LTE, LTE-A and LTE-A Pro Evolution

LTE is a standard for wireless communication and LTE Advanced / LTE Advanced Pro (Cat 6 to Cat 19) is a high-speed version of LTE, sometimes marketed as LTE+, 4G+, 4GX,4.5G or 4G LTE Ultra. LTE support varies from country to country, and the speed may vary depending on user location and how fast they’re traveling.


LTE (Cat 1~5)

  • LTE has been introduced in 2012 in order to provide high data rate mobile broadband connection.
  • It has been introduced to provide 10 times faster data rate compared to 3G.
  • LTE provides 100 Mbps.
  • LTE has been specified in 3GPP Rel.8.
  • LTE supports carrier bandwidth of 20 MHz.

LTE Advanced (Cat 6~16)

  • LTE Advanced is an enhancement to LTE with data rate increase to the factor of 10.
  • It supports carrier aggregation and higher order MIMO techniques.
  • It supports the data rate of 1 Gbps in downlink (From eNB to UE) and 500 Mbps in uplink direction (From UE to eNB).

LTE Advanced Pro (Cat 17~19)

  • It is enhanced version of LTE Advanced to support higher data rate beyond 3 Gbps.
  • It supports increased Bandwidth, increased efficiency and improved latency.
  • It makes use of both licensed (400 MHz to 3.8 GHz) and unlicensed (5GHz) spectrum to support up to 32 carriers of 20MHz each.
  • It is backward compatible with existing LTE and LTE Advanced devices.
  • It makes use of spectrum more efficiently by increasing number of antenna paths as well as multi beam approach. It serves single radio cell with 16 to 64 antenna paths.
  • It grows network capacity to about 200% without any additional spectrum or base stations.
  • Increased battery life about 10 times than LTE.

Vodafone: 5G tends to be overhyped

There is a strong tendency to override 5G, said Vodafone CTO Johan Wibergh at the Huawei Global Mobile Broadband Forum (HWMBBF) in London. The expectations of 5G are partially too big, on the other hand, many applications could also be implemented with LTE. He recalled that mobile phone generations are usually around 10 years up to date you can not say what will be possible in 2030 with 5G. Wibergh made a clear statement about UMTS: the 3G mobile phone network of Vodafone should be shut down in Europe from 2020.

4G Evolution and 5G New Radio

Many features that are currently often attributed to the next generation 5G mobile phones are easily possible with LTE, according to Vodafone CTO Wibergh. Gigabit speeds, very low latency times and IoT are easily possible with the latest LTE Advanced Pro (4.5G) networks. This is achieved by technologies such as 256QAM modulation, Massive MIMO antenna technology and bundling frequency ranges via carrier aggregation. Nevertheless, 5G offers tangible advantages, of course: with additional radio spectrum (“New Radio”), first in the range around 3.5 GHz, extremely high bandwidths become possible, for example. According to Wibergh, 5G is also about 10 times more cost-efficient than LTE.

UMTS will be switched off from 2020

A very interesting statement made by Vodafone CTO Wibergh on the topic of UMTS: the 3rd mobile generation should be switched off gradually in Europe from 2020, even before GSM/2G. The radio spectrum can be used much more efficiently with LTE or 5G.


The shutdown of 3G is unlikely to be noticeable to users, on the contrary, the transition to new technologies will be fluid. Vodafone uses its previously used exclusively spectrum in the range of 2100 megahertz for UMTS frequency, partly for LTE. This is likely to be the case more often in the future, as long as Vodafone acquires spectrum in the 2100 MHz range at the next frequency auction.

EPC: A new core network for the new LTE radio technology

Many new transmission facilities to the cellular towers are visible part of the LTE structure.


The second, invisible to the public, is equally important part: The technology and infrastructure with which these new LTE transmission facilities are operated and controlled, the so-called core network, changes radically. This core network for LTE (Engineered packet-based core network) and Evolved Packet Core Evolved Packet or designated system. It basically works like the normal Internet, the technical term for this technology is an IP-based network or English an all-IP network. But what does that mean and how this network is different from a GSM network or a UMTS network, so what is the new in it?

GSM, UMTS and LTE networks: the differences

Put simply, the current mobile phone networks were completely fixed, or in large part on voice telephony. The GSM network, the second generation of mobile phone was originally designed as a pure network; other functions such as SMS and data transmission were then gradually it. The UMTS network calls and sending large amounts of data as equal functions together. The core network is divided into a part of UMTS, which provided fixed channels for the transmission of telephone calls (circuit switched) and one of the different data sets – like the Internet – transported.

