1 / 25

Agenda

Call-fail-safe and Distribution-effective Methods for Multi-band Multi-carrier Traffic Allocation in 3GB Wireless Networks. Parthasarathy Guturu EE Department, University of North Texas, Denton. Agenda.

maryfleming
Download Presentation

Agenda

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Call-fail-safe and Distribution-effective Methods for Multi-band Multi-carrier Traffic Allocation in 3GB Wireless Networks • Parthasarathy Guturu EE Department, University of North Texas, Denton

  2. Agenda • Overview of 3G CDMA/WCDMA wireless communications • Single Band Multi-carrier Traffic Allocation Problem • Multi-band Multi-carrier Traffic Allocation- How to contain increased call failure probability? • A class of Multiband Algorithms • Simulation Results • Summary and Conclusion

  3. Power Frequency Time Multiple Access Technologies • How multiple users can share the same medium (air interface) simultaneously? • FDMA (Frequency Division Multiple Access). Each user has a private frequency • TDMA (Time Division Multiple Access). Each user has a private time on a private frequency • CDMA (Code Division Multiple Access). Users co-mingle in time and frequency, but each user has a private code. FDMA Power TDMA Frequency Time Power CDMA Frequency Time

  4. CDMA- Spreading Principle Receiver 1 Transmitter 1 Medium (Air) User 1 Data User 1 Data 1.288 MHZ Spreading Code 1 1.288 MHZ Spreading Code 1 Transmitter 2 Receiver 2 User 2 Data User 2 Data 1.288 MHZ Spreading Code 2 1.288 MHZ Spreading Code 2

  5. H1 H1 H2 = H1 H1 0 0 0 0 0 1 0 1 0 0 1 1 0 1 1 0 0 0 0 1 0 Orthogonal Codes • Two Codes are orthogonal if Exclusive OR operation on them yields equal number of 0’s and 1’s. • Orthogonal (Walsh) Code generation recursively: • Almost orthogonal • Short PN (Pseudo-Noise) • Long PN • Walsh codes used in forward (down, base-station to mobile) link. PN sequences used in reverse (up) link for transmission and scrambling at down link.

  6. Frequency Reuse: Cell Planning in AMPS/TDMA/GSM 1 4 1 7 2 6 3 7 5 1 6 4 1 6 2 1 4 3 7 2 6 3 1 5 1 Since separation of users in CDMA is via orthogonal codes, frequency can be reused virtually every cell.

  7. Generations of Wireless Technologies • First Generation (1G) • AMPS (Analog Mobile Phone Service) using FDMA • NAMPS (Narrow-band AMPS) using FDMA • DAMPS (Digital AMPS) using TDMA • 2G. Ex: GSM (European 2G TDMA) • 3G • Some distinctive features compared to 2G (Next slide) • CDMA & WCDMA (Wideband CDMA) used

  8. VLR AC HLR OK CLR 1 2 3 4 5 6 7 8 9 * 0 # CDMA Network Architecture MSC MSC PSTN VMS BSC MC BSC IWF RNC MSC- Mobile Switching Center BSC- Base Station Controller BTS- Base-station Transceiver System VLR- Visiting Location Register HLR- Home Location Register MC- Messaging Center VMS- Voice Mail System AC- Authentication Center BSC BSC Wireless PPDN MS BTS BTS PSTN- Public Switching Telephone Network PPDN- Public Packet Data Network IWF- Inter Working Function

  9. Distinctive Features of 3G • Addressing of 2G limitations: • Bandwidth limitations (14.4 – 64 Kbps) • Designed originally for voice; low capacity • Low data rates (up to 14.4 Kbps) • Limited Roaming Capabilities • Limited support for packet data • single-service networks • No Multimedia • Asymmetric Data Rates • Bandwidth on Demand • Always Connected (concept of Dormant states)

  10. 3G Wireless Systems & Standards 3G Wireless Standards & Systems CDMA- Code Division Multiple Access UMTS- Universal Mobile Telecommunications System RTT- Radio Transmission Technology UMTS CDMA 2000 (Successor of IS-95) FDD W-CDMA TDD W-CDMA 1xRTT 3xRTT FDD- Frequency Division Duplex TDD- Time Division Duplex EV- Evolution DO- Data Only DV- Data and Voice. 1x EVDO 1x EVDV

  11. Spectrum Allocation • 800 MHZ (cellular) Band • 824-894 MHz, divided into sub-bands, carriers from paired sub-bands used for up/down link communications. • Each RF Carrier is 1.25 MHZ wide • Cellular spectrum of 1 operator is 12.5 MHZ wide, but only 9 carriers can be accommodated because of the need to support AMPS • 1900 (PCS) MHZ • 1850-1990 MHZ, divided into A, B, C sub-bands with 30 MHz each (for 11 carriers) and D, E, F sub-bands 10 MHz each (supporting 3 carriers) • 260 KHz Guard band

  12. MCTA Algorithm • Available carrier capacity may be assessed using either • Forward link power still available for call setup without service degradation • Unused Walsh codes • Limiting the calls on a carrier based on either of the above criteria guarantees QOS. • MCTA is a class of load distribution algorithms based on carrier capacities.

