ODMA Opportunity Driven Multiple Access Raul Bruzzone Opportunity

ODMA Opportunity Driven Multiple Access Raul Bruzzone

Opportunity Driven Multiple Access (ODMA) Introduction • ODMA is a Multiple Access technique that makes part of the UMTS Terrestrial Radio Access concept. • It is based on the use of Intelligent Radio Repeaters (also called “relays”). • Repeaters communicate with the Mobile Units, and between them, using the TDD mode. • Repeaters communicate with the Base Station using the FDD mode. • ODMA provides increasing radio capacity to cells located in Urban environments. December 20 Raul Bruzzone 2

PATH DIVERSITY • In a Urban Environment, several radio paths co-exist between the UE and BS. • Significant variations in path attenuation may be expected. • If a Repeater is introduced in the radio path (Z), the power budget may be reduced in excess of 30 d. B. • As the transmission power is reduced, interference to adjacent cell also diminishes. • This interference reduction may be traded as increased Cell Traffic Capacity. December 20 ODMA 1 X X X Z Y Repeater 3

Urban Environment Model 250 m M S M S S S S 250 m M M S S BTS S S M M S S S 100 Traffic Channels available for each Cell M S M: S: BTS: Node: December 20 S Mobile - an ODMA mobile communicator (e. g. phone) Seed - a Mobile which is fixed in position and continually powered Base Station - a gateway to a fixed communications link - any of above ODMA 2 4

System Performance Free-space Model (Attenuation = k*d-2) -60. 00 -65. 00 --60. 00 -80 --70 -70. 00 --65. 00 -70. 00 -75. 00 --70. 00 -80. 00 --75. 00 -85. 00 --80. 00 -75. 00 -70 -90 --80 -100 --90 -110 --100 -120 --110 -80. 00 -120 -85. 00 Total Power at Repeaters (Relaying System) Transmitted Power at Mobiles (Non-relaying System) Repeaters near the Base Station operate at higher power than those located in the periphery of the cell December 20 Mobiles far from the Base Station operate at higher power than those located in the centre of the cell ODMA 2 5

System Performance Urban Model (Attenuation = k*d-4 ) -30 --20 -30. 00 -40 --30 -50 --40 -35. 00 --30. 00 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -40. 00 --35. 00 -40. 00 -45. 00 --40. 00 -50. 00 --45. 00 -55. 00 --50. 00 -60 --50 -70 --60 -80 --70 -90 --80 -100 --90 -110 --100 -50. 00 -55. 00 Total Power at Repeaters (Relaying System) Transmitted Power at Mobiles (Non-relaying System) Repeaters near the Base Station operate at higher power than those located in the periphery of the cell December 20 Mobiles far from the Base Station operate at higher power than those located in the centre of the cell ODMA 2 6

Conclusion: • A system based on Repeaters produce less co-channel interference on neighbouring cells, than other system that is only based on UE directly radiating to the Base Station. December 20 ODMA 2 7

Number of Calls per Cell Manhattan Grid Model 30 With Repeaters 25 Without Repeaters 20 15 10 5 0 2 December 20 ODMA 2 8

Required Transmission Power per Link Manhattan Grid Model -10 d. Bm With Repeaters Linear Scale Without Repeaters -36 d. Bm 0 December 20 ODMA 2 9

Total Transmission Power per Cell Manhattan Grid Model -7 d. Bm Linear Scale With Repeaters Without Repeaters -21 d. Bm 0 December 20 ODMA 2 10

TDD Frame Structure for ODMA Operation 10 ms 4. 096 Mchip/s 625 ms Relay Link ORACH Slot ODCH Slot ORACH: ODMA Random Access Channel ODCH: ODMA Dedicated Channel December 20 ODMA 3 11

Opportunity Driven Multiple Access (ODMA) Summary • In Urban environments, the infrastructure required to support given levels of coverage and capacity could be very significantly cheaper with ODMA than with a more traditional approach. • The mean transmission power can be reduced by up to 30 d. B. • More efficient frequency re-use. • Variation of the locations of peak demand can be supported more efficiently, without having to supply capacity which is unused for most of the day. Similarly, high bandwidth on demand can be supplied efficiently. • Mixed bathing — i. e. multiple operators in the same cell — can be supported without the need for dividing spectrum between operators. • ODMA allows greater resilience to Base Station failure. December 20 ODMA 2 12

ODMA References ODMA 1 ODMA (E 20/97) K. Mayes, J. Larsen (Vodaphone) ETSI UMTS Workshop. Sophia Antipolis. December 1996. ODMA 2 Characteristics of Opportunity Driven Multiple Access (E 21/97) Vodafone Ltd, Salbu R&D Ltd. TDOC SMG 2 UMTS 30/97. March 1997 ODMA 3 Physical channels and mapping of transport channels onto physical channels (TDD) S 1. 21 V 2. 00 UMTS Specification Document 3 GPP. April 1999 December 20 Raul Bruzzone 13

coming next. . . Introduction to cdma 2000 December 20 Raul Bruzzone 14