FTTxtra » LTE

Long Term Evolution-Advanced (LTE-Advanced)

John Bartell — Fri, 11 Sep 2009 21:59:15 +0000

Long Term Evolution-Advanced (LTE-Advanced) is a mobile wireless broadband standard (for some background and context, read my overview of wireless broadband) designed to meet the ITU’s requirements for 4G wireless broadband. 4G describes wireless networks that comply with IMT-Advanced requirements as detailed in ITU-R report M.2134.

4G is defined as a high bandwidth (>100 Mbps), spectrally efficient wireless broadband technology handling only IP packets for voice and data services. 4G networks are interoperable with other wireless networks, and they provide the Quality of Service required to deliver the whole range of broadband Internet technologies, including real-time services like interactive audio and video.

The IEEE is developing standards for WiMAX-m, which is an alternative 4G wireless broadband technology quite similar to LTE-Advanced. One difference is that LTE-Advanced terminals are expected to be substantially more energy efficient for uplink transmissions (because LTE-Advanced’s SC-FDMA uplink transmitters use much less transmit power than SOFDMA transmitters, which are used for WiMAX-m uplinks) allowing smaller batteries and/or longer battery life in LTE-Advanced mobile terminals.

3GPP’s take on 4G, LTE-Advanced is part of its Release 10, which is planned for release in early 2011. Work on Release 10 and LTE-Advanced did not begin until early 2008. 3GPP’s progression of wireless broadband standards, mapped to the ITU 2G, 3G, and 4G requirements, is given in the diagram below (from 3GPP).

LTE-Advanced will use spectrum in 20 Mhz chunks allocated in what is called carrier aggregation up to a total of 100 Mhz (5 component carriers) used for transmission in each direction. 100 Mhz is a lot of spectrum, especially in a Frequency Division Multiplexed (FDD) system which has separate spectrum for the uplink and the downlink (requires a total of 200 Mhz). In reality, the uplink spectrum allocation is likely to be much lower than the downlink allocation. If 100 Mhz is assigned to the downlink, the uplink may have perhaps only 20 Mhz. These asymmetric FDD assignments will conserve spectrum and are a good fit for the typically asymmetric bandwidth utilization by broadband subscribers.

LTE-Advanced can achieve a max downlink rate of 1 Gbps with as little as 40 Mhz (two 20 Mhz allocations) of assigned spectrum. Peak uplink rate for LTE-Advanced is expected to be 500 Mbps. LTE-Advanced will provide somewhat higher rates to fixed subscribers than to mobile subscribers. Like LTE, LTE-Advanced uses OFDMA for the downlink, SC-FDMA for the uplink, and MIMO to achieve its high rates. Beyond just the higher peak rate, LTE-Advanced will provide broadband data rates over a larger area than is possible with LTE.

As the successor to LTE, LTE-Advanced will be backward and forward compatible with LTE, which means LTE terminals will work in LTE-Advanced networks (this is why LTE-Advanced uses spectrum in 20 Mhz chunks), and LTE-Advanced terminals will work in LTE networks. Each component carrier of the LTE-Advanced spectrum will appear as an LTE carrier to LTE terminals. Initial LTE deployments are expected in late 2009 and early 2010. Initial LTE-Advanced deployments are expected perhaps three years later.

If you want even more detail on LTE-Advanced, including some simulation data, read this article from Ericsson Research (only 5 pages, moderately technical, just one equation). And, if you really want the whole story on mobile data, then this brand new 118-page article (not very technical) from Rysavy Research entitled HSPA to LTE-Advanced is for you.

And finally, here is a video about how folks might use LTE.

[youtube xQDGH9JzZtA]

Long Term Evolution (LTE) Overview

John Bartell — Tue, 08 Sep 2009 12:06:57 +0000

LTE (Long Term Evolution) is a form of broadband wireless access standardized by the 3GPP, which is a global collaboration of telecommunication associations that work on broadband wireless internet standards under the authority of the ITU. Like WiMAX, which is a competitive technology defined by the IEEE, LTE can serve both fixed and mobile (moving) subscribers. When they serve mobile subscribers, LTE and WiMAX are considered 4G wireless data technologies.

LTE is defined in Release 8 of the 3GPP standards (finalized January 2009), and work on the LTE standard began in 2004. LTE-Advanced is a higher speed version of LTE and will be part of 3GPP’s Release 10. These new WiMAX and LTE technologies will provide pressure on Telcos and MSOs to deploy ever higher DSL, DOCSIS, and FTTH data rates in the markets served by these high bandwidth wireless data technologies.