The LTE network has – like the Internet – the absolute data priority. Telephoning is thus only one of many sub-functions of data transmission. A development is reconstructed, which is advanced in the fixed network have further calls is no longer handled through a separate channel, but runs as a Voice over IP over the Internet.

Which then affects the manner in which the LTE core network works: It is anything from one terminal to the other terminal to the Internet technology – are transmitted – the Internet Protocol, or IP. Technically speaking, it is an IP-based network or an all-IP network.

This fundamental change in the net makes the data transmission speed – both for downloading and sending, as well as in the reaction times. The Australian IT specialist Stuart Corner says: It is not primarily be the new LTE data radio technology, which allows high speed jumps, but most of all the new core network.

Signaling data: By registering for the bill

The new network is allocated differently: Over a part of running the so-called signaling data – for example, the registration of the participant in the network, its verification and identification, the location of their mobile device – the other part of the so-called user data – ie services that he accepts the scheme as phone or mobile Internet.

Among the parts that manage the signaling data and edit include Management Mobility Entity, short MME (Management of the mobile units), the Home Subscriber Server, short HSS (Subscriber Server) and the Policy and Charging Rules Function, briefly PCRF (fees office).

Logs in the MME to the mobile device, and then is forwarded to a location which the services – manages – ie the data transmissions. The MME also retrieves the information about the customer at HSS – because they are deposited there, in the GSM and UMTS networks had this customer database the name of Home Location Register (HLR). The PCRF can – depending on the rate – to specific data flows from that terminal or declines; it calculates how much the service costs at the rate reserved by the customer and shall issue an invoice.

User data: designing services funneled through the net

The services themselves are carried out in the so-called SAE gateway. The acronym stands for System Architecture Evolution Gateway – and said in German as the main interface for the network. This gateway consists of two areas: First, since the serving gateway is – short SGW in German about services portal. There the user’s terminal is managed by the application at the MME continues. It remains registered so when the user switches between two cell towers or when switching from LTE to a different wireless technology. It takes the data packets received by the user sends – for example by surfing – and forwards it to the exit.

The output is referred to as PDN Gateway, which is German for Public Data Network Gateway as portal to the public networks. And that is its function: Here the data to other networks – other mobile networks, Internet – forwarded and received the input data for the terminal of customers and forwarded.


LTE Networks: The Architecture

The architecture of LTE networks is given the technical term System Architecture Evolution or the corresponding abbreviations SAE.


It is compared to previous wireless networks and provides a simpler structure to process with greater amounts of data. Thereby it provides a faster response time of the entire network. The new architecture is also the seamless mobility between LTE and other wireless technologies such as GPRS or WiMAX. Finally, the new architecture could transform the wireless network to an all-IP network. This means the data packets are sent to the wireless network in the Internet-standard. In order for mobile devices, IP-based services such as IPTV, online games, or data transfer from the Internet, but also Internet telephony is optimized.

EUTRAN: The wireless network

As with any wireless network even in the LTE, radio network consists of individual cells. The device of the user need the radio signals from the base station, from there to the base station – in LTE it is called eNodeB. Transmission tower and base station form a cell.

In LTE radio network, several adjacent radio cells are combined to form a group, which are known as the Tracking Area. The entire radio part, that all radio cells and tracking areas of an operator is taken together, the technical English with E  UTRAN or EUTRAN called. The term EUTRAN is from the initials of Evolved Universal Terrestrial Radio Access Network formed. This part of the network is also referred to as air interface.

EPC: The core network

The user’s data are going to the core network Of the air interface for LTE, which in technical English Evolved Packet Core ( EPC is called). The Evolved Packet Core consists of three components:

The first is the MME. This abbreviation stands for Mobility Management Entity. An MME manages multiple tracking areas. The MME is the most important control element in the EPC; it is only responsible for control signals. The MME is responsible for the mobility management, which means that they registered and be identified by the exact location of the user, which is a terminal in the LTE network. In the MME, it’s possible to notify the user to speak with his terminal.

The MME also organizes the recognition of the user, or finds his admission. Detection of the user accesses the MME to a database, in which the participants are recorded, this means in English technical HSS (Home Scriber server). His profile is stored in the MME. the MME sets the key, after the data is encrypted and sends it to the base station – or the eNodeB – which performs the encryption. When the terminal is turned on, the MME calls him an SGW.

This SGW (short for English Service Gateway) is the second component of an LTE network. The service gateway remains the focal point for the user’s device when it switches between two LTE transmission towers or when the LTE network must switch to UMTS or GSM network. The SGW is a switching station – it switches the users coming from or addressed to him data to the correct address.

