex communication in 5G ultra-dense small cell networks via system level simulations is provided. The results are presented in terms of throughput and delay. Two types of full duplex are studied: when both the station and the user equipments are full duplex capable and when only the base station is able to exploit simultaneous transmission and reception. The impact of the traffic profile and the inter-cell and intra-cell interferences is addressed, individually and jointly. Results show that the increased interference that simultaneous transmission and reception causes is one of the main limiting factors in achieving the promised full-duplex throughput gain, while large traffic asymmetries between downlink and uplink further compromise such gain.

On the benefits of early HARQ feedback with non-ideal prediction in 5G networks

Abstract: 5th Generation (5G) radio access technology aims at supporting services with different latency requirements in the same air interface. The usage of an early Hybrid Automatic Repeat reQuest (HARQ) feedback based on a prediction of the decoder's outcome allows reducing the over-the-air latency, with particular advantages for mission critical applications. However, predicting the ACK/NACK feedback before detection occurs is unfortunately error prone. In this paper, we discuss the potential of using an early HARQ feedback in 5G networks considering the occurrence of wrong predictions. Two options are studied: only the early feedback is transmitted, and both early and regular feedback are transmitted, with the possibility of the latter one of correcting wrong early predictions. Numerical analysis shows the potential of the early feedback of reducing the over-the-air latency up to 50%. Wrong estimates can, however, significantly affect outage rate and latency for the case of only early feedback, while their impact is very minor in case the regular feedback is empowered to correct them.

Measurement-based Evaluation of the Impact of Large Vehicle Shadowing on V2X Communications

Abstract: Upcoming applications, such as autonomous vehicles, will pose strict requirements on the vehicular networks. In order to provide these new services reliably, an accurate understanding of propagation in the vehicular scenarios is needed. In this context, this paper presents a measurementbased evaluation of large vehicle shadowing at 5.8 GHz in V2X scenarios. The receiver antenna height is fixed to average vehicular height (1.5 m), while the transmitter antennas are located at different heights (1.5, 5, and 7 m) in order to investigate both V2V and V2I scenarios. A truck was used to obstruct the LOS between transmitter and receiver, and a large number of geometrical combinations of the scenario were explored. The statistical analysis of the measurement shows how in the V2V case, the experienced shadow levels are approximately 5 dB higher than in the V2I scenarios, where the shadow levels depend on the transmitter antenna height, reaching maximum values of 21-23 dB. The statistical analysis also shows that the differences in shadow level due to the non-symmetries of the obstacle truck are in the order of approximately 2 dB. A simple 3D ray-tracing simulation is validated against the measurements, showing a good match with a RMSE of 4.1 dB. Based on both measurements and ray-tracing data, a simple deterministic shadowing model, useful for implementation in system level simulators, is presented, as a first step towards a more dynamic and scalable shadowing model.

The Coverage-Latency-Capacity Dilemma for TDD Wide Area Operation and Related 5G Solutions

Abstract: In this paper we present a novel configurable 5G time division duplex (TDD) frame structure, including a flexible scheduling (resource allocation) framework for wide area scenarios. The unavoidable tradeoffs between coverage, latency, and capacity are studied with the objective of deriving a 5G air interface solution that is capable of serving users with highly diverse service requirements. Among others, it is shown that coverage challenged users will experience larger latency, while other users can still be served with shorter latency if adopting the proposed 5G solution. Achieving low latency, does, however, come at cost of lower spectral efficiency, so our solution includes control mechanisms for determining on a per user basis if the link shall be optimized for latency or capacity.

