This document provides an overview of key cellular coverage concepts including cell splitting, channel grouping, carrier to interference ratios, tower distance to cell radius ratios, and cellular network architecture. It explains how these concepts are used to efficiently provide cellular coverage and maximize channel capacity.

1. Cellular Coverage Concepts (FRP-CCC)

2. FRP-CCC © Copyright 2001 Global Wireless Education Consortium All rights reserved. This module, comprising presentation slides with notes, exercises, projects and Instructor Guide, may not be duplicated in any way without the express written permission of the Global Wireless Education Consortium. The information contained herein is for the personal use of the reader and may not be incorporated in any commercial training materials or for-profit education programs, books, databases, or any kind of software without the written permission of the Global Wireless Education Consortium. Making copies of this module, or any portion, for any purpose other than your own, is a violation of United States copyright laws. Trademarked names appear throughout this module. All trademarked names have been used with the permission of their owners .

3. FRP-CCC Partial support for this curriculum material was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement Program under grant DUE-9972380 and Advanced Technological Education Program under grant DUE‑9950039. GWEC EDUCATION PARTNERS: This material is subject to the legal License Agreement signed by your institution. Please refer to this License Agreement for restrictions of use.

4. Table of Contents Overview 5 Learning Objectives 6 History of Wireless Communication 7 Cell Splitting 12 Channel Grouping 16 Carrier to Interference (C/I) Ratio 26 Tower Distance to Cell Radius (D/R) Ratio 30 Cellular Network Architecture 41 Summary 45 Contributors 48

5. Overview In this module, you will learn about about cellular coverage concepts that affect the ability to provide the best cellular coverage in the most efficient manner.

6. Learning Objectives After completing this module, you will be able to: Explain how cell splitting and channel grouping are achieved in a cellular network Explain how to calculate a C/I ratio Calculate a D/R ratio Determine the C/I interference for a given D/R ratio Draw a diagram of a cellular network architecture

7. History of Wireless Communication

8. History of Wireless Communications About 100 years of Radio... 1914 Radio first used for practical communication in WWI 1920s First radio broadcasting and simplex mobile broadcast 1940s Radar first used in WWII 1950s First commercial television 1950s First mobile telephony

9. Specialized Mobile Radio (SMR) SMR was used primarily for commercial use Two way over air communication between two or more mobile units Coverage limited to area the signal could reach If signal got too weak, call was dropped No handoffs Calls to the PSTN through a provided dial pad Public Service Telephone Network (PSTN) SMR Provider

10. Cellular Telephone Arrives Make coverage areas smaller, but more of them Develop a means to hand call from one coverage area to another Call these coverage areas cells Delicious Catering Base Station Digital Mobile Switching Center Delicious Delicious Delicious Public Switched Telephone Network (PSTN)

11. Cells Become Crowded Number of users outgrew number of channels available More efficient reuse plan had to be developed Digital Mobile Switching Center Public Switched Telephone Network (PSTN)

12. Cell Splitting

13. Cell Splitting Basic N=7 frequency reuse plan 3 6 6 2 2 5 7 4 1

14. Cell Splitting Basic N=7 frequency reuse plan 3 6 6 2 5 7 4 1 3 6 2 2 5 7 4 1 3 6 2 5 7 4 1 2 5 7 4 1 3 2 5 7 7 3 6 2 5 7 4 1

15. Cell Splitting 3 6 6 2 2 5 7 Basic N=7 frequency reuse plan with split cells 1 1 4 1 1 6 3 4 5 3

16. Channel Grouping

17. AMPS Cellular Bands Cellular telephony provides full-duplex communications Two-way simultaneous conversation requires simultaneous voice paths in both directions 25 MHz band of frequencies used for mobile transmission (uplink) 25 MHz band of frequencies used for cell site transmission (downlink) Cellular bands divided equally between two competing operators A operator B operator 824 835 845 870 880 894 869 849 846.5 825 890 891.5 Uplink Downlink Paired Bands Frequency ( MHz) Uplink Downlink

18. 800 MHz Channel Assignments by Band

19. 800 MHz Telecommunications Band A, non-extended VCH B, non-extended VCH A, extended VCH B, extended VCH A, Control Channels B, Control Channels 799 717 667 666 716 355 312 354 334 001 1023 991 333 313 Legend: System A System B VOICE CHANNELS CONTROL CHANNELS CHANNELS VOICE CHANNELS non-extended exten- ded non-extended extended A’ B VOICE A”

20. Transmit and Receive Channel Separation

21. Cell Clusters – Frequency Reuse R 1 2 3 4 5 6 7 D N=7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 11 12 10 9 8 1 2 3 4 5 6 7 11 12 10 9 8 D R N=12 3 2 1 2 4 3 4 R D N=4 1

22. A Band N = 7 Channel Sets

23. B Band N = 7 Channel Sets

24. Cell Splitting 3C1 (17) 6F2 (8) 6F1 (11) 2B1 (18) 2B2 (19) 5E1/2 (24) 7G1 (14) 4D1 (12) 1A1 (15) Basic N=7 frequency reuse plan