By the user sent or addressed to him, data runs over the third component: the Public Data Network Gateway (symbol: PGW, meant: Interface for public data networks). The PGW is as it were a terminal, where the user’s data from the network of the mobile operator forwarded to other networks or in the data arriving from other networks for him, ready to collect.

The terminal of a user is able to communicate with a plurality of PDN-GW – if it is responsive simultaneously different networks. The PDN gateway also sends data to a computing unit, which is outside of the core network, the PCRF (Policy and Charging Rules Function).

The user directory and the accounting office

This brings us to the two parts of which are outside of the core network, however, associated with this are: the Home Server Scriber, short HSS are the user data, including a profile stored. He is like a complete list of all customers of a mobile operator. Here, for example, the identification number (IMSI) of the mobile subscriber is stored or which services are allowed for him. There will also be stored at which the MME device was last logged.

The accounting and control station is finally in the part that policy and charging rules function (PCRF) is called. It’s noted that the types of data that arrive in the PGW can be used by the customer, and if so, under which tariff they fall. Using this information the bill then finally can create.


To increase the data rate, a modulation method is used in LTE, which can transmit a plurality of bits per signal – the so-called Quadrature Amplitude Modulation (QAM).

This is a transmission technology in the long applied modulation method, which guarantees high transmission density. This amplitude modulation and phase modulation are combined. The method has different levels, and it can have multiple bits in groups of 4, 8, 16, 32 or 64 bits are combined – correspondingly increases, the transmitted data rate. The method with 64-bit, 64 short is called QAM, however, it is only possible in the vicinity of the transmission mast, because the higher the modulation, the more susceptible to interference. Thus, in LTE systems it uses in further transmission distance 4 QAM, 16 QAM in a medium distance.

In practice, therefore, the data rate close to the LTE radio mast will be higher than in a clear distance. The announced top speeds with LTE are therefore also dependent on how far away the nearest transmission tower, where the customer is staying.

QAM applications

QAM is in many radio communications and data delivery applications. However, some specific variants of QAM are used in some specific applications and standards.

For domestic broadcast applications for example, 64 QAM and 256 QAM are often used in digital cable television and cable modem applications. In the UK, 16 QAM and 64 QAM are currently used for digital terrestrial television using DVB – Digital Video Broadcasting. In the US, 64 QAM and 256 QAM are the mandated modulation schemes for digital cable as standardized by the SCTE in the standard ANSI/SCTE 07 2000.

In addition to this, variants of QAM are also used for many wireless and cellular technology applications.


QAM noise margin

While higher order modulation rates are able to offer much faster data rates and higher levels of spectral efficiency for the radio communications system, this comes at a price. The higher order modulation schemes are considerably less resilient to noise and interference.

As a result of this, many radio communications systems now use dynamic adaptive modulation techniques. They sense the channel conditions and adapt the modulation scheme to obtain the highest data rate for the given conditions. As signal to noise ratios decrease errors will increase along with re-sends of the data, thereby slowing throughput. By reverting to a lower order modulation scheme the link can be made more reliable with fewer data errors and re-sends.


The MIMO antenna technology in LTE

In LTE wireless networks, MIMO antenna technology is used. MIMO stands for Multiple Input / Multiple Output.


Instead of a sending and receiving antenna, in the MIMO technology, up to four transmitter antennas and four receiver antennas to be used. The corresponding codes are 4×4 four transmitting and receiving antennas, or 2×2 for two transmitting and receiving antennas. MIMO enables simultaneous transmitting multiple data streams on the same frequency. Systems with a single antenna are called SISO (Single Input / Single Output).

In principle, the multiple-antenna systems have the following advantages: First, you get a bigger reception power and thus greater range, secondly suppress interference from other radio waves better, make for a better connection quality thirdly and fourthly, for better transfer rates. However, one cannot utilize all four at the same time maximum benefits: You have to decide whether you want to improve the system in a data-transfer speed or the range or quality of the connection.

Key technology for LTE

MIMO is a key technology in LTE wireless networks, since they are the spectral efficiency is improved. However, MIMO is not only used on LTE, but also used in WiMAX and WLAN systems. By using multiple antennas, in LTE, the reception signal improved and interference can be reduced – that is, it results in less interference from other radio frequency used. But the most important: The MIMO technology is at the LTE transmission of the data stream to be distributed to up to four transmit and receive antennas. This increases the amount of data that is transferred per unit time, thus ensures a higher transmission speed – while reducing the error rate.

LTE can use up to four times four antennas, it provides for the 3GPP Release 8, which is defined in the technical specifications for LTE. Also two times two MIMO systems are possible. In a 2×2 MIMO, the data rate in comparison to a system can be doubled with a respective antenna almost.

