Tutorial – 4G Wireless Technologies


What Is 4G Wireless?

4G, short for fourth-generation wireless communication systems, has engaged the attention of wireless operators, equipment makers (OEMs), investors, and industry watchers around the world.  4G refers to the next generation of wireless technology that promises higher data rates and expanded multimedia services.  Since, at this point, 4G is more of an aspiration than a standard, there is not an agreement yet on what should constitute 4G.

Since the ITU is a major force in the standardization of telecommunications technologies, it’s worth looking at the ITU’s performance goals for 4G:

  • “The framework for 4G systems should fuse elements of current cellular systems with nomadic wireless-access systems and personal-area networks in a seamless layered architecture that is transparent to the user”
  • “Data rates of 100 Mbps for mobile applications and 1 Gbps for nomadic applications should be achievable by the year 2010.”
  • “Worldwide common spectrum and open, global standardization should be pursued”.

As another viewpoint, the Wireless World Research Forum (WWRF) defines a 4G network as one that operates on Internet technology, combines it with other applications and technologies such as WiFi and WiMAX, and runs at speeds ranging from 100 Mbps (in cell-phone networks) to 1 Gbps (in local WiFi networks). There is some debate among standards bodies and industry watchers as to whether WiMAX is, or will become, a full-fledged 4G technology competitive with 4G wireless.

From Performance Goals to a Standard

The process of developing a standard is a long one, carried out by several groups, which include Standards Development Organizations (SDOs), industry forums, and companies, such as OEMs, that have a stake in the end product.  Some of the major SDOs are nonprofit regional or governmental bodies, such as ETSI in Europe, CCSA in China, and the TTA in Korea. 3GPP and 3GPP2 are examples of industry SDOs that develop and maintain standards for current 2G and 3G technologies.  In 2007, the ITU will convene a global congress to set a course for the 4G standards development process.  It is doubtful that we will see an ITU standard before 2010 or beyond. Nor are standards necessarily the final word on the subject.  Standards are what various groups are willing to agree to after years of negotiation.  In the meantime, there is nothing to stop the various SDOs and wireless operators from deploying so-called 4G systems without waiting for the completion of the formal standards process.

Progress to Higher Data Rates — But Short of a Defined 4G Standard

The CDMA development group (CDG) based in the United States is pushing the 1xEV-DO speeds to what they hope will qualify it as a 4G technology.   InRevision C they plan to use CDMA, TDM, OFDM and MIMO (Multiple Input Multiple Output) and even the Space Division Multiple Access advanced antenna to increase the download speeds up to 280 Mbps. This new standard will be called Ultra mobile Broadband.

Japan’s NTT DoCoMo and Korea’s Samsung are testing a 4G communication system prototype called Variable Spreading Factor Orthogonal Frequency and Code Division Multiplexing (VSF-OFCDM) at 100 Mb/s while moving, and 1 Gb/s while stationary (or “nomadic” in ITU terms).   NTT DoCoMo and Samsung both plan on launching the first such commercial network in 2010.

One alternative to 4G being proposed is the 3GPP LTE (Long Term Evolution) project.   It is the name given to an initiative within the Third Generation Partnership (3GPP) Project for the ongoing enhancement of the UMTS 3G standard.. The LTE project is not a standard, but it will establish a “4G like” capability for UMTS operators.Among all these technologies, several research organizations think 3G LTE holds the most promise.  3G LTE, sometimes called 3.99G, is also being hyped as “Super 3G”.

Emerging 4G Access and Capacity Schemes

Recent years have seen major advances in wireless access technologies.   Among the new schemes being proposed for 4G, 802.16e and 802.20 standards are OFDMA, Single Carrier FDMA, and MC-CDMA. The new technologies, while offering the efficiencies of the older technologies such as CDMA, also offer advantages in scalability.  Current working assumptions for physical layer multiple access schemes is OFDMA for downlink and Single Carrier FDMA (SC-FDMA) for uplink.

One way to increase system capacity is to implement a Multiple-Input Multiple-Output (MIMO) antenna scheme. A wireless system with single antennas obeys Shannon’s classical limit for capacity, which can be expressed as C = log2(1+SNR). Ideal capacity therefore increases as the log of the signal-to-noise ratio. MIMO systems, on the other hand, increase capacity linearly with respect to the number of transmit and receive pairs that are used.

The Spectrum Bottleneck

The 4G migration, while holding great promise for high data rate services and a broad range of multimedia applications, will require additional radio spectrum. The FCC opening of the 700 MHZ band through the auction process is a possible solution for 4G deployment in the U.S.   However, use of this band for mobile wireless services is years away due to the complexities of reallocating existing broadcast licenses.  Moreover, there is little chance of establishing a common 4G spectrum plan on global basis. The lack of a unified spectrum plan for mobile wireless networks was obvious with the rollout of 2G and 3G networks.

Business Implications for 4G

4G technology will not be a major factor in the wireless market in the next four to five years.   During early 2007, operators will most likely be choosing between investments in 15 year-old GSM technology or newer 3G technologies like CDMA2000 1xEV-DO, WCDMA, and HSDPA which offer greater network capacity and lower cost to deliver emerging multimedia service as well as broadband data.  4G will not be available as a business option until the ITU and the national standards groups like the 3GPP and 3GPP2 organizations have completed the development of a formal 4G standard.

Recap and Conclusions

  • The Internet is the driving force for higher data rates and high speed access for mobile wireless users. This will be the motivation for an all mobile IP based core network evolution.
  • The market may not be able to support two incompatible wireless mobile technologies such as 4G wireless cellular networks and mobile WiMAX.
  • OFDM and MIMO are the largest strongest candidates for 4G access technologies.
  • NTT DoCoMo and Samsung are the world leaders in testing and rolling out so called “3.99G” technologies.   Lessons learned here may influence the direction and technology path for 4G in the next 4 years.
  • The lack of radio spectrum suitable for 4G deployments will be a major impediment to the migration of 3G to 4G networks, especially in the U.S.

How to Learn More about It


  • If you are already familiar with 3G and 3+G technologies such as UMTS, HSDPA, and HSUPA, you can learn more about the evolving 3G LTE/4G technologies by taking the 3-day  course on LTE.
  • For a great all-in-one course on all major wireless technologies, consider the 5-day All Wireless course.

Books and Other

  • Advanced Cellular Network Planning and Optimisation: 2G/2.5G/3G…Evolution to 4G

by Ajay R. Mishra (Editor).  John Wiley Inc., 2007.

  • Wireless Technology: Waiting for 4G, Bernstein Research, September 25, 2006.
  • “Race for the future: The 3G mobile migration”, Telephony, September 11, 2006.


Web Resources

  • Lynnette Luna, “Reality game- the standards process as it exists today”, Mobile Radio Technology, January 1, 2007