25. Sector Cell Cluster N=7 B1 B2 B3 C1 C2 C3 G1 G2 G3 A1 A2 A3 D1 D2 D3 E1 E2 E3 F1 F2 F3 F1 F2 F3 REUSE 120 degree sector

26. Carrier to Interference (C/I) Ratio

27. C/I is Carrier-to-Interference Ratio AMPS modulation characteristics require  18 dB co-channel C/I over single interferer (  17dB over multiple interferers  ) Between a pair of sites using same channel, three C/I regions exist: Site A C/I better than 18 dB Neither site gives usable C/I Site B C/I better than 18 dB Other sites needed to serve region where neither A nor B has good C/I Rate of signal decay determines how close next co-channel site can be and how many additional sites on other channels are needed in between With proper planning, it is possible to determine required separation between co-channel sites to avoid interference Co-Channel Interference Model -120 -110 -100 -90 -80 -70 -60 Distance, km 1 3 5 7 9 11 13 15 17 19 21 23 25 0 Site A Site B -50 C/I = 18 dB C/I = 18 dB Good Service Good Service Interference RSSI, dBm Frequency Reuse Scenario

28. Co-Channel Interference Uplink/Reverse Path Co-channel interference can occur on uplink, downlink, or both On the uplink, interference occurs at cell site receiver, from mobiles in surrounding co-channel cells 1 1 1 2 3 4 5 6 7 4 6 4 7 2 7 2 5 3 5 3 6 1 1 1 1

29. Co-Channel Interference Downlink/Forward Path On the downlink, interference occurs at mobile user’s receiver due to signals from surrounding co-channel cells 1 1 1 1 2 3 4 5 6 7 4 6 4 7 2 7 2 5 3 5 3 6 1 1 1 1

30. Tower Distance to Cell Radius (D/R) Ratio

31. Use D/R to determine how few cells ( N ) can be tolerated in frequency assignment repetition pattern Co-channel cells must be separated by at least D/R D/R Determines Required Minimum N Example of N=7 D f1 f7 f2 f1 f3 f6 f4 f2 f5 f4 f7 f1 R R D = Distance between two co-channel transmitters R = Coverage radius where a cell is the best server N = ( ) 2 3 D R /

32. Reuse Plan Design Criteria Two design constraints with cellular reuse plans Need to maintain C/I ratio of 18 dB to avoid co-channel interference, but... Want to divide channel sets into as few groups as possible to maximize number of channels per cell Closely related to development is the D/R ratio Distance between cells using same channel sets versus radius of each cell We can show that

33. Frequency Reuse Implications of N N is number of cells in frequency reuse pattern and is critically important since it determines: Capacity of an individual cell Channels per cell = (total channels) / N As N goes up, capacity progressively decreases Interference As N goes up, interference becomes progressively less troublesome Channels per Cell* D/R 395 198 132 99 79 66 56 49 44 1.732 2.449 3.000 3.464 3.873 4.243 4.583 4.899 5.196 40 5.477 36 5.745 N 1 2 3 4 5 6 7 8 9 10 11 12 33 6.000 * Assumes use of 395 voice channels including expanded spectrum

34. Channel Assignment Channel set - collection of channels which could be assigned at one cell Channels in a channel set Normally are N channels apart, where N is reuse factor Must meet combiner minimum frequency spacing requirements Sets 1 and 3 (i.e.,1 and N) are adjacent frequencies If N=3, for example: 1 2 3 4 5 6 7 8 9 10 12 Channels Freq. Channel Set 1 1, 4, 7, 10, . . . Channel Set 2 2, 5, 8, 11, . . . Channel Set 3 3, 6, 9, 12, . . . 1 2 3 2 3 1 1 1 2 3 3 2 N=3

35. Cell Arrangement as a Function of N N=1 Lethal, works well in CDMA Awful C/I: Every neighbor is co-channel Every neighbor cell is adjacent channel too! Center 1/3 of each cell OK, rest is lost in horrible interference N=2 Better, but still lethal Each cell still has 2 co-channel neighbors Each cell has 4 adjacent channel neighbors 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 2 2 2 2 2 2

36. N = 3 Better, but still lethal Co-channel neighbors are now spaced at D/R of 3.0 - better, but not 18 dB.... Each cell has 6 adjacent channel neighbors - all neighbors are adjacent!! N = 4 Better, but still lethal Co-channel neighbors are now spaced at D/R of 3.464 Each cell has 4 adjacent channel neighbors Cell Arrangement as a Function of N 2 3 1 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 1 2 3 4 1 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 3 4 4 4 2 4 4 4

