4G Wireless Technology

Airspan Technical Symposium

May 3, 2010By Donn Swedenburg

and Mark T. Pflum

RVW, Inc.(402)564-2876

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©2009 RVW, Inc.

TOPICS• 4G Wireless Definition

• Technologies used in 4G

• Pre-4G

• Real World Implications

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4G Wireless

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• 4G Wireless: – Defined by the ITU (International

Telecommunication Union).– A 4G system targets peak data rates of

approximately 100 Mbps for high mobility service.

– A 4G system targets peak data rates of approximately 1 Gbps for low mobility/ fixed service.

– Shall support required channel bandwidthsfrom 5 to 20 MHz with an optional 40 MHz channel allowed.

4G Wireless: Definition

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– Shall support both TDD and FDD duplexing technologies with UL/DL configurable ratiosfor both.

– Network architecture will be all IP based.– Must utilize MIMO technology. – Latency:

• Data - 10 ms. In both UL & DL• Idle state to active state – 100 ms.• Site handoff – 50 ms. Intrafrequency, 150 ms.

Interfrequency.

4G Wireless: Definition

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• MIMO - Minimum antenna configurations.– For the BS - a minimum of 2 Tx and 2 Rcv antennas– For the MS - a minimum of 1 Tx and 2 Rcv antennas

• MIMO Techniques -– Beam forming – makes use of multiple antennas to

steer or focus signal in a particular direction. Can reduce adjacent site self-interference & add reach.

– SU-MIMO (Single User MIMO)• Transmitting parallel & unique data streams in

the same frequency-time resource to a single user. (Spatial Multiplexing)

• Improves individual users throughput.

4G Wireless: Technologies used in 4G

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4G Wireless: Technologies used in 4G

• MIMO Techniques - continued– MU-MIMO (Multiple User MIMO)

• Transmitting parallel & unique data streams in the same frequency-time to multiple users. (Spatial multiplexing)

• Improves sector/site capacity throughput.

– STBC - Space Time Block Coding• The simplest of the STBCs transmits

multiple copies of a single data stream across a number of antennas which improves the SNR of the received data to improve the reliability of data-transfer.

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• OFDMA – Orthogonal Frequency Division Multiple Access. (LTE DL only, WiMAX UL and DL).

• Two types of sub-carrier permutations.– Contiguous subcarriers grouped into logical

sub-channels (Used in LTE & WiMAX sub channels).

– Pseudo-random subcarriers grouped into logical sub channels (Used in WiMAX FUSC andPUSC).

4G Wireless: Technologies used in 4G

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• SC-FDMA – Single Carrier Frequency Division Multiple Access. (LTE UL only)– Low peak-to-average power ratio conserves

mobile battery life.

4G Wireless: Technologies used in 4G

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• ACM – Adaptive Coding and Modulation– Changing the coding (1/2, 2/3, 3/4) and

modulation schemes (BPSK, QPSK, 16 QAM, 64QAM) based upon current RF conditions.

• HARQ - Hybrid automatic repeat request – The most common version uses transmissions

with incrementally more redundant error-detecting codes such as cyclical redundancy checking (CRC) and forward error correction bits (FEC).

4G Wireless: Technologies used in 4G

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4 G Wireless: Pre 4G – LTE• LTE capable of 100 Mbps in DL and

50 Mbps in UL.– This would be for a single user, single

site/sector with 20 MHz bandwidth for both uplink and downlink under extremely favorable RF conditions with adequate backhaul capacity.

• Key Features of LTE– Multiple access scheme – DL is OFDMA, UL is

SC-FDMA.– Adaptive modulation. coding, H-ARQ and error

correction.– Advanced MIMO (2 X 2, 4 X 4) spatial, single or

multi-user multiplexing techniques– Support for both FDD and TDD

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4 G Wireless: Pre 4G – LTE• Initial LTE deployment by Verizon

will not technically meet the 4G requirement as stated by the ITU

Reference: http://business.motorola.com/experiencelte/lte-depth.html

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• 802.16-2004 (d) is often called Fixed WiMAX– Fixed WiMAX does not support Mobility.– Does not support 1 cell frequency reuse.– Utilizes OFDM-256 FFT (Orthogonal

Frequency-Division Multiple) – Also supports OFDMA 2048, but only

OFDM 256 FFT is specified in WiMAX 802.16d profiles.

– Supports both TDD (Time Division Duplexing) and FDD (Frequency Division Duplexing) services

4G Wireless: Pre 4G - WiMAX

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4G Wireless: Pre 4G – WiMAX “d”• 802.16-2004 – Fixed WiMAX

– Fixed WiMAX throughputs for OFDM-256 (Unknown SNR)

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4G Wireless: Pre 4G – WiMAX “e”• 802.16-2005

– Mobile WiMAX – Not backwards compatible with Fixed WiMAX

– Offers the capability of 1 cell frequency reuse.– Supports TDD, FDD, and Half-Duplex FDD

operation– However the initial release of Mobile WiMAX

certification profiles will only include TDD.– Sprint/Clearwire are referring to 802.16 “d” and “e”

as 4G which is not technically correct.

http://www.nextel.com/en/solutions/mobile_broadband/mobile_broadband_4G.shtml

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4G Wireless: Pre 4G – WiMAX “e”• 802.16-2005 – Theoretical Throughputs

The highlighted values indicate data rates for optional 64QAM in the UL.

Reference: “Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation” WiMAX Forum

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4G Wireless: Implications• So, where are we on the 4G Timeline?

– February, 2007 - NTT tests a 4G lab prototype. Achieves 100 Mbps mobile & 1 Gbps fixed with 4 X 4 MIMO. Achieves 5 Gbps DL with a 100 MHz channel and a 12 X 12 MIMO.

– May, 2007 – IEEE proposes 802.16m, upgrade to the 802.16e standard.

– April, 2008 – LG/Nortel demonstrates the e-UTRA LTE SDR at 50 Mbps mobile at 68 MPH.

– December, 2009 – First commercial LTE deployment in Stockholm, Sweden. Single user tests show 42.8 Mbps down, 5.3 Mbps up.

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4G Wireless: Implications• While 4G will undoubtedly be a future

force, be aware that -– Real 4G does not exist today– Real 4G will require access to huge amounts of

last-mile spectrum that is not available today.– Equipment R&D still in progress.– Backhaul networks already under stress from

“3G” networks will need continuing capacity upgrades

• High capacity ethernet connections over fiber optic networks will probably be the needed at all sites in the near future.

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Succeeding With Teamwork!