J. Wigard

• Nokia

In this tutorial we present recipes for dynamic systemlevel simulations (SLSs) of 5G and beyond cellular radio systems. A key ingredient for such SLSs is selection of proper models to make sure that the performance determining effects are properly reflected to ensure output of realistic radio performance results. We therefore present a significant...

Non-Terrestrial Networks (NTN) are expected to be part of 6G from the start of its use, with the main objective to provide ubiquitous global coverage, including indoor coverage. As NTN are being first introduced in a late phase of 5G, it is natural to use an evolution of 5G to 6G rather than a disruptive approach. In this article we describe the cu...

Cellular-connected unmanned aerial vehicle (UAV) has attracted a surge of research interest in both academia and industry. To support aerial user equipment (UEs) in the existing cellular networks, one promising approach is to assign a portion of the system bandwidth exclusively to the UAV-UEs. This is especially favorable for use cases where a larg...

Low-Earth orbit (LEO) satellite networks are meant to be fundamental to closing the digital divide, enabling new market opportunities and providing fifth-generation (5G) New Radio (NR) connectivity everywhere at any time. Despite the advantages of LEO deployments, these systems are characterized by a high mobility and a challenging propagation chan...

An accurate estimation of the service quality that the user will experience along a route can be extremely useful for mission-critical services. It can provide the network with in-advance information on the potential critical areas along the route based on availability and reliability estimations. If such estimation is based on empirical/statistica...

Cellular connected unmanned aerial vehicle (UAV) has been identified as a promising paradigm and attracted a surge of research interest recently. Although the nearly line-of-sight (LoS) channels are favorable to receive higher powers, UAV can in turn cause severe interference to each other and to any other users in the same frequency band. In this...

Power control is becoming increasingly essential for the fifth-generation (5G) and beyond systems. An example use-case, among others, is the unmanned-aerial-vehicle (UAV) communications where the nearly line-of-sight (LoS) radio channels may result in very low signal-to-interference-plus-noise ratios (SINRs). Investigations in [1] proposed to effic...

Cellular-connected unmanned aerial vehicles (UAVs) have recently attracted a surge of interest in both academia and industry. Understanding the air-to-ground (A2G) propagation channels is essential to enable reliable and/or high-throughput communications for UAVs and protect the ground user equipments (UEs). In this contribution, a recently conduct...

This chapter explains that existing long‐term evolution networks and future 5G networks are able to ensure reliable command and control (C2) communication to drones and play an important role in the provisioning of end‐to‐end reliability for drone communications, similar to other use cases requiring high reliability. In unmanned aerial vehicles (UA...

Cellular-connected unmanned aerial vehicles (UAVs) have recently attracted a surge of interests in both academia and industry. Understanding the air-to-ground (A2G) propagation channels is essential to enable reliable and/or high-throughput communications for UAVs and protect the ground user equipments (UEs). In this contribution, a recently conduc...

Interference management through power control is essential to optimize the system capacity. With the introduction of aerial user equipments in cellular networks, resulting in an increase of line of sight links, power control is becoming more and more vital to enable the (uplink) high-throughput data streaming and protect the users on the ground. Th...

High-throughput unmanned aerial vehicle (UAV) communication may unleash the true potential of novel applications for aerial vehicles but also represents a threat for cellular networks due to the high levels of generated interference. In this article, we investigate how a beamforming system installed on board a UAV can be efficiently used to ensure...

Due to safety concerns, a reliable radio communication link is a key component in the future application of unmanned aerial vehicles (UAVs), as it will enable beyond visual line-of-sight (BVLOS) operations. In terms of cost and deployment time, radio communication for aerial vehicles will greatly benefit from the ready-to-market infrastructure and...

Aerial users, such as unmanned aerial vehicles (UAVs), experience different radio propagation conditions than users on the ground. This is a concern regarding the integration of such users in the cellular networks in the near future. This paper investigates the impact of uplink transmissions from an aerial user equipment. Full buffer transmissions...

Widely deployed cellular networks are an attractive solution to provide large scale radio connectivity to unmanned aerial vehicles. One main prerequisite is that co-existence and optimal performance for both aerial and terrestrial users can be provided. Today’s cellular networks are, however, not designed for aerial coverage, and deployments are pr...

The main goal of this paper is to obtain models for path loss exponents and shadowing for the radio channel between airborne Unmanned Aerial Vehicles (UAVs) and cellular networks. In this pursuit, field measurements were conducted in live LTE networks at the 800 MHz frequency band, using a commercial UAV. Our results show that path loss exponent de...

The objective of this paper is to propose traffic steering solutions that aim at optimizing the end-user throughput. Two different implementations of an active mode throughput-based traffic steering algorithm for Heterogeneous Networks (HetNet) are introduced. One that always forces handover of the active users towards the cell offering the highest...