On the potential of full duplex performance in 5G ultra-dense small cell networks

Abstract: Full duplex allows a device to transmit and receive simultaneously in the same frequency band, theoretically doubling the throughput compared to traditional half duplex systems. However, several limitations restrict the promised full duplex gain: non-ideal self-interference cancellation, increased inter-cell interference and traffic constraints. In this paper, we first study the self-interference cancellation capabilities by using a real demonstrator. Results show that achieving ∼110 dB of cancellation is already possible with the current available technology, thus providing the required level of isolation to build an operational full duplex node. Secondly, we investigate the inter-cell interference and traffic constraints impact on the full duplex performance in 5th generation systems. System level results show that both the traffic and the inter-cell interference can significantly reduce the potential gain of full duplex with respect to half duplex. However, for large traffic asymmetry, full duplex can boost the performance of the lightly loaded link.

Can full duplex reduce the discovery time in D2D communication

Abstract: Device-to-device (D2D) communication is considered as one of the key technologies to support new types of services, such as public safety and proximity-based applications. D2D communication requires a discovery phase, i.e., the node awareness procedure prior to the communication phase. Conventional half duplex transmission may not be sufficient to provide fast discovery and cope with the strict latency targets of future 5G services. On the other hand, in-band full duplex, by allowing simultaneous transmission and reception, may complete the discovery phase faster. In this paper, the potential of full duplex in providing fast discovery for the next 5th generation (5G) system supporting D2D communication is investigated. A design for such system is presented and evaluated via simulations, showing that full duplex can accelerate the discovery phase by supporting a higher transmission probability compared to half duplex. Simulation results show that, in order to meet the strict 5G control plane latency target, advanced receivers are required. In that case, full duplex can reduce the latency up to 80%.

Reference sequence design for zero-tail DFT-spread-OFDM

Abstract: Zero-tail Discrete Fourier Transform-spread OFDM (ZT DFT-s-OFDM) modulation replaces the Cyclic Prefix (CP) with a low power tail whose length can be dynamically configured to cope with the instantaneous delay spread of the channel. In this paper, we discuss the reference sequence design for ZT DFT-s-OFDM. Our proposed approach is based on a deliberate distortion of the known Zadoff-Chu (ZC) sequences aiming at adapting them to the ZT DFT-s-OFDM waveform while preserving their attractive properties. A numerical analysis confirms the validity of our design in generating ZT DFT-s-OFDM reference sequences with zero autocorrelation, limited cross-correlation, flat frequency response and low Peak-to-Average Power Ratio (PAPR).

Analysis and comparison of 24 GHz cmWave radio propagation in urban and suburban scenarios

Abstract: This paper presents a measurement-based comparison of cm-wave propagation in urban and suburban scenarios at 24 GHz with transmitter antennas located above rooftop level. Different sets of directional measurements, exploring the full azimuth and the range from −30 to +30 degrees in elevation, were performed with horn antennas located close to street level, in order to explore the spatial characteristics of the channel in both LOS and NLOS conditions. The statistical analysis of different directional indicators shows how, at 24 GHz, outdoor propagation is quite different in the suburban scenario as compared to the urban case. Increased spatial multipath, in average 1.23 times higher, is observed in the suburban scenario, mainly due to the strong presence of vegetation. This results in reduced suburban NLOS path loss exponents (3.4) in comparison to the urban scenario (3.7), as detailed in the outdoor path loss analysis. The paper also highlights the potential of using beam combining techniques in order to improve cell-edge coverage by 17% and 37% in the urban and suburban scenarios, respectively. Outdoor-to-indoor propagation was also investigated, finding an average penetration loss of 6.5 dB for buildings composed of light construction materials. The different results and observations provided in the paper are useful for modeling and simulation of future wireless networks operating at 24 GHz in urban and suburban scenarios.

Mission-critical mobile broadband communications in open-pit mines

Abstract: The need for continuous safety improvements and increased operational efficiency is driving the mining industry through a transition toward automated operations. From a communications perspective, this transition introduces a new set of high-bandwidth business-critical and mission- critical applications that need to be met by the wireless network. This article introduces fundamental concepts behind open-pit mining and discusses why this ever-changing environment and strict industrial reliability requirements pose unique challenges to traditional broadband network planning and optimization techniques. On the other hand, unlike unpredictable disaster scenarios, mining is a carefully planned activity. Taking advantage of this predictability element, we propose a framework that integrates mine and radio network planning so that continuous and automated adaptation of the radio network becomes possible. The potential benefits of this framework are evaluated by means of an illustrative example.

