Wireless technologies | Background Big data and the Internet of Things How the mobile ­communications industry is meeting the challenge

8 Projects of the future such as the Internet of Things, enhanced mobile broadband and self‑driving cars require extreme mobile network performance. 5G, the next generation of mobile communications, is expected to deliver the necessary performance. But thanks to continual technological enhancements, in particular LTE / LTE-Advanced networks provide an excellent evolution path. Here an overview.

If we take the 1990 specifications freeze significant improvements. The theoreti- Introducing LTE / LTE‑A has allowed for the 900 MHz GSM standard as zero cally achievable data rate per device has network operators to meet increasing hour, digital wireless ­communications evolved from a few 100 kbit/s (EDGE) to demands. The success of this technol- has just celebrated its 25th birthday. 42 Mbit/s (HSPA+) to several hundred ogy can also be seen in the fact that There is, however, no sign of ­slowing Mbit/s (LTE / LTE‑A). State‑of‑the‑art, 442 commercial networks have been down – far from it in fact. The ­hunger commercially available LTE‑A devices implemented in 147 countries around for data in cellular communications achieve 600 Mbit/s in ideal lab envi- the world since the first commercial remains insatiable and the demand for ronments. In a real network, propaga- LTE network was launched in late 2009 further technological progress persists. tion conditions and the shared channel (source: Global Mobile Suppliers Asso- A tenfold increase in mobile data traffic principle reduce achievable download ciation (GSA), October 2015). The fol- is expected over the next six years, and speeds due to the fact that available lowing section explores several key LTE experts predict an exponential increase bandwidth is divided among all active improvements resulting from enhance- in the number of things (Internet of subscribers. Nonetheless, LTE / LTE‑A ments introduced by the 3GPP stan- Things, IoT) that communicate with technology has significantly enhanced dardization body (as of Release 10, LTE each other via mobile networks. The available data rates and network capac- is also referred to as LTE‑Advanced Ericsson Mobility Report reports 87 mil- ity. The following innovations have been or LTE‑A). lion new mobile subscribers in the third essential to this achievement: quarter of 2015 alone (with 13 million ❙❙A wide system bandwidth of 20 MHz LTE features a specific enhanced mul- in India, 24 million in Africa and 7 mil- that can be provided to an individual timedia broadcast multicast service lion in China). Mobile subscriptions are subscriber as well as the ability to bun- (eMBMS, see NEWS 213, p. 10) that forecast to reach 9.1 billion by late 2021. dle up to five of these 20 MHz car- makes it possible to allocate the same In 2015, the average smartphone user rier frequencies for each subscriber resources (frequency and time) to mul- consumed 1.4 Gbyte of data monthly. (commonly known as carrier aggre- tiple subscribers within a cell. This is This is expected to rise to 8.5 Gbyte by gation, CA). CA is the most significant a highly efficient method of address- 2021. The combination of these two fac- improvement within LTE-Advanced in ing mobile TV applications, for exam- tors will result in exponential data traffic 3GPP Release 10. ple, where many subscribers receive the growth around the world. ❙❙Use of spatial multiplexing (MIMO same data simultaneously. This mode technology), i. e. using anywhere from also allows wireless devices to install This article describes how immense data two to eight/four transmit/receive new software efficiently – a task that volumes are being transmitted today antennas. generally still takes place via individual and how mobile network operators are ❙❙Fast OFDMA multiplexing, i. e. the fre- data connections for each device. ensuring that they can offer their sub- quency and time resource allocation scribers an excellent quality of experi- can be changed on a millisecond basis. Since WLAN is implemented in almost ence in the future. The smallest resource that can be allo- all wireless devices, WLAN connec- cated to a wireless device is a resource tions are available in private homes and block (RB) with a frequency of 180 kHz in many public locations. Many mobile 2G / 3G / 4G technologies and a time duration of 0.5 ms. network operators set up hotspots in and future improvements ❙❙High‑quality modulation methods, spe- exposed areas such as airports to pro- Looking at the different 2G (GSM, GPRS, cifically QPSK, 16QAM, 64QAM and vide an alternative means of access- EDGE), 3G (UMTS, HSPA, HSPA+) and 256QAM. ing the Internet. The user of the wire- 4G (LTE / LTE-Advanced (LTE‑A)) mobile less device can simply turn the WLAN technologies, it becomes clear that the A lean network architecture and function off and on to gain access. introduction of new transmission meth- pure packet-switched data transmis- Some wireless devices also feature a ods on the air interface between base sion enable short network response dedicated application that automati- stations and wireless devices as well times. LTE smartphones load Inter- cally switches the device’s data con- as the optimization of the mobile net- net pages much faster than with older nection to WLAN as soon as it detects work architecture have resulted in technologies. a hotspot with sufficient performance.

