Telecommunication Services provides a holistic approach to understand telecommunications systems by addressing the emergence and domination of new digital services, consumer and economic dynamics, and the creation of content by service providers.
* Includes services, underlying technologies, and internal capabilities for social network advertising
* Covers market dynamics that determine the successes and failures of service offerings
* Discusses the impact of smartphones (iPhone launch) on the telecommunications and mobile device industry
Antonio Sánchez works in one of the largest multinational telecommunications operator (Europe and Americas), and is an Honorary Collaborator at the University of Valladolid, Spain. He earned his MSc in Telecommunications Engineering and PhD in Telecommunications from the University of Valladolid. Dr. Sánchez is an IEEE Senior Member, and editor of IEEE Communications Magazine.
Belén Carro is an Associate Professor at the University of Valladolid, Spain, as well as the Director of Communication Services and Networks research group. She earned her MSc in Telecommunications Engineering and PhD in Telecommunications from the University of Valladolid. She has been guest editor for IEEE Network, IEEE Wireless Communications, and IEEE Communications Magazine.
Internet Services: From Broadband to Ultrabroadband
From the old times of very low-speed narrowband fixed dial-up and mobile 2G GPRS, telecom operators have been offering broadband access massively. The mobile network, being a shared medium, still lags the fixedline network in speed today, but in both cases the available speeds are already quite high and continue to increase.
The mobile network surpasses the fixed line network in terms of adoption. In 2015 there were already more than 3 billion mobile Internet subscribers (unique).1 This figure represents more than half of mobile subscribers (which includes those without Internet: almost 5 billion unique mobile subscribers-and 8 billion total mobile connections-by the end of 20162). Related to access device, smartphones already represented 45% of total mobile connections by the end of 2015.3 In what respects to technology, LTE (4G) achieved 1 billion connections milestone in 20154 (www.gsmaintelligence.com/, last accessed January 12, 2017).
In fixed broadband xDSL, copper-based technologies offer speeds that depend on the distance to the central office. Typical speeds are asymmetrical with downlinks having a few Mbps (megabits per second), increasing to several tens of Mbps with VDSL for closest buildings (or with fiber to an intermediate point-cabinet-in order to reduce the distance). Uplink is typically up to 1 Mbps. On the other hand, cable operators have been upgrading their networks by deploying fiber very close to customer premises, the so-called Fiber-to-the-Node, with coaxial cable left only to the last few meters to tens of meters. Based on DOCSIS (Data Over Cable Service Interface Specification) 3.0 specification, the cable network provides commercial speeds of several hundred Mbps and could reach up to 10 Gbps (gigabits per second) in the downstream and 1-2 Gbps in the upstream with improved modulation of DOCSIS version 3.1. or even 10 Gpbs symmetrical with full-duplex techniques, which is still in the R&D stage.5 Finally, FTTH is an All-IP network, which as its name implies deploying fiber end to end (central office to customer premises, home, or building plus LAN (Local Area Network)). Commercial speeds have already reached 10 Gbps symmetrical since 2014,6 although with limited coverage, and 1-2 Gbps symmetrical with broader coverage. In any case, technology could in principle provide higher speeds. In terms of coverage, there were (as of September 2015) 53 countries (with at least 200,000 households) that have at least 1% of homes subscribing to fiber (FTTH or Fiber-to-the-Building plus LAN), with top 6 in Asia (all above 50% household penetration).7
As opposed to fixed lines, mobile speed is more limited. Mobile networks are migrating from 3G to 4G, with main improvements in speed/capacity but also reduction in latency. 4G deployments are quite widespread, although the population coverage is not universal yet. The latest generation is LTE-Advanced (available in around 50 countries4) with the so-called carrier aggregation, which combines larger spectrum to increase speed. The maximum commercial advertised speed is 600 Mbps in downlink in Australia with the so-called Category 11 devices (under 3rd Generation Partnership Project (3GPP) standard).8 The modem supports 150 Mbps uplink, with new modems supporting even 1 Gbps downlink8 announced in early 2016 and commercial in second half 2016. However, it should be noted that the real speeds are much lower, given the fact that capacity is shared among all users connecting to the same base station.
Finally, operators are also offering Internet connectivity through WiFi, both in the fixed access (routers with WiFi) and in mobile access (offering multiple hotspots, sometimes through partnerships). With the new large available spectrum in 5 GHz and the recent 802.11ac standard, both capacity and speed have increased significantly.
Since broadband has a very positive impact on society, many governments are fostering universal coverage (e.g., Europe's ambition of providing 30 Mbps universally by 20209).