This chapter presents HSPA multicarrier and Multi-antenna Multiple Input Multiple Output (MIMO) capabilities introduced in Releases 7 onwards all the way to the on-going Release 12 work on uplink enhancements involving uplink multicarrier operation. This chapter first covers the multicarrier operation first introduced with dual-carrier HSDPA downli...

In this paper, evaluation of HSPA radio technology is provided with the reference to IMT-Advanced requirements. Recent technological advancements are included to verify if HSPA is capable of meeting these requirements. Extensive system-level simulation campaigns are carried out, which shadow IMT-A performance evaluation guidelines and suggested tes...

Mobility Robustness OptimisationMobility Load Balancing and Traffic SteeringEnergy SavingCoverage and Capacity OptimisationRACH OptimisationRRM and SON (Interference Coordination, P0 Optimisation)References

In this paper traffic steering between a High- Speed Downlink Packet Access (HSDPA) network and a 3GPP Long Term Evolution (LTE) network with different carrier frequencies is investigated. First, two traffic steering algorithms, relying on static network information, are assessed from a traffic theoretical point of view and numerically. Furthermore...

Small cells are popular deployment options for coverage holes and capacity hotspot areas. Due to the poor outdoor-to-indoor propagation property of in-building environment, a dedicated wireless system installed inside the building is often preferred for providing indoor users high- data-rate services. Distributed antenna systems and Femto cells are...

In the Long Term Evolution system Discontinuous Transmission and Reception (DRX/DTX) has been introduced to extend the terminal battery lifetime. In this paper, we study the energy-saving provided by this mechanism and the impact on the QoS performance of Voice over IP (VoIP) traffic under dynamic and semi persistent packet scheduling strategies. S...

This paper focuses on the Physical Downlink Control Channel (PDCCH) and describes the impact of its realistic constraints on the performance in E-UTRAN LTE TDD system, particularly considering the asymmetric slot resources between downlink and uplink. It is described, when adopting the same PDCCH manager framework in LTE FDD system as in LTE FDD sy...

This paper studies the different ways of extending wireless coverage for high data rates and improving the data capacity in a building. The solutions considered include deployments of single or multiple small base stations, i.e. Picocell or Femtocell, and distributed antenna system, operated on the same frequency as the macro cellular network. We l...

This paper deals with packet scheduling for Voiceover-IP (VoIP) traffic in the Long Term Evolution (LTE) EUTRAN Downlink. The more specific target is to optimize the performance of dynamic scheduling for traffic mixes of VoIP and best effort users. To this end, we introduce the Required Activity Detection (RAD) packet scheduling algorithm with Dela...

For the future LTE-Advanced network, one of the requirements in the uplink (UL) direction is to enhance the celledge user performances. Coordinated multi-point reception in the UL is one of the techniques being investigated to further improve the performance of LTE networks. With the help of the information coordination through the links between th...

In LTE Uplink, the slow varying pathgain and shadowing are compensated by the standardized open loop power control (OLPC) which is based on a power density offset and a compensating factor for the pathloss experienced by the users. The optimization of those parameters reveals a dependency on the allocated bandwidth. A Load Adaptive Power Control (L...

This paper focuses on the Physical Downlink Control Channel (PDCCH) and describes the impact of its realistic constraints. Specifically, the impact on the performance of the UTRAN LTE FDD downlink and on the QoS provisioning is studied. It is described, when adopting a QoS-aware packet scheduling policy, how scheduling limitations due to control ch...

In the UTRAN long term evolution (LTE), the downlink data channel is shared among the active users through the orthogonal frequency division multiple access (OFDMA) technique, and high gains can be achieved by using dynamic packet scheduling. Control channels introduce an additional overhead, but also play a key role in exploiting such gains. This...

The UTRAN long-term evolution (LTE) specifications provide flexible means to achieve micro-sleep operation for user equipment (UE) even though it is in active mode and running a service. By means of a discontinuous reception (DRX) framework, pauses in the transmission due to natural traffic characteristics or network prioritization can be utilized....

Antenna tilt is an effective inter-cell interference reduction technique which has been studied a lot previously in the CDMA-based systems. In this paper, we concentrate on the evaluations of the mechanical antenna downtilt in the uplink LTE networks. The SINR performance and the trade-off between the cell coverage and capacity are studied in a hom...

In LTE uplink, the slow varying path gain and shadowing are compensated by the standardized open loop power control (OLPC). Further optimization of the system performance can be done via closed loop power control commands. In this contribution, it is shown that using such commands to control the interference caused by users to the system, it is pos...

