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.