NEWS 214/16 9 Wireless technologies | Background

In such cases, all data traffic is routed is available. Therefore, 3GPP pro- (CoMP) was introduced to counteract either via the mobile network or WLAN. vides complementary solutions using this effect. CoMP makes it possible to In the 3GPP specifications, a special WLAN and LTE technology. Commer- transmit a signal to a wireless device at mode is available to use, for ­example, cial deployments will decide whether the cell boundary in a coordinated man- an email application running in the and which of these solutions will be ner. There are various ways of imple- background via WLAN while transmit- adopted. menting this coordination. In the sim- ting video data via LTE. However this plest case, it is merely decided which has not (yet) been adopted in commer- LTE networks use the same frequency of the potentially available base stations cial networks. Generally, network oper- in every cell, which leads to intercell is to be used for transmission. Other ators gain considerably more flexibil- interference at cell boundaries. A wire- options include allocating resource ity when using WLAN and LTE and can less device with an active ­connection blocks for wireless devices or directing provide their subscribers with higher to a base station receives the ­signals the antenna beams of the base stations data rates and more capacity. As an of the neighboring cell’s base station, involved to minimize interference. Using alternative, operating LTE / LTE-A in unli- which is sending signals to its con- MIMO technology and also influenc- censed frequency bands is soon to be nected devices. This causes interference ing the baseband signal (precoding) in a enabled from a specification perspec- and lowers achievable data rates, an coordinated manner allows optimal cov- tive (licensed-assisted access, LAA) and effect that especially impacts heteroge- erage at cell boundaries. An additional to be included in the upcoming 3GPP neous network environments, i. e. net- technology component named dual Release 13 in March 2016. Instead of work topologies in which multiple small connectivity has been specified in 3GPP switching from LTE to WLAN, LTE is (femto or pico) cells are operated within Release 12 to offer further improve- used, for example, in the unlicensed a large (macro) cell. Pedestrian zones ment for heterogeneous networks. The 2.4 GHz ISM band and the data rate are a good example. Small, high‑capac- wireless device is configured for con- capability is increased using the carrier ity hotspots cover high-traffic areas, yet nection to two base stations on two dif- aggregation feature. A listen-before-talk they may also be within the receive ferent carrier frequencies. The mas- function is added to LTE to avoid con- range of a higher‑level cell that cov- ter base station (eNodeB in LTE) sup- flicts and ensure that access to bands ers parts of the city. Coordinated mul- plies the higher‑level macro cell, and is granted only when sufficient capacity tipoint transmission and reception the slave eNodeB supplies the hotspot,

How does T&M equipment contribute? Test and measurement equipment plays a central role in both introducing new technologies and in operating networks. Countless test solutions are required to develop and manufac- ture mobile devices, components, base stations and switch- ing nodes. Test solutions are also needed when deploying the network and verifying its performance.

First, network operators have to select the right infrastruc- ture products to operate their networks. Using instruments such as signal generators and signal and spectrum analyz- ers, they can qualify infrastructure products in order to select those that perform best. The Global Certification Forum (GCF) defines a broad range of tests as a prerequisite for wireless device certification. Many operators specify additional tests based on their specific network requirements. T&M equip- ment such as the R&S®CMW500 wideband radio communi- cation tester emulates all required network functions and veri- Fig. 1: RF and protocol testing systems help network operators select suit- fies whether a wireless device is behaving properly (functional able wireless device providers. The test solutions ensure that the devices test of implemented protocols) and whether the hardware comply with mobile network standards.