The UTRAN long-term evolution (LTE) provides flexible means to achieve micro-sleep operation for user equipment (UE) even though it is in active mode and running a service. By means of a discontinuous reception (DRX) framework pauses in transmission due to natural traffic characteristics or network prioritization can be utilized. However, the optim...

The 3GPP UTRAN Long Term Evolution (LTE) system utilizes packet based architecture with distributed mobility management, where the E-UTRANNode-B (eNB) takes the responsibility of making the hard handover/handoff (HO) decisions based on the user equipment (UE) measurements. To cope with the corner effect due to the loss of the line of sight (LOS), a...

This paper illustrates the optimization of design parameters for quality-of-service (QoS) aware packet schedulers in multi-service environments with WCDMA/HSDPA. The optimization sets the objective of maximizing the cell throughput while meeting certain minimum QoS criteria and focuses on two variants of the proportional fair with barrier function...

To minimize the terminal's transmission power in bursty uplink traffic conditions, the evolved high-speed uplink packet access (HSUPA) concept in 3GPP WCDMA includes a feature known as dedicated physical control channel (DPCCH) gating. We present here a detailed link level study of gating from a link efficiency (LE) perspective; LE being expressed...

Transmission Control Protocol (TCP) Round Trip Time User-specific Packet Scheduling Cell-specific Packet Scheduling Packet Data System Performance Packet Data Application Performance References

The E-HICH is a downlink control channel associated to the HARQ procedure in HSUPA. It allows the MAC-e entity in the NodeB to signal the correct or incorrect reception of a given MAC-e PDU by transmitting ACKs or NACKs. Errors on this channel can cause misinterpretations and impact the overall system performance. This paper looks at the performanc...

The relative contribution of the transport network towards the per-user capacity in mobile telecommunication systems is becoming very important due to the ever increasing air-interface data rates. Thus, resource management procedures such as admission, load and handover control can make use of information regarding the available bandwidth in the tr...

This paper presents HSDPA performance evaluation in an urban micro cell environment with outdoor base station antenna heights below roof-top level (10 m) and both outdoor and indoor pedestrian mobiles (3 km/h). A path loss model which accounts for the 3D geometry of the radio environment is used, thus allowing the simulation of indoor user location...

For the WCDMA/HSUPA concept, a key to ensuring high spectral efficiency is to correctly adjust the transmission power ratios among the data and control channels. This paper provides optimal values for the power ratio between the enhanced-dedicated physical data channel (E-DPDCH) and the dedicated physical control channel (DPCCH) from a Link Efficie...

Quality of Service in mobile telecommunication systems is usually identified by some basic performance metrics such as delay, throughput and jitter. However, the main impact of service quality is on the end user, and as such a detailed study of service performance should involve the end user. In this paper, such an approach is taken where subjectiv...

High speed uplink packet access (HSUPA) improves the cell throughput by faster scheduling, L1 HARQ and enhanced bit rates. This paper introduces a dynamic system simulator for studying HSUPA system performance. This simulator is used to analyze the effect on the cell throughput of increasing the BLER target and the target number of transmissions. T...

General performance factorsSingle-user performanceCell capacityHSUPA performance enhancementsConclusions Bibliography

The evaluation and optimization of packet service performance in wireless networks is a complex process, considering the number of heterogeneous entities and protocols that are involved. An emulation platform comes at hand for such performance investigations as it provides a means to see the performance from an end-2-end (E2E), user-perceived Quali...

The Radio Link Control (RLC) protocol of Universal Mobile Telecommunication System (UMTS) provides link layer reliability that could mitigate the effects of the hostile radio propagation channel on packet data transmission. In this paper, the impact of some of the RLC reliability mechanisms on the performance of File Transport Protocol (FTP) is inv...

This chapter presents the radio access algorithms for supporting packet switched services and analyses their performance. Such services are, for example, messaging, email, WAP/web browsing, streaming video or Voice over IP. The chapter discusses the Packet data protocols. It analyses the network delay aspects in terms of round trip time. The chapte...

This paper addresses the performance gain of interference cancellation (IC) and 4-branch antenna diversity for enhanced packet data access in WCDMA uplink. A theoretical analysis is derived showing that the cell throughput gain from IC mainly depends on three factors: 1) the efficiency of the multi-user detection (MUD) receiver, 2) the other-to-own...

This paper contains an evaluation of three different time and code division schedulers, for data transmission on enhanced dedicated channel (E-DCH) in WCDMA uplink. Time scheduling on E-DCH is possible thanks to fast node B scheduling operation on a transmission time interval (TTI) basis. Time scheduling allows for allocating users for transmission...

