Peter Lobner

The 5^th generation of mobile telephony and data services, or 5G, soon will be arriving at a cellular service provider near each of us, but probably not this year. To put 5G in perspective, let’s start with a bit of telecommunications history.

1. Short History of Mobile Telephony and Data Services

0G non-cellular radio-telephone service:

• 1946 – Mobile Telephone Service (MTS): This pre-cellular, operator assisted, mobile radio-telephone service required a full duplex VHF radio transceiver in the mobile user’s vehicle to link the mobile user’s phone to the carrier’s base station that connected the call to the public switched telephone network (PSTN) and gave access to the land line network. Each call was allocated to a specific frequency in the radio spectrum allocated for radio-telephone use. This type of access is called frequency division multiple access (FDMA). When the Bell System introduced MTS in 1946 in St. Louis, only three channels were available, later increasing to 32 channels.

• 1964 – Improved Mobile Telephone Service (IMTS): This service provided full duplex UHF/VHF communications between a radio transceiver (typically rated at 25 watts) in the mobile user’s vehicle and a base station that covered an area 40 – 60 miles (64.3 – 96.6 km) in diameter. Each call was allocated to a specific frequency. The base station connected the call to the PSTN, which gave access to the land line network.

1G analog cellular phone service:

• 1983 – Advanced Mobile Phone System (AMPS): This was the original U.S. fully automated, wireless, portable, cellular standard developed by Bell Labs. AMPS operated in the 800 MHz band and supported phone calls, but not data. The control link between the cellular phone and the cell site was a digital signal. The voice signal was analog. Motorola’s first cellular phone, DynaTAC, operated on the AMPS network.
  •  AMPS used FDMA, so each user call was assigned to a discrete frequency for the duration of the call. FDMA resulted in inefficient use of the carrier’s allocated frequency spectrum.
  • In Europe the comparable 1G standards were TACS (Total Access Communications System, based on AMPS) and NMT (Nordic Mobile Telephone).
  • The designation “1G” was retroactively assigned to analog cellular services after 2G digital cellular service was introduced. As of 18 February 2008, U.S. carriers were no longer required to support AMPS.

2G digital cellular phone and data services:

• 1991 – GSM (Global System for Mobile), launched in Finland, was the first digital wireless standard. 2G supports digital phone calls, SMS (Short Message Service) text messaging, and MMS (Multi-Media Message). 2G networks typically provide data speeds ranging from 9.6 kbits/s to 28.8 kbits/s. This relatively slow data speed is too slow to provide useful Internet access in most cases. Phone, messages and the control link between the cellular phone and the cell site all are digital signals.
  •  GSM operates on the 900 and 1,800 MHz bands using TDMA (time division multiple access) to manage up to 8 users per frequency channel. Each user’s digital signal is parsed into discrete time slots on the assigned frequency and then reassembled for delivery.
  • Today GSM is used in about 80% of all 2G devices

• 1995 – Another important 2G standard is Interim Standard 95 (IS-95), which was the first code division multiple access (CDMA) standard for digital cellular technology. IS-95 was developed by Qualcomm and adopted by the U.S. Telecommunications Industry Association in 1995. In a CDMA network, each user’s digital signal is parsed into discrete coded packets that are transmitted and then reassembled for delivery. For a similar frequency bandwidth, a CDMA cellular network can handle more users than a TDMA network.

• 2003 – EDGE (Enhanced Data Rates for GSM Evolution) is a backwards compatible evolutionary development of the basic 2G GSM system. EDGE generally is considered to be a pre-3G cellular technology. It uses existing GSM spectra and TDMA access and is capable of improving network capacity by a factor of about three.

•  In the U.S., some cellular service providers plan to terminate 2G service by the end of 2016.

3G digital cellular phone and data services:

• 1998 – There are two main 3G standards for cellular data: IMT-2000 and CDMA2000. All 3G networks deliver higher data speeds of at least 200 kbits/s and lower latency (the amount of time it takes for the network to respond to a user command) than 2G. High Speed Packet Access (HSPA) technology enables even higher 3G data speeds, up to 3.6 Mbits/s. This enables a very usable mobile Internet experience with applications such as global positioning system (GPS) navigation, location-based services, video conferencing, and streaming mobile TV and on-demand video.
  •  IMT (International Mobile Telecommunications) -2000 accommodates three different access technologies: FDMA, TDMA and CDMA. Its principal implementations in Europe, Japan, Australia and New Zealand use wideband CDMA (W-CDMA) and is commonly known as the Universal Mobile Telecommunications System (UMTS). Service providers must install almost all new equipment to deliver UMTS 3G service. W-CDMA requires a larger available frequency spectrum than CDMA.
  • CDMA2000 is an evolutionary development of the 2G CDMA standard IS-95. It is backwards compatible with IS-95 and uses the same frequency allocation. CDMA2000 cellular networks are deployed primarily in the U.S. and South Korea.