Verification of 3G and 4G received power measurements in a crowdsourcing Android app

Abstract: Many crowdsourcing Android applications are available for measuring network Key Performance Indicators such as received power, latency, and throughput. The data is useful for end-users, researchers, and Mobile Network Operators, but unfortunately the applications' accuracy are rarely verified. In this paper we verify the crowdsourcing Android application NetMap's ability to measure LTE Reference Signal Received Power by analyzing the Root Mean Squared Error, being 2–3 dB, and cross-correlation coefficient, being above 0.8, with measurements obtained by use of a professional radio network scanner and measurement phones. In addition, the application is applicable, but less accurate, for 3G Received Signal Code Power measurements. The studies are made for various device speeds and in different scenarios including indoor, urban, and highway, where the NetMap application is showed to perform well.

A novel channel estimator for Zero-Tail DFT-spread-OFDM

Abstract: Zero-tail Discrete Fourier Transform-spread-Orthogonal Frequency Division Multiplexing (ZT DFT-s-OFDM) waveform is considered as an attractive candidate for a 5th Generation (5G) radio access technology given its flexibility and spectral containment properties. However, high quality channel estimation in ZT DFT-s-OFDM is compromised by the necessity of accommodating a zero head/tail in the transmit signal. This zero-insertion affects negatively reference sequence properties such as cyclic zero-autocorrelation and flat frequency response. In this paper, we propose a novel channel estimator for ZT DFT-s-OFDM which circumvents such limitations by enabling the correlation of the received signal against the original sequence rather than its zero-padded version. Simulation results prove the benefits in terms of mean square error (MSE) of the proposed channel estimator with respect to existing solutions.

A Simple Statistical Signal Loss Model for Deep Underground Garage

Abstract: In this paper we address the channel modeling aspects for a deep-indoor scenario with extreme coverage conditions in terms of signal losses, namely underground garage areas. We provide an in- depth analysis with regard to the path loss (gain) and large-scale signal shadow fading, and propose a simple propagation model which can be used to predict cellular signal levels in similar deep- indoor scenarios. The measurement results indicate that the signal at 800 MHz band penetrates external concrete walls to reach the lower levels, while for 2000 MHz wall openings are required for the signal to propagate. It is also evident from the study that the shadow fading at different levels of an underground garage are highly correlated. The proposed frequency-independent floor attenuation factor (FAF) is shown to be in range of 5.2 dB per meter deep. Therefore, the attenuation rate in the z dimension is much higher than the in-building attenuation in x and y dimension, which is often assumed at 0.6 dB/m.

The Challenge of Wireless Connectivity to Support Intelligent Mines

Abstract: The need for continuous safety improvements and inc reased operational efficiency is driving the mining industry through a transition towards large-scale a utomation of operations, i.e., “intelligent mines”. The technology promises to remove human operators from harsh or dangerous conditions and increase productivity, from extraction all the way to the de liv ry of a processed product to the customer. In t his context, one of the key enablers is wireless connec tivity since it allows mining equipment to be remot ely monitored and controlled. Simply put, dependable wi reless connectivity is essential for unmanned mine operations. Although voice and narrowband data radi os have been used for years to support several type s of mining activities, such as fleet management (dispat ch) and telemetry, the use of automated equipment introduces a new set of connectivity requirements a d poses a set of challenges in terms of network pl anning, management and optimization. For example, the data rates required to support unmanned equipment, e.g. a teleoperated bulldozer, shift from a few kilobits/s econd to megabits/second due to live video feeds. T his traffic volume is well beyond the capabilities of P rofessional Mobile Radio narrowband systems and mandates the deployment of broadband systems. Furth ermore, the (data) traffic requirements of a mine a lso vary in time as the fleet expands. Additionally, w ireless networks are planned according to the chara teristics of the scenario in which they will be deployed, but mines change by definition on a daily-basis. There fore, a careful and continuous effort must be made to ensur e the wireless network keeps up with the topographi c and operational changes in order to provide the nec essary network availability, reliability, capacity and coverage needed to support a new mining paradigm. B y means of simulations, we analyze the effects on t he wireless network along 7 years of constant topograp hic changes in an open-pit mine coupled with much higher data requirements. The authors also present a new network topology that is able to partially me et the requirements posed by mining automation and discuss the consequences of not providing connectivity for all applications. The work also discusses how the c areful positioning of the heavy communications infrastructure (tall towers) from the early stages of the mine site project can make the provision of incremental capacity and coverage simpler.