2.1 Customer Need: Connectivity and Social Inclusion
Since the inception of the Internet, connectivity has been embraced by billions of people, and even more to come, with availability and affordability the only limiting factors. Initially, people started to connect through dedicated systems (e.g., in government organizations) and then through modem dial-up, available to those with a fixed phone line. Given the fact that mobile lines are now much more widespread, the availability of mobile Internet made the figures skyrocketed.
Connectivity is the basic building block for any kind of digital services, some of which may not have been invented yet. Social networks and messaging are just two examples of applications based on connectivity that have surpassed the figure of 1 billion active users monthly.
Beyond this, connectivity can now be considered a social right, and that is why overcoming the digital divide is a top priority for governments. Connectivity is a proven mean of social inclusion, similar to enabling access to other basic rights like health and education. Along this line, there are rigorous studies that show the positive impact of connectivity in general and more specifically broadband in the Gross Domestic Product of an economy.10
2.2 Fixed Lines: Deploying Fiber Closer to Customer Premises: xDSL, Cable, FTTH
Access networks, as well as mobile networks, have rapidly evolved toward broadband. It has come a long way since the xDSL11-13 family started as a provisional upgrade of PSTN (Public Switched Telephone Network) and ISDN14 (Integrated Services Digital Network) narrowband access, and xDSL technology still survives but is being quickly replaced by other wired and wireless technologies.
Generally, at home, broadband access networks are wired: The xDSL copper wire family, the Hybrid Fiber-Coaxial (HFC) network, with fiber cores and coaxial distribution with a trend to evolving toward a complete fiber network,15 and the FTTH16 (Fiber-to-the-Home) networks. Also, mobile networks might be considered among broadband access networks because of their increasingly higher transmission rate, their wide coverage and a minimal amount of network installation, and the wide use of mobile terminals like smartphones.
A wired network is composed of a series of cables and other equipment between the local exchange of the operator and the network termination point that separates the client premises from the access network. The access network is the most important and expensive property of the operator, constantly evolving due to new service offers that imply new requirements such as more bandwidth, less latency, and so on, as well as regulatory changes.
xDSL (x Digital Subscriber Line) includes a family of Internet broadband access technologies based on the telephone subscriber loop (copper wire) digitalization. The main advantage of the xDSL family has traditionally been the reutilization of already deployed infrastructure with almost 100% coverage, partially or totally amortized. xDSL access is based on the conversion of the PSTN copper line to a high-speed digital line capable of supporting broadband services simultaneously with voice (with a channel located between 300 Hz and 3-4 kHz) with a minimum amount of interference. It should be noted that ISDN is not compatible with xDSL since it employs the xDSL lower frequency band and their spectra would be overlapped.
ADSL (Asymmetric Digital Subscriber Line) is the most common xDSL access technology, in which the uplink (from user to local exchange) and downlink (from local exchange to user) transmission rates are different due to the classic need for higher speed in the downlink demanded for traditional services like web browsing, video streaming, or email.
The main components of an ADSL link are the following:
- The ADSL Terminal Unit-Remote (ATU-R) or modem in the user premises
- The ADSL Terminal Unit-Central (ATU-C) or modem located in the telco premises, grouped in a DSLAM (Digital Subscriber Line Access Multiplexer) in the local exchange
A splitter must be placed before each modem. The splitter is a set of two filters: a high-pass filter and a low-pass filter that separate the low-frequency (telephony) and high-frequency (ADSL) signals.
ADSL employs Discrete MultiTone (DMT) modulation that is similar to OFDM (Orthogonal frequency-division multiplexing). It uses multiple subcarriers, each QAM modulated, with a separation of 4.3125 kHz and a bandwidth of 4 kHz for each subcarrier. When establishing the connection between the ATU-R and the ATU-C, the SNR is measured for each subcarrier band, and then the data flow is distributed depending on the SNR value: When the subcarrier SNR is high, it will transmit a higher data rate. DMT is a complex modulation scheme that enables the success of copper wire to transmit high data rates from the initial filter-limited 4 kHz used in traditional voice, but the modulation algorithm is translated into an IFFT (inverse fast Fourier transform) in the modulator and an FFT (fast Fourier transform) in the demodulator located on the other extreme of the loop making the DMT simpler to execute. Besides, these operations may be easily carried out developing the modem core on a DSP (Digital Signal Processor). DMT has two versions: DMT with FDM (frequency-division multiplexing) and DMT with echo cancellation. In DMT with...