• 3.5G enhances performance further, bringing cellular Internet performance to the level of low-end broadband Internet. With peak data speeds of about 7.2 Mbits/sec.

4G digital cellular phone and data services:

• 2008 – IMT Advanced: This standard, adopted by the International Telecommunications Union (ITU), defines basic features of 4G networks, including all-IP (internet protocol) based mobile broadband, interoperability with existing wireless standards, and a nominal data rate of 100 Mbit/s while the user is moving at high speed relative to the station (i.e., in a vehicle).

• 2009 – LTE (Long Term Evolution): The primary standard in use today is known as 4G LTE, which first went operational in Oslo and Stockholm in December 2009. Today, all four of the major U.S. cellular carriers offer LTE service.
  • In general, 4G LTE offers full IP services, with a faster broadband connection with lower latency compared to previous generations. The peak data speed typically is 1Gbps, which translates to between 1Mbps and 10Mbps for the end user.
  • There are different ways to implement LTE. Most 4G networks operate in the 700 to 800 MHz range of the spectrum, with some 4G LTE networks operating at 3.5 GHz.

2. The Hype About 5G

The goal of 5G is to deliver a superior wireless experience with speeds of 10Mbps to 100Mbps and higher, with lower latency, and lower power consumption than 4G. Some claim that 5G has the potential to offer speeds up to 40 times faster than today’s 4G LTE networks. In addition, 5G is expected to reduce latency to under a millisecond, which is comparable to the latency performance of today’s high-end broadband service.

With this improved performance, 5G will enable more powerful services on mobile devices, including:

• Rapid downloads / uploads of large files; fast enough to stream “8K” video in 3-D. This would allow a person with a 5G smartphone to download a movie in about 6 seconds that would take 6 minutes on a 4G network.
• Enable deployment of a wider range of IoT (Internet of Things) devices on networks where everything is connected to everything else and IoT devices are communicating in real-time. These devices include “smart home” devices and longer-lasting wearable devices, both of which benefit from 5G’s lower power consumption and low latency.
• Provide better support for self-driving cars, each of which is a complex IoT node that needs to communicate in real time with external resources for many functions, including navigation, regional (beyond the range of the car’s own sensors) situation awareness, and requests for emergency assistance.
• Provide better support for augmented reality / virtual reality and mobile real-time gaming, both of which benefit from 5G’s speed and low latency

3. So what’s the holdup?

5G standards have not yet been yet and published. The ITU’s international standard is expected to be known as IMT-2020. Currently, the term “5G” doesn’t signify any particular technology.

5G development is focusing on use of super-high frequencies, as high as 73 GHz. Higher frequencies enable faster data rates and lower latency. However, at the higher frequencies, the 5G signals are usable over much shorter distances than 4G, and the 5G signals are more strongly attenuated by walls and other structures. This means that 5G service will require deployment of a new network architecture and physical infrastructure with cell sizes that are much smaller than 4G. Cellular base stations will be needed at intervals of perhaps every 100 – 200 meters (328 to 656 feet). In addition, “mini-cells” will be needed inside buildings and maybe even individual rooms.

Fortunately, higher frequencies allow use of smaller antennae, so we should have more compact cellular hardware for deploying the “small cell” architecture. Get ready for new cellular nomenclature, including “microcells”, “femtocells” and “picocells”.

Because of these infrastructure requirements, deployment of 5G will require a significant investment and most likely will be introduced first in densely populated cities.

Initial introduction date is unlikely to be before 2017.

More details on 5G are available in a December 2014 white paper by GMSA Intelligence entitled, “Understanding 5G: Perspectives on Future Technological Advances in Mobile,” which you can download at the following link:

https://gsmaintelligence.com/research/?file=141208-5g.pdf&download

Note that 5G’s limitations inside buildings and the need for “mini-cells” to provide interior network coverage sound very similar to the limitations for deploying Li-Fi, which uses light instead of radio frequencies for network communications. See my 12 December 2015 post for information of Li-Fi technology.

15 July 2016 Update: FCC allocates frequency spectrum to facilitate deploying 5G wireless technologies in the U.S.

On 14 July 2016, the Federal Communications Commission (FCC) announced:

“Today, the FCC adopted rules to identify and open up the high frequency airwaves known as millimeter wave spectrum. Building on a tried-and-true approach to spectrum policy that enabled the explosion of 4G (LTE), the rules set in motion the United States’ rapid advancement to next-generation 5G networks and technologies.

The new rules open up almost 11 GHz of spectrum for flexible use wireless broadband – 3.85 GHz of licensed spectrum and 7 GHz of unlicensed spectrum. With the adoption of these rules, the U.S. is the first country in the world to open high-band spectrum for 5G networks and technologies, creating a runway for U.S. companies to launch the technologies that will harness 5G’s fiber-fast capabilities.”

You can download an FCC fact sheet on this decision at the following link:

https://www.fcc.gov/document/rules-facilitate-next-generation-wireless-technologies

These new rules should hasten the capital investments needed for timely 5G deployments in the U.S.