WiMAX – EKSPANSI COVERAGE World Interoperability for Microwave Access There are two main applications of WiMAX: 1)Fixed WiMAX (IEEE ) - Fixed WiMAX applications are point-to-multipoint enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL for homes and businesses. 2)Mobile WiMAX (IEEE e-2005) - Mobile WiMAX offers the full mobility of cellular networks at true broadband speeds.
FIXED - WiMAX Fixed WiMAX Architecture
FIXED - WiMAX Mobile WiMAX Architecture
LTE – EKSPANSI DATA RATE LTE is the latest standard in the mobile network technology tree that previously realized the GSM/EDGE and UMTS/HSxPA network Characteristics : Significantly increase peak data rates, scaled linearly according to spectrum allocation improving spectral efficiency lowering costs improving services making use of new spectrum opportunities Improved quality of service better integration with other open standards
LTE Network Architecture
Wireless Mobile Broadband
Mobile Broadband Infrastructure
INTELLIGENT TRANSPORT SYSTEM (ITS)
High Altitude Stratospheric Platform Services (HAPS) Menambah Coverage dan Capacity
PROBLEMS OF WIRELESS CHANNEL Incoming signal consists of several paths with different time delays (multiple copies of the same signal) Intersymbol Interference leads to very slow data rate Signal Fluctuation leads to loss of SNR
FREQ. SPECTRUM LIMITATION
20 FDM vs. OFDM Conventional v/s Modern FDM technique
21 LTE-Downlink (OFDM) Improved spectral efficiency Reduce ISI effect by multipath Against frequency selective fading
22 LTE Uplink (SC-FDMA) SC-FDMA is a new single carrier multiple access technique which has similar structure and performance to OFDMA A salient advantage of SC- FDMA over OFDM is low to Peak to Average Power Ratio (PAPR) : Increasing battery life
23 Multi-antenna techniques
Beam- steering using phase shifters at each radiating element Radiating elements Power distribution Phase shifters Equi-phase wave front = [(2 / )d sin ] 33 22 0 d Beam direction Phased Array Antenna...
MSC BS WLL LOS MSC BS multiple antennas at MS NLOS MIMO techniques different propagation environment Urban area Rural area
SDMA concept - expected up to 8 times capacity improvement - power classes concept (can be dynamic or static) - with ref. signal BF MSs can be separated even when they have the same angular position to BS ! - for DoABF MSs angular distribution is important (macrocell) - network planning (frequency) is simpler, but larger cell size can require new planning, more smooth migration into existing network - more network management upgrade required PCH 1
RESEARCH WIRELESS ACCESS NETWORKS
28 Power Frequency Time Code FDMA TDMA CDMA
DS-CDMA Concepts– Freq domain Signal-to- interference ratio (SIR) Desired SIR will limit the capacity Wrong code will not detect signal Non CDMA signal received at the Rx will be reduced by spreading and filtering jammer suppression Other non- CDMA user User’s code
r(t - 1 ) c(t - ) Despreader Demodulator/Detector D1D1 D2D2 D3D3 r(t - 2 r(t - 3 ) Multipath fading is unavoidable in wireless communications CDMA is wideband Frequency Selective channel Intersymbol Interference (ISI) can be better resolved GSM use equalizer at bit level processing CDMA Rake chip level processing The number of resolvable paths is much higher. Better performance !!
Problem of Power Control - CDMA The main problems of cellular is multipath propagation : – Frequency selective channel due to delay spread propagation. – Signal fluctuation due to mobility CDMA is a spread spectrum multiple access technique that uses large bandwidth (1.25 MHz for narrowband and 5 MHz for wideband CDMA). Coherence Bandwidth for typical multipath channel is in the order of hundreeds KHz CDMA channelis always frequency selective. Need to solve for both problems. (b) Multipath fading problem 2 P t1 P r1 P r2 P t2 d1d1 d2d2 Signal fluctuation User (a) Near-far distance problem Delay spread
Multi Carrier Technique (to solve for frequency selective channel) Carrier bandwidth B u is divided into J subcarriers of bandwidth B d so that B d = B u /J or B u = JB d By Choosing a large number of J, bandwidth of each sub carrier can be made lower than the channel coherence bandwidth to produce a frequency non selective channel.
Multiuser Detection Receiver Conventional receiver detects the signal using each user’s code individually. Multiuser detection /receiver (MUD) use all user’s signal to detect each user signal iteratively. In MUD, MAI is reduced for each iteration r(t - ) c(t - ) Despreader Demodulator c(t - ) Demodulator Interference component will decrease by iteration Other user interference is subtracted using feedback
Performance Of multi user Detection MULTI USER DETECTION IMPROVES DETECTION PERFORMANCE SIGNIFICANTLY Multi User Detection Single User Detection
Penutup/Diskusi Teknik Multi-Carrier merupakan trend teknologi wireless access network yang bisa mengatasi Problem Kanal Wirelss dan Keterbatasan Frequensi Teknik Multi User Detection bisa menghilangkan/mengurangi interferensi, sehingga meningkatkan kapasitas. Kapasitas dan laju data Wireless Communication meningkat tajam dalam 10 tahun terakhir.