37. N = 5 Better, but not good enough Co-channel neighbors farther away 2 at D/R of 3.0 4 at D/R of 4.58 Some cells have 2 adjacent channel neighbors, some have 3 N = 6 Better, but not by much Co-channel neighbors farther away 2 at D/R of 3.464 2 at D/R of 4.58 2 at D/R of 6.0 Some cells have 2 adjacent channel neighbors, some have 3 Cell Arrangement as a Function of N 1 5 2 3 4 1 5 2 1 2 1 2 3 1 5 2 3 4 1 5 4 1 5 1 5 6 2 3 4 1 5 6 2 3 4 1 5 6 4 1 6 2 1 2 3 6 1 2 3 4 5 1

38. N = 7 First arrangement that works in most propagation environments, giving 18+ dB C/I Co-channel neighbors farther away 6 at D/R of 4.58 Each cell always has 2 adjacent channel neighbors N = 8 Better, but not worthwhile Co-channel neighbors farther away 4 at D/R of 4.58 2 at D/R of 6.0 2 at D/R of 6.93 Of the eight cells in the cluster, 2 have 2 adjacent-channel neighbors and 4 have 1 adjacent channel neighbor Cell Arrangement as a Function of N 1 5 3 8 2 6 4 7 1 5 3 7 1 7 1 5 3 8 2 6 4 1 8 2 6 1 8 2 6 4 1 5 4 7 1 4 7 1 5 3 8 1 2 3 4 5 6 7 4 6 1 1 1 1 1 1 4 7 2 7 2 5 3 5 3 6

39. N = 9 Significant improvement Co-channel neighbors farther away 6 at D/R of 5.20 Out of 9 cells in cluster, 4 have 1 adjacent channel neighbor and 3 have 2 such neighbors N = 10 Not impressively better Co-channel neighbors farther away 2 at D/R of 4.58 2 at D/R of 6.0 2 at D/R of 6.06 Out of 10 cells in cluster, 6 have 1 adjacent channel neighbor 3 have 2 adjacent-channel neighbors Cell Arrangement as a Function of N 1 2 3 4 5 6 7 8 9 1 2 3 6 7 1 2 6 7 4 4 5 8 9 1 3 5 8 9 1 1 4 6 8 1 3 5 7 1 2 3 4 5 6 7 8 9 10 1 2 4 6 1 3 5 9 1 2 6 7 9 10 1 3 7 9 10 1 4 8 1 5 8

40. N = 11 Slightly better Co-channel neighbors farther away 2 at D/R of 4.58 2 at D/R of 6.06 4 at D/R of 7.14 Out of 11 cells in cluster, eight each have one adjacent channel neighbor N = 12 Excellent but inefficient Co-channel neighbors farther away 6 at D/R of 6.0 No adjacent-channel neighbors Cell Arrangement as a Function of N 3 7 11 6 10 10 9 12 4 12 8 1 5 1 8 1 9 8 1 9 5 5 2 3 2 3 6 10 7 11 8 5 1 9 4 12 2 3 2 11 1 1 10 7 7 10 7 6 2 3 4 5 6 7 10 11 1 9 8 2 3 6 7 10 1 2 6 10 1 2 5 6 10 1 9 3 4 7 10 11 1 8 3 7 1 4 5 11 1 9 8 5 11 1 9 4 11 1 8

41. Cellular Network Architecture

42. Diagramming a Network Build a basic cluster of cells using the N factor Try to minimize number of adjacent channels Build a cluster that is repeatable G B D E A F C

43. Building a Network Duplicate the cluster as many times as needed to cover designated area Only one thing is left Supervisory audio tone (SAT) code D G B E A F C G B D E A F C G B D E A F C G B D E A F C G B D E A F C G B D E A F C 1 G B E A F C

44. SAT Assignment Plan for N=7 Omni Systems SAT frequencies are transmitted on analog voice channels to: Provide circuit supervision Validate identity of measured signals during locate process preceding handoff SATs are assigned so that : No cell has near co-channel neighbors with same SAT No adjacent cell has same SAT SAT Frequencies SAT 0 5970 Hz SAT 1 6000 Hz SAT 2 6030 Hz 2 0 1 1 0 1 0 2 0 1 0 2 0 2 1 2 0 2 1 2 1 0 1 2 1 0 1 0 2 0 1 0 2 0 2 0 1 2 1 0 1 0 1 2 0 0 2 0 2

45. Summary

46. Summary In this module, you were introduced to: History of wireless communication Cell splitting Channel grouping C/I ratio D/R ratio Network architecture

47. Summary In this module, you were introduced to: The history of wireless communication Cell splitting Channel grouping C/I ratio D/R ratio Network architecture

48. Industry Contributors AT&T Wireless ( http://www.attwireless.com ) Lucent Technologies, Inc. ( http://www.lucent.com ) Motorola ( http://www.motorola.com ) RF Globalnet ( http://www.rfglobalnet.com ) Telcordia Technologies, Inc ( http://www.telcordia.com ) The following companies provided materials and resource support for this module:

49. Individual Contributors The following individuals and their industry or educational institutions provided materials, resources, and development input for this module: Dr. Cheng Sun California Polytechnic State University http://www.calpoly.edu/ Dave Voltmer Rose-Hulman Institute of Technology http:// www.rose-hulman.edu /