Iterative normalization technique for reference sequence generation for zero-tail discrete fourier transform spread orthogonal frequency division multiplexing

Abstract: Systems, methods, apparatuses, and computer program products for generating sequences for zero-tail discrete fourier transform (DFT)-spread-orthogonal frequency division multiplexing (OFDM) (ZT DFT-s-OFDM) reference signals. One method includes adding a zero vector to an input sequence, and performing an iterative manipulation of the input sequence. The performing of the iterative manipulation of the input sequence may include, for example: computing frequency domain response of the sequence, normalizing elements of the computed frequency domain sequence to unitary power while maintaining phase of each of the elements, converting the sequence to time domain, generating a zero- padded sequence by forcing a zero head and tail of the sequence, and repeating the steps until a final sequence with zero-tail and flat frequency response is obtained.

Ultra-reliable communications in failure-prone realistic networks

Abstract: We investigate the potential of different diversity and interference management techniques to achieve the required downlink SINR outage probability for ultra-reliable communications. The evaluation is performed in a realistic network deployment based on site-specific data from a European capital. Micro and macroscopic diversity techniques are proved to be important enablers of ultra-reliable communications. Particularly, it is shown how a 4×4 MIMO scheme with three orders of macroscopic diversity can achieve the required SINR outage performance. Smaller gains are obtained from interference cancellation, since this technique does not increase the diversity order of the desired signal. In addition, failures or malfunction of the cellular infrastructure are analysed. Among different types of failures evaluated, results show that failures spanning over large geographical areas can have a significant negative performance impact when attempting to support high reliability use cases.

Impact of Transport Control Protocol on Full Duplex Performance in 5G Networks

Abstract: Full duplex (FD) communication has attracted the attention of the industry and the academia as an important feature in the design of the future 5th generation (5G) wireless communication system. Such technology allows a device to simultaneously transmit and receive in the same frequency band, with the potential of providing higher throughput and lower latency compared to traditional half duplex (HD) systems. In this paper, the interaction between Transport Control Protocol (TCP) and FD in 5G ultra- dense small cell networks is studied. TCP is a well- known transport layer protocol for providing reliability, which comes at the price of increased delay and reduced system throughput. FD is expected to accelerate the TCP congestion control mechanism and hence mitigate such consequences. System level results show that FD can outperform HD and alleviate the TCP drawbacks when the inter-cell interference is not the main limiting factor. On the other hand, under strong inter-cell interference, results show that the capabilities of the system to cope with such interference dictates the gain that FD may provide over HD.

A novel geometrical height gain model for line-of-sight urban micro cells below 6 GHz

Abstract: This paper presents a novel height gain model applicable to line-of-sight urban micro cell scenarios and frequencies below 6 GHz. The model is knife-edge diffraction-based, and it is founded on simple geometrical and physical relationships. Typical system level simulator scenario parameters are used as inputs to the model, where the only variable is outdoor-to-indoor penetration loss as it can vary depending on the external composition of the target building. The model is validated against two independently-obtained sets of measurements taken at different locations in China and Denmark. The model presents an average root-mean-square error accuracy of 6–7 dB, about 1–3 dB better than current existing models.