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Next-Generation Wireless: LTE & WiMAX

    by Douglas Dixon

LTE -- Long Term Evolution
WiMAX -- Worldwide Interoperability for Microwave Access


See also: WINLAB Looks to the Wireless Future

We've become rather jaded to the spread of wireless technology, with cell phones that roam the world, Bluetooth headphones, and ubiquitous Wi-Fi Internet hotspots.

But that's just the beginning -- and the focus is now on the challenges of the future of ubiquitous wireless networking with high-speed mobile Internet access, as outlined by Dipankar Raychaudhuri, director of WINLAB and professor of electrical and computer engineering at Rutgers University, at his keynote presentation at the recent IEEE Sarnoff Symposium held in April at the Nassau Inn in Princeton.

Raychaudhuri began his presentation by highlighting the astounding growth of wireless devices: Today there are some 2.5 billion cell phones (500 million with Internet service), 100 million mobile computers, and 600 million Internet-connected PCs worldwide, and growing rapidly. By 2010, he sees over billion wireless Internet devices (cell phones, PDAs, laptops, and sensors). In particular, as small wireless sensor devices begin to be deployed, some estimates expect 5 to 10 billion units by 2015.

This was the key issue addressed at the Sarnoff Symposium -- the need to be ready to deliver high-speed Internet connectivity (including streaming video) to every mobile wireless device, around the beginning of the next decade.

LTE -- Long Term Evolution

The challenge were echoed by speakers from the major cellular carriers, including a keynote presentation from Richard Lynch, executive vice president and chief technology officer at Verizon Communications. To face this issue, Lynch has assumed responsibility across all of the Verizon business units for technology direction and network planning, including phone, Internet, and mobile.


Verizon, along with other major international cellular carriers, is planning to deploy LTE (Long Term Evolution) as its fourth generation ("4G") mobile broadband network technology ( 

Lynch's vision is to move away from the current combination of different phone and data networks, and start over with a clean slate of a global IP (Internet Protocol) network designed from the ground up as an Internet backbone for digital data. He sees the need to be able to deliver content anywhere, at any time, on any screen.

Lynch sees LTE delivering 10 to 20 Mbps to individual users when deployed in the latter half of 2010, with the potential to support 40 to 100 Mbps. This is the equivalent of delivering the full bandwidth of today's high-end Verizon FIOS hard-wired fiber optics service to the home -- with its high-speed Internet and hundreds of high-definition TV channels -- but direct to a wireless mobile device. 

Lynch sees the higher speeds as a requirement for meeting the expected demand, for applications including streaming high-quality video, virtual reality teleconferencing, and, in general, 24/7 connectivity and collaboration.

WiMAX -- Worldwide Interoperability for Microwave Access

An alternate view of next-generation wireless comes from the WiMAX Forum , which has developed the WiMAX (Worldwide Interoperability for Microwave Access) wireless standard to provide high-speed broadband connectivity across long distances ( 


Mobile WiMAX, approved on 2005 (technically IEEE 802.16e-2005), is designed to support high-speed mobile Internet access for data-intensive applications such as Internet audio and video, high-definition video, voice over internet (VoIP) telephone and Internet television (IPTV).

The WiMAX Forum projects broadband access speeds for downloads ranging from 1 to 5 Mbps, depending on factors including which frequency is being used, the distance of the user from the base station or node, whether there is line of site to the base station, and the number of users on the network (with a typical cell radius of three to ten kilometers).

These is also the potential to burst to higher speeds. WiMAX is designed to support a total system capacity of up to 40 Mbps per channel (across multiple users), or up to 15 Mbps for mobile networks within a typical cell radius of up to three kilometers.

Two key technologies are incorporated into the Mobile WiMAX standard to increase data throughput and/or signal coverage:

  • Orthogonal Frequency Division Multiple Access (OFDMA) supports more simultaneous users by increasing spectral efficiency. It breaks a signal into many independent pieces before transmitting it across the airwaves. By diversifying the signal, it can be reconstructed at the other end even if some of the pieces are not received.
  • Multiple Input/Multiple Output (MIMO) smart antenna technology uses multiple antennas at both ends of the wireless connection to carry more data traffic and Increase throughput and range. MIMO is particularly beneficial in high interference environments like cities.

WiMAX and Wi-Fi are complementary technologies. WiMAX can fill in gaps between Wi-Fi hotspots, extending your wireless reach on the go.

The WiMAX future in the U.S. was clarified in May 2008 with the announcement of a merger of Clearwire, founded by cellular pioneer Craig McCaw, and Sprint's Xohm wireless broadband business, supported by a $3.2 billion investment by five major WiMAX enthusiasts -- Intel, Google, Comcast, Time Warner Cable, and Bright House Networks -- with plans to deploy the first nationwide mobile WiMAX network (

With embedded WiMAX chipsets coming in laptops, phones, PDAs, mobile Internet devices, and consumer electronic equipment, mobile WiMAX technology is expected to support applications such as live videoconferencing, recorded video, games, and the transfer of large data files.


Verizon Wireless - LTE press release

Wikipedia - LTE

WiMAX Forum

WiMAX Forum - FAQ

Intel - WiMAX technology

Intel - WiMAX press release


Clearwire - WIMAX presentation

Wikipedia - WiMAX

Portions originally published in the U.S.1 Newspaper, June 11, 2008