10 i. e. a pico or femto cell. In this configu- The introduction of device‑to‑device to public safety and security applica- ration, the master eNodeB uses param- (D2D) capabilities is of special impor- tions. Initially, use by the general pub- eters such as cell traffic and device tance, as these provide two fundamen- lic will be confined to application‑related speed to decide to use the macro cell tal new functions. First, the network- broadcast services. Other ­commercial or the hotspot for the data connection. supported discovery function makes it usage models are conceivable and are Switching between the two is extremely possible for two spatially neighboring also under discussion as part of the fast and requires no additional signal- wireless devices to detect each other. 5G development process. In particu- ing. This saves signaling capacity and Second, these devices and others in lar automotive use cases are applica- minimizes handover errors. In wire- their vicinity will be able to exchange ble, i. e. potentially supporting autono- less devices, interference at cell bound- data directly, i.e. without going through mous driving. aries can be countered by employing the base station covering the area. improved receivers that recognize these However at least for the in-coverage Even though LTE / LTE‑A networks are specific types of interference and use case, i. e. if at least one device is located increasing in performance, comprehen- appropriate algorithms to remove them within cellular coverage, the whole pro- sive 4G coverage will take time. Effi- from the received signal. Additional cess is authenticated and configured cient handover to 2G and 3G technol- information about potential interference by the network. The introduction of this ogies remains critical. There are also can also be provided by the network to completely new functionality was pri- many use cases where low data rates improve such calculations. In the LTE marily motivated by public safety con- are sufficient. Here, the focus is on standard, these technology compo- siderations. Fire‑service and police cost-efficient solutions with long bat- nents are called further enhanced inter- applications need to exchange large tery life. In such machine‑to‑machine cell interference coordination (feICIC, amounts of data (images, videos) within (M2M) environments, modules with included in 3GPP Release 11) and net- small groups of individuals, some of e. g. GPRS technology designed to last work assisted interference cancellation whom may be located outside network years are often used. However, LTE / and suppression (NAICS, included in coverage areas, e. g. in the basement LTE‑A has already ushered in several 3GPP Release 12). of a burning building. Exchanging data improvements to serve M2M applica- between wireless devices connected tions. For example, there is a category 0 in this manner will initially be limited for LTE user equipment that reduces the

is correctly implemented (e.g. it complies with the speci- fied maximum transmit power). Fig. 1 shows suitable confor- mance test systems, such as the R&S®TS8980.

When deploying base stations in the field, compact testers are needed that can be used to quickly verify whether regu- latory requirements are being met (Fig. 2). Following deploy- ment, operators need to adjust parameters, such as hand­over thresholds, and identify coverage gaps in order to optimize their network and ensure the best possible data rates. Fig. 3 shows a drive test solution for effective mobile network plan- ning. QualiPoc from SwissQual implements a measurement application on a commercial smartphone. The test solution can be used like a normal app, enabling network operators to evaluate end user experience. In the operator’s core network, where all data streams are processed, it is increasingly impor- tant to be able to analyze data traffic down to the packet level. This makes it possible to classify the data traffic and optimally route a service’s data packets through the network. IP anal- Fig. 2: Cost‑efficient mobile T&M equipment is used to install a ysis technology from Rohde & Schwarz subsidiary ipoque base station.

NEWS 214/16 11 Wireless technologies | Background

effort required to implement this class with all of their enhancements will not Research institutes and development of devices (lower data rate requirements be able to cover the demand in the departments in major wireless commu- and no MIMO support). Processes have long term. Second, the definition of a nications companies are already con- also been introduced to prevent mobile new industry-wide use case class to ducting extensive studies in the field network overloading when large num- significantly improve mobile network of 5G technology. These efforts are pri- bers of M2M devices attempt to access latency. These use cases will at least marily dedicated to four technology the network at the same time. Other partly require extremely secure and reli- blocks, which are being discussed as enhancements, such as a reduced able connections. It will then be possi- the solution for future requirements. Ini- bandwidth (200 kHz) and even a reduc- ble to use cellular communications in tial research efforts will identify which tion of the subcarrier offset from 15 kHz the automotive industry (e. g. support- additional frequency bands can be to 3.75 kHz, are currently discussed in ing autonomous driving) and in Indus- made available by substantially increas- 3GPP standardization (Release 13). try 4.0 applications, opening up new ing the bandwidth. This research cov- sources of revenue. Latency require- ers the spectrum up to 100 GHz with In summary, for the time being LTE / ments in the 1 ms range are impossible bandwidths up to 2 GHz. Here, the sig- LTE‑A technology covers the increas- to implement with LTE/LTE‑A. In addi- nificantly changed channel propagation ing requirements of mobile data traffic tion to technology‑based arguments, conditions play a key role. Researchers as well as M2M / IoT. Enhanced mobile the previous development cycle indi- must analyze these conditions before broadband and IoT are also major cates that the next technological step they can develop and evaluate appropri- aspects of the comprehensive dis- will take place in 2020. GSM was intro- ate channel models to assess new tech- cussion taking place on the next gen- duced in 1990, UMTS in 2000 and LTE nologies (the next article shows how to eration (5G). What is motivating the in 2010. By the way, it should be men- analyze potential channels). The use of industry to introduce a new genera- tioned that the 2020 Olympic Games large numbers of transmit and receive tion of mobile communications as early will be hosted by Japan – a country that antenna elements (order of ­magnitude: as 2020 (or even 2018 on a regional is heavily involved in the development 100) is also under evaluation. They can basis)? First, due to the constantly of 5G (naturally not only for this reason). be used to increase data rates in the fre- increasing number of subscribers and quency spectrum below 6 GHz through data rates, even LTE / LTE‑Advanced advanced MIMO techniques. In the

