Microwave Journal

FAQs - 4G and Future Directions in Cellular Wireless Standards

November 2, 2010
Courtesy of TriQuint Semiconductor

Q: What is 4G and where does it fit in the development of cellular communication standards?

A: 4G refers to the Fourth Generation of cellular wireless standards.

The First Generation (1G) of cellular wireless supported analog mobile phones. This transitioned to Second Generation (2G) digital service, which offered a significant upgrade in capabilities. The Third Generation (3G) supports multi-media, spread-spectrum transmission with larger volumes of data transfer and improved speeds. It enables numerous applications including e-mail and web browsing.

Fourth Generation (4G) takes the capabilities of wireless a step further. 4G increases bandwidth and modulation complexity and adds spatially multiplexed data streams (MIMO). This in turn increases the data rates and enables exciting new services and applications. For example, the key 2G application was voice. 3G brought data services to the market, enabling e-mail and web browsing. 4G applications are still being defined but may include things like streaming video.

Q: Where are we with 3G and the shift to new standards for 4G networks?

A: Major US wireless networks are using 3G specifications, providing users with a noticeable improvement in data speed. 3G allows simultaneous use of voice and data transfers. The speed of a smartphone browser, and the ability to send and receive pictures and larger files, are significant 3G enhancements.

While 4G offers even more capability, there are different approaches to 4G standards. Whenever there are new generations of wireless standards, differing innovations are developed and tend to find their own audiences over time.

The major 4G standards are Long Term Evolution (LTE) and WiMAX (also known as 802.16m). LTE commitments are the logical extension for organizations whose current systems are UMTS / 3GPP based. LTE is favored by organizations that hold paired frequency spectrum allocations. WiMAX commitments tend to come from organizations that hold unpaired frequency spectrum allocations, although there is significant interest in the time division duplex version of LTE (TD-LTE) here as well.

Regardless of which standard eventually prevails, TriQuint will support new generations of systems to assist all developers as they work towards continuous improvement.

We do this while looking ahead of the current trends in the evolution of wireless.

Q: What exactly are the improvements that make each new Generation?

A: Generation changes in wireless communications generally have to do with both the data rate and architecture of the system infrastructure. It is safe to say that each new generation enables higher data rates, lower latency and new applications relative to the previous one.

One major change is that 4G systems use a packet infrastructure rather than traditional telephone architecture. Since 4G is relatively new, it will still take time for the full extension of the improvements to present themselves.

Q: With the acceptance of 3G and 4G, is the 2G system obsolete?

A: While 2G systems have been surpassed by new generations of wireless, the system remains viable and has a large user base in areas where 3G and 4G systems have not been deployed. It will continue to be important for several years into the future. At some point, it is likely that the 2G spectrum will be refarmed to support newer generations of wireless services.

Q: What are WiMAX, WiFi and LTE technologies? How do they fit into the 4G network?

A: LTE is a cellular communications protocol for 4G networks. LTE is favored by organizations that hold paired frequency spectrum allocations and especially those whose current systems are UMTS / 3GPP based. There is also growing interest in the time domain version of LTE – TD-LTE – for use in unpaired spectrum.

WiMAX is also a communications protocol for 4G networks It is also known as 802.16m and tends to be favored by organizations that hold unpaired frequency allocations.

WiFi is a short-range communications protocol popular for consumer devices and also a familiar term with broad audience recognition. WiFi is best viewed as a supporting protocol that works in conjunction with LTE or WiMAX devices rather than as a competitive technology.

Comparisons and confusion between LTE, WiMAX and WiFi are frequent because all are related to the ability to wirelessly connect and provide Internet access. WiFi generally operates in a home or office building to connect computers, smartphones and other wireless devices.

Q: What are the major design considerations for 4G systems?

A: The most significant changes are new frequency bands that have been opened to support the 4G services. The most well known examples are in the “Digital Dividend” bands where former analog TV channels have been refarmed for 4G services. Other changes are wider bandwidths, more complex modulation and the usage of spatial diversity (MIMO) to improve data rates.

Q: What can we expect in future 5G or 6G systems?

A: The main goals for new generations of wireless service will surely include the ability to handle massive amounts of information without any delay.

Communications will be clearer as they become increasingly error free and reliable no matter where you are. New generations of wireless will have the ability to sort through, identify, send and receive wireless transmissions on ever more crowded airways.

Safety and security, always a concern, will be built deeper into the systems to protect information, provide privacy and integrate all aspects of wireless. Astonishing new applications are always on the horizon. These will need new generations of wireless capabilities that TriQuint research is dedicated to help design and build.