Devices with MIMO antennas

A technical challenge may be the equipment of devices with multiple antennas – a smartphone offers relatively little room for a higher number of antennas. At low frequencies such as the 800-megahertz band, the problem is compounded by the fact that there are larger antennas needed. Especially in the countryside, however, LTE will use this frequency range. Installation of multiple antennas in laptops is problematic. Since the LTE stations will initially replace the missing country’s DSL, it imposes the use of MIMO technology is quite well possible.


LTE Versions: TDD and FDD

LTE is available in two technical variants: TDD and FDD. TDD stands for the English expression Time Division Duplex.FDD stands for the English word Frequency Division Duplex. It sounds complicated, but you can explain it simply: When FDD there are two channels, which is broadcast on: on one which you receive messages with their laptop or smartphone and on the other which you send the message. In TDD there is only one channel – it will be used alternately to send and receive. Transmit and receive mode switch it so fast that you do not notice. What are the advantages and disadvantages of both techniques?

The advantages and disadvantages of the techniques

FDD seems better at functions where many data are simultaneously transmitted and received – they both have their own supervised channel. One example would be telephone calls or video calls. Another benefit: When building the base stations need to take any further precautions – as transmit and receive channels are different, disrupt the channels of two base stations are not mutually exclusive. In TDD networks have to ensure that adjacent base stations do not interfere with each other.

Conversely, TDD uses the available space in the radio room much better. Often more data is received than sent, or more sent than received – for example, if I put a video on the Internet or send a friend a photo collection. In these cases – in technical terms, these are asymmetrical applications – TDD divides the space to send or receive on demand. Overall, the introduction of this TDD technology is cheaper, among other reasons, because the mobile operators do not have to hire as much radio room from the state as in FDD. The TDD needs only one channel and not two. For operators who previously used the wireless technology WiMAX, the transition to LTE TDD, with a lower price.

FDD and TDD: Worldwide both lay sometime par

Currently, the FDD technology is well forward, but with increasing global expansion of LTE networks, two techniques are commonly used equally well. The currently existing LTE networks in Germany, Austria, Scandinavia and the Baltic use FDD-LTE. Even Verizon Wireless in the U.S. uses this variant.

However, LTE is in TDD variant currently being tested by E-Plus in Germany. LTE TDD has also been tested in France, Ireland, Poland; the United States has the Wimax operator Clearwire tested. And WiMAX is interested in the technology in Japan, Saudi Arabia, Oman and Taiwan.

In South Korea, the Korean SK Telecom in early July has taken a LTE network on TDD base into operation in Malaysia still 2011; a TDD-LTE network will be built. Russia wants the operator Yota use a nationwide 180 cities comprehensive LTE network TDD. Experts believe that China has in each case; the TDD variant will be used for LTE, as well as in India.


LTE Technology

The new mobile technology LTE is superior to the existing mobile technologies GSM and UMTS, the link speed which data is transferred is much far higher the response time of the current system and the connection is faster.


This is achieved through a variety of improvements in various areas of technology that each contribute in itself to significantly better overall picture of the data radio technology. Due to the significant improvement in overall performance, LTE mobile technology is increasingly recognized as the 4th Generation (4G) refers. While in technical descriptions of the generation LTE 3.9 is assigned, but the name of LTE as 4G mobile technology is likely to prevail worldwide.

Improvements in wireless technology

A number of technical innovations allow use of the available radio room better. The OFDMA radio technology allows customizing the transmission capacity to meet the needs of each user – who wants to watch TV on the mobile Internet, gets more space than someone who just wants to make calls only. The downlink OFDMA is used for the same transmission speed with a very small range of the radio room – it takes up less space for an equal amount of data transmitted. Also known as High Speed OFDM Packet Access (HSOPA) technology uses the existing radio room two to four times better than the method called Wideband Code Division Muliple Access (WCDMA), which is used in HSDPA.

With the multi-antenna MIMO technology can be transmitted simultaneously with the current standard of four antennas and received simultaneously – what the reception improves performance significantly. Moreover, a possible interference by neighboring radio waves, which prevents so-called interference significantly stronger.

All in all, the radio room with LTE is better used, because the signals from the multiple antenna technology at transmission and reception are separated in space, and because the size of the radio channels can be adjusted according to the user.

Improvement in network construction

There are also improvements in network construction. The networks as a whole should be fit. In the network architecture, the requisite leaner architecture makes first by the absence of an element – namely the mediator between the base station and core network noticeable. The significantly higher amount of data that can be processed thanks to improved techniques the radio part of the network, of course, lead to the fact that mobile operators must also provide the lines between the base station and core network for more capacity.