  13. OK CLR 1 2 3 4 5 6 7 8 9 * 0 # Multi-Band Situation- Cell Coverage Problem F I D B C G A E H

  14. Naive Extension of MCTA to Multi-Band Situation Table-1: A typical Cell Site Data Table.

  15. Problem with Naive Extension of MCTA to Multi-Band Situation • Latest version of 3GGPP standard provides for up to 13 bands. Currently 800 and 1900 MHz bands are operational. In Russia, they are trying to introduce 450 MHz band. Using all bands- not cost-effective. • 1-1 overlay systems (cell sites) in different bands may not always be co-located. • Even if they are, position of a mobile accessing a BTS of one band may not covered by the co-located system of the other band. (Radio coverage of the carriers of 800 band is roughly 3 times that of the 1900 band carriers). • If call is redirected to the other band because of its best capacity carrier, call may fail if the best capacity carrier accessible to mobile has no capacity.

  16. Our Min-Max Solution to the Dual Band Traffic Allocation Problem The rationale behind the algorithm: • If a mobile can access a cell site, it can be allocated the best capacity carrier of the cell site. • It is not sure which of the other band cell sites (covering the range of the original cell site of access band) is accessible to the mobile because of its position. • Hence find the best carrier of each one of the other band cell sites and choose the worst among them (min-max carrier) to compare with the inband best carrier of non-zero capacity. • Call is redirected to the other band if the min-max carrier is better. Redirection is done even if inband best carrier has no capacity and at least one carrier in the other band has capacity.

  17. Implementation of the Algorithm • Cell site information (addresses of co-located BTSes and the Cell site IDs of the other band cell sites covering this one) is provisioned and stored in an in-memory database at the BSC. • When MSC sends Call setup request with the original cell site information, BSC requests Capacity information from all the BTSes. • Considering all the responses arrived within a pre-configured time, BSC finds the best carrier of each cell site and applies the min-max algorithm

  18. anMS::MS aBTS::BTS anMSC::MSC aBSC::BSC cellSiteInfoTable:: Table << Mobile-Originated Call >> Originate-Call() Originate-Call() Setup-Call (…) << Mobile-Terminated Call >> Page-Mobile() Page() Process-Page-Response() Process-Page-Response() Setup-Call (…) Get-Access-Carrier-Info (…) Get-Carrier-And-BTS-Info-Lists (…) Execute-MBTA-Algorithm (…) Implementation of the Algorithm

  19. Extensions to the MCTA Algorithm • Development of an Enhanced Capacity Measure (ECM) by augmenting mobile-user specific preferences. • Extension of the dual-band algorithm to the case of more than two bands. ND-Bit SC-Bit RC-Bit RB-bit BPR-Bits CPR-Bits Capacity Magnitude Bits CAC-Bit IBC-Bit ND- Non-downgraded SC-: Spare Capacity RC: Retain Carrier BPR- Band Priority CPR- Carrier Priority CAC- Call Access Carrier IBC- Inband Carrier

  20. Multi-band algorithms • Optimistic algorithm • Best-fit algorihm

  21. Multi-band algorithms (continued) • Best-band algorithm • Firs-fit algorithm • Simply assign call the first band non-zero MinMaxECM.

  22. Call Distribution Effectiveness Measure • Between-and Dispersion • Within-Band Dispersion • Overall dispersion measure

  23. Simulation Experiment • Algorithms for comparison • Optimistic, First-fit, Best-fit and Best-band • Best Distribution (Post-call assignment dispersion) • Criteria for comparative analysis • Distribution efficiency & Robustness against call failures • Setup • 100000 8-site (Fig. 1) configurations with best capacity of each site a random number between 0 and Max-Resources-Available-At-Any-Site. • Experiment is repeated for values of the Max-Resources-Available-At-Any-Site from 1 thru 35

  24. Experimental Results

  25. Conclusions and References Conclusions • Rule out: • Best-band- Computationally Intensive • Optimistic- Failure-prone in overloaded network • First-fit- Good for early call setup, but inefficient from call distribution perspective • Best-fit and Best-band are competitive. Best-fit may be preferable because of simplicity. References • www.uspto.gov search Published patents on string “guturu.’ • Parthasarathy, Guturu and Abdennaceur, Lachtar, “An Efficacious Method for Dual Band Multi-carrier Traffic Allocation in CDMA Wireless Systems,” Proc. IEEE GLOBECOM 2003, Vol. 1, pp.10-14. Also available in IEEE Trans. On Wireless Comm., March 2006. • Sarvesh Sharma and Ahmad Jalali, US Pat.#6,069,871

More Related