provides this insight. The same functionality is also of great interest for mobile device testing. When implemented on the R&S®CMW500, users can analyze which IP data streams (including protocols used) a smartphone maintains only due to applications running in the background.

There can always be unforeseen interference when operating­ mobile networks. Stationary network monitoring tools in the mobile network and mobile interference hunting solutions are used to identify and eliminate this interference as quickly as possible. For example, malfunctioning neon signs can create interference in a base station’s receive band and ­negatively impact all data traffic in a cell. Fig. 4 shows a technician using a mobile measuring receiver and a directional antenna to locate interference sources.

Fig. 3: Network operators use T&M equipment to analyze network perfor- mance and optimize the end user experience.

12 high frequency range, they are nec- operators to move these functions to new demands stemming from vertical essary to provide the antenna gain alternative platforms in the case of a branches of industry (automotive indus- required to achieve appropriate cell hardware failure. Ultimately, the pro- try, health care, robot control, etc.) are sizes. New air interface technologies are cesses will be similar to those already expected to dictate a need for further being discussed in connection with sig- in place in data centers today. Network significant enhancements. That is why nificantly higher frequencies and as a function virtualization (NFV) and soft- researchers in the mobile communica- way to enable extremely short reaction ware defined networking (SDN) as well tions industry are already discussing 5G times. Some of these interfaces have as network slicing are helping drive the as they look toward 2020 and beyond. additional filter functions based on the flexible implementation of these func- Rohde & Schwarz and its subsidiaries OFDM technology implemented in LTE. tions in mobile networks. It should be SwissQual and ipoque offer a compre- Examples include universal filtered mul- noted that security aspects are exten- hensive portfolio for today’s T&M tasks ticarrier (UFMC), filter bank multicarrier sively discussed in this context. and are actively involved in 5G research (FBMC), generalized frequency division and development. multiplexing (GFDM) and filtered (some- Meik Kottkamp times called flexible) OFDM (f-OFDM). Summary A more efficient network topology is The high performance of LTE / LTE-A also being looked into, a topology that technology, its seamless cooperation is already starting to be used today. The with existing 2G / 3G networks and the fundamental idea is to design software complementary use of WLAN enable functions that are specific to mobile network operators to meet their sub- communications and to implement scribers’ continuously growing big them on open hardware platforms. This data requirements. Broadcast / multi- would make it possible to more afford- cast solutions enhance system flexibil- ably implement enhanced packet core ity. M2M applications are already play- (EPC) node functions in mobile core ing a major role. The increasing number For more information, visit: ❙❙www.rohde-schwarz.com/mobile-network-test networks as well baseband functions of things that will be communicating ❙❙www.rohde-schwarz.com/technology/lte of base stations. It would also enable with each other in the future (IoT) and ❙❙www.rohde-schwarz.com/technology/5G

Even today, signal generators and signal analyzers are used to evaluate potential 5G components. They are indispensable due to their flexibility in terms of frequency range, bandwidth and transmission technology. They are also essential compo- nents of measuring systems used to analyze propagation con- ditions in new, undefined frequency bands (see next article). Multiport network analyzers will play a decisive role in imple- menting future antenna technologies. And finally, the influ- ence of individual applications on data rates, signaling loads and current drain are under examination. This will be espe- cially important for IoT modules as it must be possible to measure individual applications on the IP layer itself.

Fig. 4: Mobile measuring receivers with directional antennas help opera- tors monitor operational networks and identify interference.

NEWS 214/16 13