TDD System for 3G and B3G Dr. W.C.Y. Lee, Chairman LinkAir Communications Santa Clara, CA 3GPP2 Vision JEM San Diego, CA July 12-13, 2002

FCC Spectrum Policy Task Force The Spectrum Policy Task Force’s tentative work plan for this inquiry is as follows: The Spectrum Policy Task Force’s tentative work plan for this inquiry is as follows: – Public Notice seeking comment on spectrum policy, issued June 6, – Comments filed by July 8, – Reply comments filed by July 23, – Multiple workshops conducted by the Spectrum Policy Task Force to facilitate debate regarding spectrum policies. July 2002 to August – Spectrum Policy Task Force provides report to Commission by October 2002.

TDD: Next Generation Wireless TDD has significant benefits for cellular networks: TDD has significant benefits for cellular networks: –Additional spectral efficiency, especially for Internet and data traffic –Simpler designs –Cheaper spectrum in Asia and Europe, potentially the US –High potential for Next Generation (e.g. 3G and B3G) However, current TDD has severe limitations: However, current TDD has severe limitations: –Mainly caused by strong other-cell interference issues –Low or no mobility, pico-cell deployments – cannot replace existing cellular systems –PHS, TDS-CDMA –Some broadband fixed wireless solutions Breakthrough technology is required Breakthrough technology is required

Clarity (quality) Coverage Capacity – spectrum efficiency *Do not need to consider the cost at the beginning. *Bell System’s products should last at least 40 years as a designing guideline in 1960s. What factors make a Wireless Communication System successful? A 3C Principle

How a good new Wireless Communication System can Survive The theory of the technology should be sound – high spectrally efficient system. The theory of the technology should be sound – high spectrally efficient system. The manufacturing product should be carefully designed. The manufacturing product should be carefully designed. The system providers should be working hand-in-hand with the vendors during the deployment of a new system. The system providers should be working hand-in-hand with the vendors during the deployment of a new system.

The effective approach to increase radio capacity and/or the transmission rate in the wireless environment is to reduce the interference. The tough game to play is reducing interference in wireless communications. Many existing technologies have been added together to reduce the interference in FDD systems. Reducing Interference is the Key

None of them can be used solely in FDD systems. Very undesirable to use TDD in a large area cellular system in the past because of its interference. A set of smart codes can reduce interference very effectively, and be applied to a TDD system. Reducing Interference is the Key (cont’d)

CDMA – Code Division Multiple Access Code: It can be any code. Code: It can be any code. Today: C is using Walsh Code which is not quite smart. Today: C is using Walsh Code which is not quite smart. A set of smart codes can be used to reduce interference for CDMA. A set of smart codes can be used to reduce interference for CDMA.

Description of Smart Codes A set of smart codes can be found – –Auto-correlation – –Cross-correlation No multi-path interference No multi-user interference

A Most Spectrum Efficient Duplexing System - CDD TDD + Smart Codes = CDD TDD + Smart Codes = CDD CDD (Code Division Duplexing) system can eliminate essentially all the interference and be an ideal system for CDMA scheme. CDD (Code Division Duplexing) system can eliminate essentially all the interference and be an ideal system for CDMA scheme. C 1, C 2 have to be a set of smart codes. f1,C1f1,C1 Adjacent BaseHome Base, f1,C1f1,C1 f2,C2f2,C2 f1,C2f1,C2

CDD Has Never Existed The choices of effectively reducing interference in wireless communications The choices of effectively reducing interference in wireless communications –Multiple Access Schemes FDMA (Frequency Division Multiple Access) f 1, f 2, f 3, f 4 ……FDMA (Frequency Division Multiple Access) f 1, f 2, f 3, f 4 …… TDMA (Time Division Multiple Access) t 1, t 2, t 3, t 4 ……TDMA (Time Division Multiple Access) t 1, t 2, t 3, t 4 …… CDMA (Code Division Multiple Access) C 1, C 2, C 3, C 4 ……CDMA (Code Division Multiple Access) C 1, C 2, C 3, C 4 …… –Duplexing Systems FDD (Frequency Division Duplexing)FDD (Frequency Division Duplexing) TDD (Time Division Duplexing)TDD (Time Division Duplexing) CDD (Code Division Duplexing) ?CDD (Code Division Duplexing) ?

Capacities of FDD and CDD FDD System FDD System The received signal at a mobile among M mobiles in an interference-limited environment. M = Where: E b = energy per bit R = bit rate (bit/sec.) B = bandwidth in Hz I = interference power I o = power/Hertz I a = adjacent cell interference M = number of mobiles

Capacities of FDD and CDD (cont’d) CDD System CDD System CDD system is operated in a noise- limited environment Thus: I a O, I o N o M’ = M’ is the number of mobiles

TDD/CDD Any single spectrum band with a bandwidth equal to, or greater than 1.6 MHz, can be considered for the TDD/CDD application. The System R&D cost is relatively low. The handset cost can be lower. Since no duplexer is needed, the size of the handset is smaller. Power consumption is lower. The ideal system for an asymmetrical traffic condition. TDD has the highest spectral efficiency. TDD can be the New 3G or B3G system.

The Milestones of Wireless Communications Before 1989—cell reuse (FDMA & TDMA were used) Down-link cell reuse plan Up-link cell reuse plan After 1989-CDMA was a breakthrough technology Down-link cell reuse plan Up-link cell reuse plan After 2000—LAS is another breakthrough technology Both down-link and up-link cell reuse plans are f1f1f1f1 f2f2f2f2 f3f3f3f3 f4f4f4f4 f1f1f1f1 f2f2f2f2 f1’f1’f1’f1’ f2’f2’f2’f2’ f3’f3’f3’f3’ f4’f4’f4’f4’ f1’f1’f1’f1’ f2’f2’f2’f2’ f1f1f1f1 f1f1f1f1 f1f1f1f1 f1f1f1f1 f1f1f1f1 f1f1f1f1 f1’f1’f1’f1’ f1’f1’f1’f1’ f1’f1’f1’f1’ f1’f1’f1’f1’ f1’f1’f1’f1’ f1’f1’f1’f1’ f1f1f1f1 f1f1f1f1 f1f1f1f1 f1f1f1f1 f1f1f1f1 f1f1f1f1 FDD Systems TDD/CDD System

After 1980  From a single-cell system to a multiple-cell system. After 1989  From frequency reuse concept to one-frequency concept After 2000  From interference limited environment to noise limited environment. The Revolutionary Concepts for High-Capacity Wireless Mobile

Summary CDMA is the best multiple access scheme compared to all others for combating interference. CDMA can choose more than one code. A smart code can make a CDMA system very effective. A set of smart codes used in TDD becomes CDD. TDD/CDD is a B3G technology. A TDD/CDD system is simpler, lower cost.

Suggestion Need a TSG-TDD in 3GPP2. Need a TSG-TDD in 3GPP2. Study many enabling technologies for TDD. Study many enabling technologies for TDD. Support the goal of FCC’s Spectrum Policy Task Force formed 6/6/02. Support the goal of FCC’s Spectrum Policy Task Force formed 6/6/02.