The present paper analyzes the paradigm of providing streaming services over HSDPA. The provision of QoS to streaming users imposes two major challenges on the HSDPA technology, namely, satisfying the guaranteed bit rate and delay jitter constraints. Focusing on the latter QoS requirement, the operation of the packet scheduling functionality comple...

The present paper focuses on assessing the performance of the packet scheduler in HSDPA. The investigation has especially concentrated on assessing different scheduling methods with different degrees of fairness for non-delay-sensitive elastic traffic. The fairness ultimately determines the QoS perceived by the users. The results show that very unf...

The performance of WCDMA uplink systems deploying Node B based scheduling and fast hybrid ARQ (HARQ) retransmission protocols is studied. With fast Node B scheduling and fast L1 HARQ schemes, both the uplink packet scheduling functionality and the entity controlling the retransmission mechanism are moved from the radio network controller (RNC) to t...

GSM Radio System DescriptionCellular Network Key Performance Indicators (KPIs)Spectral EfficiencyEFL Trial MethodologyBaseline Network PerformanceReferences

Basic GSM PerformanceReuse PartitioningTrunking Gain FunctionalityPerformance of GSM HR Speech ChannelsAdaptive Multi-rate (AMR)Source AdaptationRel'5 EDGE AMR EnhancementsSingle Antenna Interference Cancellation (SAIC)Flexible Layer OneReferences

In this paper, we study the operation of release'99 packet scheduler of the UMTS system. We focus on the uplink direction of data transmission. The aim is to investigate the performance of the packet scheduler data scheduling on dedicated transport channels. We emphasize in particular a power based packet scheduler (PS) with fair resource sharing....

This article focuses on the Quality of Service (QoS) achieved by packet scheduling. A packet scheduling algorithm, which can differentiate the QoS among user and service classes, is presented. The algorithm can be tuned from signal to interference ratio (C/I) based scheduling to Round Robin and beyond. Thus, an operator can choose between optimizin...

The present paper highlights the performance of the transport control protocol over WCDMA networks. The TCP flow control adjusts the transmission rate to the network and receiver's capacity. Due to this protocol self-adaptation to the transmission conditions of the links involved in the TCP connection, the protocol performance can not be disconnect...

Energy transmitted per correct received bit is used as cost function for evaluating the radio resource consumption of each user within a UMTS network, according to the requested quality of service (QoS) class. Diverse packet scheduler algorithms are analysed, determining their impact on packet delay, throughput and packet call delay. Results show t...

Networks with different reuses, with and without DTX are compared by using the effective frequency load concept (EFL). EFL makes it possible to compare networks under different circumstances, like for example different weekdays or networks using different configurations. The simulations results show that networks using high frequency reuse factors...

In GPRS four coding schemes have been defined with different degrees of data protection. The selection of a fixed one for a certain packet transmission would lead to a throughput loss if the channel quality conditions vary during the connection, therefore, a link adaptation algorithm based on a block error rate (BLER) estimation is proposed and ana...

Discontinuous transmission (DTX) is a feature which has been reported to give about 2.5 dB gain in C/I performance. However in real life, network operators, who switch on DTX, often experience a loss in performance. They measure the performance by the RXQUAL distribution. RXQUAL is a quality parameter used in GSM, which is directly related to the e...

Traffic reason handover is a functionality that distributes the traffic out over the network according to the traffic load. This can decrease the blocking and thus increase the quality of service (QoS). Its potential gain is analytically calculated and network simulations are performed to evaluate the performance. It is shown that the capacity gain...

Resource allocation in a frequency hopping network is even more problematic than in a traditional network. The combined effect from all serving frequencies has to be considered directly in the allocation process. An algorithm doing this for a PCS1900/GSM/DCS1800 type of network is presented. The frequency as well as the interference diversity gain...

Baseband frequency hopping in the combination with downlink power control and discontinuous transmission has been investigated as a quality improving feature in a live GSM network. Using the dropped call rate and the frame erasure rate to measure the network quality, the use of frequency hopping proves a powerful network quality enhancement feature...

Performance analysis of a mobile communications system is often done separately at network and at link level. It is difficult to study a modern mobile communications system like GSM analytically, due to the complexity. Hence simulations are used. It is desirable to include all link aspects in a network simulator, but without having to simulate ever...

Slow frequency hopping is a quality and capacity enhancement feature for the GSM system. However, in order to achieve a significant gain from frequency hopping, it has been shown that at least 3 to 4 frequencies are required in the hopping sequence. In band-limited networks that many frequencies per cell are not always available. Two network featur...

IUO (intelligent underlay-overlay) in a combination with random frequency hopping in GSM is analysed. Several improvements to the original IUO concept analysed in Nielsen et al. (1997) are introduced. With the improved IUO concept it is possible to load a network configuration consisting of 4 regular frequency channels and 3 super layer channels al...