Since data traffic dominates voice traffic today (on both wireless and wireline networks), all traffic on LTE is transported as data packets. A primary goal for LTE is delivery of high data throughput, and aggregate data rates well over 100 Mbps are possible with LTE systems (1 Gbps with LTE-Advanced). Coupled with LTE’s high data throughput is its low latency, which is generally less than 10 ms.

The high bandwidth and low latency of LTE networks make it well suited to modern Internet applications requiring high throughput and interactivity (for example video over Skype). Initially, LTE will be all about broadband data, and the first expected subscriber products are USB dongles (an early version is shown in the video at the end of this article). Ultimately, LTE USB adaptors should look like this Motorola one shown below, and eventually LTE will be integrated into NetBooks and Laptops.

Highly flexible, LTE can serve both fixed and mobile subscribers. When it serves fixed subscribers, LTE competes with DSL, HFC DOCSIS, and FTTH, though it is never likely to be able to deliver the same levels of dedicated bandwidth owing to its shared architecture. When it serves mobile subscribers, LTE displaces the various 3G technologies like EDGE, UMTS, and CDMA2000. LTE systems may support one of two different modes for mobility: optimized, which supports users to about 10 miles/hr (walking and jogging I suppose), and high-performance, which supports users moving up to about 75 miles/hour (surfing the web between toll booths on the Garden State Parkway, as a passenger of course).

LTE provides scalable spectrum options with 1.4, 3, 5, 10, 15, and 20 Mhz assignments possible. Maximum peak data rates are achieved with the highest spectrum allocations, of course. With 20 Mhz of spectrum, the maximum downstream peak data rate is 326 Mbps using 4×4 MIMO (4 transmit and 4 receive antennas, Multiple Input Multiple Output). 86 Mbps is the maximum uplink peak data rate using 64 QAM on 20 Mhz.

ABI Research is predicting that wireless carriers will spend $8.6B on LTE by 2013, and over 32 million subscribers will be using the services. Some of the world’s largest wireless carriers, including AT&T, China Mobile, Verizon Wireless, and Vodaphone, are all planning to deploy LTE networks. However, AT&T is not in any rush as they believe HSPA release 7 will take them to 20 Mbps sometime in 2009.

The video below shows some demonstrations of Long Term Evolution technology at Mobile World Congress 2009 in Barcelona, Spain.

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And, if you want to see how LTE might be used, watch the really interesting video (almost SciFi) below.

[youtube xQDGH9JzZtA]

Broadband Wireless Overview

John Bartell — Sun, 06 Sep 2009 13:52:39 +0000

Broadband wireless Internet access is simply the delivery of broadband Internet rates over a wireless connection. Especially popular for rural areas, broadband wireless competes with fiber, DSL, and HFC.

As defined in my article on broadband Internet, broadband is a persistent connection at rates of about 200 kbps or higher, and two important broadband wireless technologies for providing these rates are WiMAX and LTE. Older technologies used by wireless broadband Internet providers include LMDS, MMDS, Free Space Optics (FSO), satellite, and point-to-point microwave links. Both WiMAX and LTE provide rates that likely require fiber uplinks to the towers, hence the new term Fiber to the Tower or FTTT.

WiMAX

WiMAX (Worldwide Interoperability for Microwave Access) broadband is a form of broadband wireless Internet access that is standardized by the IEEE and currently capable of rates of up to 15 Mbps or more, though typical wireless internet service rates are a few Mbps. WiMAX technology has been a popular method of delivering broadband wireless access to rural areas owing to its ability to serve a large geographic area with relatively modest investments compared to DSL, fiber, and HFC.

The IEEE is working on a new version of WiMAX known as 802.16m or WiMAX-m that provides for access rates of up to 1 Gbps. The IEEE 802.16m working group has produced this Draft IEEE 802.16m System Description Document, which provides an overview of where the WiMAX broadband wireless standard is going. The IEEE 802.16m WiMAX standard will specify multiple carriers to increases the bandwidth available to a subscriber. The WiMAX Forum is dedicated to increasing the acceptance of WiMAX networks by wireless broadband providers and WiMAX broadband service by subscribers.

LTE

LTE (Long Term Evolution) is another form of broadband wireless access and a competitor to the new WiMAX 802.16m standard for attention by wireless internet service providers. LTE is being standardized by the 3GPP (3rd Generation Partnership Project), which is a global collaboration of telecommunication associations that work on broadband wireless internet standards under the aegis of the ITU. Release 8 of the 3GPP standards (frozen December 2008) defines LTE and provides an all-IP network, data rates well over 100 Mbps, and low latency (generally less than 10 ms).

LTE-Advanced is the successor to LTE and provides peak data rates as high as 1 Gbps. Work on LTE-Advanced is underway by 3GPP, and will be part of 3GPP’s Release 10, which is still in development. The evolution to LTE-Advanced is shown in 3GPP’s evolution chart below.