Is95 System Engineering

IS95 system engineering Song Pengpeng

Fundamentals of CDMA--- Orthogonal spreading sequences ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Fundamentals of CDMA---Vocoder ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Fundamentals of CDMA --- Power Control ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],BTS compares the FER on the forward link reported by MS via PMRM message and adjusts its forward link power. BTS monitors Eb/No on the reverse link and informs MS to adjust its transmission power BTS adjusts Eb/No threshold according to FER measurement Mobile adjusts its power via:

Fundamentals of CDMA --- Power Control @ BTS ,[object Object]

Fundamentals of CDMA --- Power Control @ MS ,[object Object]

Fundamentals of CDMA --- Soft Handoff ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Part I: IS95 system characteristics--- Layered structure ,[object Object]

Part I: IS95 system characteristics---Forward traffic link ,[object Object],Why use quadrature PN sequence? Why use long PN code here?

Part I: IS95 system characteristics---Reverse traffic link ,[object Object],Usage of orthogonal modulation due to the non-coherent nature of reverse link OQPSK--- this chip delay is to make sure that the QPSK signal envelope will not collapse to zero

Part I: IS95 system characteristics---Pilot Channel ,[object Object],[object Object],[object Object]

Part I: IS95 system characteristics---Sync Channel ,[object Object]

Part I: IS95 system characteristics---Paging Channel ,[object Object],Why use a long scrambling code here?

Part I: IS95 system characteristics---Paging Channel frame structure ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Part I: IS95 system characteristics---Forward Traffic Channel for Rate Set 1 ,[object Object],the vocoder outputs variable data rate. To reduce overall interference power at a given time when lower rate are transmitted.

Part I: IS95 system characteristics---Forward link modulator ,[object Object]

Part I: IS95 system characteristics---Access Channel ,[object Object]

Part I: IS95 system characteristics---Access Channel frame structure ,[object Object],[object Object],[object Object]

Part I: IS95 system characteristics---Reverse Traffic Channel for Rate Set 1 ,[object Object],to take advantage of voice activity factor to reduce reverse-link power during quieter periods of speech--- to randomly mask out redundant symbols produced by symbol repetition

Part I: IS95 system characteristics---signaling transmission ,[object Object],[object Object],[object Object],[object Object],[object Object],Example: tranffic channel frame structure

Part II: IS95 system design engineering ,[object Object],[object Object],[object Object],[object Object],System design engineering --- Whether or not the CDMA design of the cell, cluster or system will support the basic radio links? --- basic measurements: Ec/Io on pilot,Eb/No on forward traffic channel, Eb/No on reverse traffic channel.

Part II: IS95 system design engineering---Pilot Channel ,[object Object],[object Object],fraction of home base station overhead ERP allocated to pilot power power received at the probe mobile from overhead power emitted by home base station the total traffic channel power received at the probe mobile from the home base station thermal noise power path loss from home base station in the direction to the probe mobile a distance away home base station(sector 0) overhead ERP including pilot, paging, and sync powers in the direction to the probe mobile the total traffic channel power received at the probe mobile from all other base station sum of overhead powers from other base stations receiver antenna gain of probe mobile power received at the probe mobile from other interference of non-CDMA origins

Part II: IS95 system design engineering---Forward link analysis ,[object Object],[object Object],Processing gain ,[object Object],the forward traffic channel ERP intended for mobile but radiated in the direction toward the probe mobile

Part II: IS95 system design engineering---Reverse link analysis ,[object Object],[object Object],[object Object],reverse traffic channel ERP of the probe mobile; the transmit pattern is assumed to be omnidirectional the total interference introduced by the reverse traffic channel transmissios of all the mobiles in the home station (other than the probe mobile) total interference introduced by the reverse traffic channel transmissions of all other mobiles that are not served by the home base station

Part II: IS95 system design engineering---PN offset planning ,[object Object],IS95 specifies usable PN sequences need to have a minimum separation of 64 chips between each other. Thus, the maximum number of usable PN sequence is 512. ,[object Object]

Part II: IS95 system design engineering---PN offset planning ,[object Object],[object Object],R is the radius of cell 2

Part II: IS95 system design engineering---PN offset planning ,[object Object],In order to avoid PN 1 arrives seemingly before PN 2, the necessary condition is:

Part III: IS95 performance engineering ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Part III: IS95 performance engineering ,[object Object],Conclusion: SRCH_WIN_A at least twice the maximum of the path differences

Part III: IS95 performance engineering ,[object Object],[object Object],[object Object],[object Object],[object Object],trouble symptoms Possible reason solution High forward FER High forward FER and dropped calls; but low mobile received power Insufficient forward-link coverage due to large forward path loss or low traffic channel ERP Increase forward traffic channel ERP or add an additional BTS High forward FER High forward FER and high mobile received power Large forward link interference Reduce number of forward traffic channels; reducing pilot pollution; adjusting the antenna oritentation of neighboring BTS High reverse FER High reverse-link FER and high mobile transmit power Poor reverse-link coverage due to power control---the MT tries to increase its transmitting power moreover Add an additional BTS High reverse FER High reverse FER and high BTS received power Large reverse-link interference Reducing home cell antenna height or orientation

Part IV: Traffic engineering ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Part IV: Traffic engineering ,[object Object],[object Object],[object Object],[object Object]

Part IV: Traffic engineering ,[object Object],[object Object],[object Object],[object Object],=number of users in the same cell =energy-per-bit of the signal =baseband data rate =thermal noise power = loading factor as the ratio of interference introduced by mobiles served by other cells to interference introduced by mobiles served by the home cell Soft-blocking occurrs when the total interference level exceeds the background noise level by a predetermined amount where

Part IV: Traffic engineering ,[object Object],Dividing the above formula by yields Appoximates:

Is95 System Engineering

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