Overall, the whole network will be improved so that its response times are less than five thousandths of a second (milliseconds). After all, only at a very low response time (latency) of the network can be demanding services such as Mobile TV, video calls and mobile online games provide no problems.

The competition techniques: Ultra Mobile Broadband and Mobile Wimax

LTE is the view of IT expects to be the first mobile technology, which works worldwide as a general standard. Nevertheless, there were – from a technical viewpoint – two other data transmission technologies that were considered LTE competitors: Mobile WiMAX and Ultra Mobile Broadband are techniques that offer similar data transfer speeds as the mobile technology LTE.

Ultra Mobile Broadband was a technology that is used in the USA the third mobile communications standard Should develop a rapid generation CDMA2000 mobile fourth generation. Above all, the U.S. chip maker Qualcomm invested diligently in the development based on CDMA 2000, while the Swedish Ericsson continued to LTE as a new cell phone technology. Both technologies used very similar approaches. In November 2008, Qualcomm ended its funding of research and waved a UMB to LTE.

Mobile WiMAX can achieve with the use of LTE and multi-antenna MIMO method on a 10-megahertz radio channel transmission speeds of a total of 90 megabits per second. These are divided in 63 megabits per second for downloading data (downlink) and 28 Mbit/s for transmission (uplink). However, radio cells are in Mobile Wimax achieved with a diameter of one to four kilometers far smaller than the LTE radio cell in the 800 megahertz range – where the diameter is 20 kilometers.

For network design brings dramatic benefits for this difference. LTE takes much less Send master and base stations to build a nationwide network.


LTE Speed

The new mobile technology Long Term Evolution (LTE ) promises particularly high rates of data transmission: Both when downloading from the internet, and when sending data, the speed is much faster than the older LTE wireless data technology UMTS with HSPA.

LTE Receiving data

In LTE networks, which are currently being commonly built in Asia and Europe, the operation speeds of theoretically up to 50 megabits per second (Mbit/s) when receiving data are already available. HSPA+, fastest wireless technology in 3G mobile network enables downloading of theoretically up to 43.2 Mbit/s.

LTE may actually even more. However, at speeds up to one gigabit per second (Gb/s) are possible only under laboratory conditions. The data rate depends on several factors. Determined the width of a frequency channel, the amount of data can be sent simultaneously. Several antennas increase in the transmitter and the receiver velocity.

What is the real average speeds will be using LTE in reality remains to be seen. In the U.S. you get in well-developed LTE network of Verizon Wireless at an average speed of about 10 megabits per second and can compete with DSL connections.

The transmission of data

When sending data rates, download can also be achieved, far higher mathematically than the current transmission rate. Technically feasible there are theoretical data rates of up to 86.4 Mbit/s.

Once again, we will have to see how high the rate offered is real then. It is determined by the technology, but also through the utilization of the radio cell or the distance of the user to the transmission tower.


LTE Advanced- beyond the next Step

The evolution of LTE (Long Term Evolution) is already developed. LTE Advanced is to say the new technology.


The Third-Generation Partnership Project (3GPP) specifies in its Release 10, the objectives of LTE-Advanced. The mobile technology corresponds to the 3GPP LTE Release 8 LTE Advanced is to be backward compatible. Not only are the transfer rates expected to rise with LTE Advanced. The use of multiple antennas and the incorporation of relay stations are to be carried forward.


More bandwidth

The bandwidth is LTE-Advanced is significantly higher than the LTE in Release 8. Instead of 20 megahertz, LTE-Advanced can bundle multiple carriers and thus use up to 100 MHz simultaneously. Here may also be combined in different frequency bands, frequency ranges – important because no carrier has been on a continuous frequency range of 100 MHz. Currently these 100 MHz are only in theory, in practice more spectra are assigned. This can happen only in 2015 at the World Radio Conference (WRC). Until then, the bandwidth will probably be limited to 40 MHz.

Another innovation that will keep up with LTE-Advanced collection is called “relay nodes”, i.e. relay stations. This will allow, even outside the range of a base station to receive the signal. In the edge region the signal reinforces relay stations. Connected the relay stations means connected to the base station. Thus, the signal strength inside buildings can be improved.

Interference use

Another method that could be introduced with LTE Advanced is CoMP (Coordinated Multi-Point). This is a problem to be addressed, which often occurs, especially in densely populated areas. There where many transmission towers are in a confined space, to their ranges and signals often overlap. This interference occurring far as disorder should be used wisely with the CoMP process. If interference is likely, future base stations preprocess messages for multiple users together prior to transmission. By preprocessing, signals are superimposed on the desired user device design, but are eliminated at the antennas of other users.