APAN 2005, , July 2005Ng Chee Kyun1 A Realistic Reverse Link Capacity Improvement with A Joint Multiple Access of CDMA and SDMA Systems using Smart Antenna Ng Chee Kyun Borhanuddin Mohd Ali Sabira Khatun Sudhanshu Shekhar Jamuar Mahamod Ismail

APAN 2005, , July 2005Ng Chee Kyun2 Presentation Outline Introduction Cellular System Capacity CDMA Capacity SDMA Capacity Joint Multiple Access (CDMA and SDMA) System Joint Multiple Access System Reverse Link Capacity Concluding Remarks

APAN 2005, , July 2005Ng Chee Kyun3 Digital Radio Communication Systems Frequency Division Multiple Access (FDMA) ~ 1 st Generation Time Division Multiple Access (TDMA) ~ 2 nd Generation Code Division Multiple Access (CDMA) ~ 3 rd Generation (3G)

APAN 2005, , July 2005Ng Chee Kyun4 Space Division Multiple Access (SDMA)

APAN 2005, , July 2005Ng Chee Kyun5 Cellular System Capacity Narrowband radio systems (TDMA and FDMA) - dimension or bandwidth limited. Spread spectrum system (CDMA) - interference limited. - Traditional CDMA systems are all self-interference systems. Spatial diversity system (SDMA) - interference limited. Any attempt to reduce interference will convert directly and linearly into increased capacity.

APAN 2005, , July 2005Ng Chee Kyun6 CDMA Capacity (Source of Interferences) Intra-cell interference. Inter-cell interference. BS 0

APAN 2005, , July 2005Ng Chee Kyun7 Power Control To avoid near far effect - The base station receives all mobile stations at the same power level, S. Signal to interference ratio (SIR)

APAN 2005, , July 2005Ng Chee Kyun8 Intra-Cell Interference W = Spreading rate (chip per second) R = Bit rate (bit per second) W/R = Processing gain (PG) System Capacity: Assume that a minimum of 5 (7 dB) is required to achieve bit error rate (BER) of [Gilhousen 91]

APAN 2005, , July 2005Ng Chee Kyun9 Inter-Cell Interference = power of distance = shadowing loss Propagation Model: Path-loss, PL Frequency Reuse Pattern in CDMA Total inter-cell interference

APAN 2005, , July 2005Ng Chee Kyun10 SDMA Capacity Smart Antenna – Generates high directive narrow beam. System capacity Number of nulls Co-channel and side-lobes interferences

APAN 2005, , July 2005Ng Chee Kyun11 Smart Antenna Radiation pattern = Phase shift = Angle of arrival n = Number of antenna elements

APAN 2005, , July 2005Ng Chee Kyun12 Smart Antenna Beamwidth Sizes

APAN 2005, , July 2005Ng Chee Kyun13 Smart Antenna with 8 antenna elements

APAN 2005, , July 2005Ng Chee Kyun14 Smart Antenna with 32 antenna elements

APAN 2005, , July 2005Ng Chee Kyun15 Joint Multiple Access (CDMA and SDMA) System A.F. Naguib, A. Paulraj and T. Kailath, Capacity Improvement with Base-Station Antenna Arrays in Cellular CDMA, IEEE Transactions on Vehicular Technology, vol. 43, no. 3, pp. 691 – 698, Aug E. Buracchini, F. Muratore, V. Palestini and M. Sinibaldi, Performance Analysis of A Mobile System Based on Combined SDMA/CDMA Access Technique, IEEE 4th International Symposium on Spread Spectrum Techniques and Applications Proceedings, vol. 1, pp. 370 – 374, Sept B. Ng and E.S. Sousa, Performance Enhancement of DS-CDMA System for Wireless Local Loop, IEEE International Telecommunications Symposium (ITS) Proceedings, vol.1, pp. 78 – 82, 9-13 Aug J. Yu, Y.D. Yao and J. Zhang, Reverse-Link Capacity of Power-Controlled CDMA Systems with Beamforming, IEEE Transactions on Vehicular Technology, vol. 53, no. 5, pp – 1433, Sept Related Works Motivation Non of them have consider the co-channel and side- lobes interferences in their system performance simulations.

APAN 2005, , July 2005Ng Chee Kyun16 Co-Channel and Side-Lobes Interferences

APAN 2005, , July 2005Ng Chee Kyun17

APAN 2005, , July 2005Ng Chee Kyun18 Joint Multiple Access System Reverse Link Capacity C I I I I I I I I BS 0 BS 1 BS 2 r0r0 rmrm Intra-cell interference Inter-cell interference

APAN 2005, , July 2005Ng Chee Kyun19 System Parameters for Capacity Analysis

APAN 2005, , July 2005Ng Chee Kyun20 System Capacity in Intra-Sector Interference Environment

APAN 2005, , July 2005Ng Chee Kyun21 System Capacity in Intra-Sector Interference Environment For the 0.01 outage probability, the system capacity increases from 45 users per sector in omnidirectional antenna case to about 200 users per sector if smart antenna is exploited. This depicts an increase of %.

APAN 2005, , July 2005Ng Chee Kyun22 System Capacity in Inter-Sector Interference Environment

APAN 2005, , July 2005Ng Chee Kyun23 When a comparison of system capacity is considered between intra and inter cells interference environment, it depicts a significant decrease. For example, the total users that can be accommodated in a cell are 30 users. It shows that the number is dropped from 200 users per cell yield about 85 % decreases. System Capacity in Inter-Sector Interference Environment

APAN 2005, , July 2005Ng Chee Kyun24 Smart Antenna Beamwidth Sizes

APAN 2005, , July 2005Ng Chee Kyun25 System Capacity in Inter-Sector Interference Environment for Smart Antenna with Its Number of Antenna Elements, n = 8, 16, 32 and 64.

APAN 2005, , July 2005Ng Chee Kyun26 For the 0.01 outage probability, the system capacity increases from 8 users per sector for n = 8 elements case to about 40 users per sector if n = 64 elements are used, which depicts an increase of 400 %. If 0.1 outage probability is considered, the system capacity is further increase from 25 users per sector for n = 8 elements case to about 170 users per sector if n = 64 elements are used, which give a 580 % increase. System Capacity in Inter-Sector Interference Environment when the Beamwidth become Narrower

APAN 2005, , July 2005Ng Chee Kyun27 Concluding Remarks The system capacity will be increased by taking the advantage of both code and spatial signature schemes to distinguish each user. The most realistic reverse link capacity performance of this joint system has been depicted by taking into consideration of prevailing co-channel and sides-lobes interferences in both intra-cell and inter-cell environments. The obtained results have also revealed that the system capacity is further deteriorated by interfering users from neighbouring cells. However, this deterioration can be compensated if the synthesized beams of smart antenna are narrower. Therefore, the system capacity of this joint multiple access system will significant increase spatial diversity becomes more dominant by increasing the number of element in smart antenna system.

APAN 2005, , July 2005Ng Chee Kyun28 Thank You