Introduction to SEAMCAT

1. Introduction to SEAMCAT European Communications Office Jean-Philippe Kermoal - SEAMCAT Manager (ECO) October 2010

2. Outline • Part 1 - Why SEAMCAT? • Part 2 - SEAMCAT-3 software tool • Part 3 - Principles of modelling various systems: • Traditional – SEAMCAT 3.2.X • CDMA – SEAMCAT 3.2.X • Part 4 - SEAMCAT information • Conclusions

3. Part 1: Why SEAMCAT?

4. Spectrum engineering challenges increasing penetration of the existing radio applications regulatory technological introduction of new radio applications economic considerations The requirement for global compatibility amongst many radio systems within a congested radio spectrum

5. Need for spectrum sharing • There are no more “empty” spectrum • Proposed new systems have to find way of “sharing” with some of existing systems • Thus the need for spectrum engineering and optimisation: • to find which existing radio systems are easiest to share with, and then • determine the “sharing rules”

6. Sharing methods • Spacing radio systems in frequency • Using the gaps between existing channels • Spacing geographically • Using the gaps between intended deployment areas (e.g. cities vs. rural areas) • Time sharing • Exploiting different work time (day vs. night) • Working at different power levels • E.g. “underlay” spectrum use by UWB

7. Sharing implementation • Agile (cognitive) radio systems require minimum sharing rules as they could be adapting dynamically • Simple example: finding free channel in a given geographic area • Traditional rigid-design radio system will require precisely defined sharing rules • Maximum transmit power, guard-bands to existing systems, etc

8. Defining the sharing rules • Analytical analysis, usually by worst-case approach: • Minimum Coupling Loss (MCL) method, to establish rigid rules for minimum “separation” • Statistical analysis of random trials: • The Monte-Carlo method, to establish probability of interference for a given realistic deployment scenario • That is where SEAMCAT comes into picture!

9. Wanted Signal Interferer Dmin, or minimum frequency separation for D=0 The MCL approach • The stationary worst-case is assumed Victim • However such worst-case assumption will not be permanent during normal operation and therefore sharing rules might be unnecessarily stringent – spectrum use not optimal!

10. Wanted Signal Active t=t0 t=t1 t=ti Interferer Inactive Interferer Monte-Carlo approach • Repeated random generation of interferers and their parameters (activity, power, etc…) Victim • After many trials, not only unfavourable, but also favourable cases will be accounted, the resulting rules will be more “fair” – spectrum use optimal!

11. Monte-Carlo Assumption • User will need to define the distributions of various input parameters, e.g.: • How the power of interferer varies (PControl?) • How the interferer’s frequency channel varies • How the distance between interferer and victim varies, and many others • Number of trials has to be sufficiently high (many 1000s) for statistical reliability: • Not a problem with modern computers

12. Part 2: SEAMCAT-3 Software tool

14. History • Developed in CEPT as a co-operation between National Regulatory Administrations, ERO, industry • First released in Jan-2000, then gradually developed in several phases • Freely downloadable from ERO website (www.ero.dk/seamcat)

15. Purpose • SEAMCAT is designed for: • Generic co-existence studies between different radiocommunications systems operating in same or adjacent frequency bands • Evaluation of transmitter and receiver masks • Evaluation of various limits: • unwanted emissions (spurious and out-of-band), • blocking/selectivity, etc. • Not designed for system planning purposes

16. SEAMCAT tool • Used for analysis of a variety of radio compatibility scenarios: • quantification of probability of interference between various radio systems • consideration of spatial and temporal distributions of the received signals • Can model any type of radio systems in terrestrial interference scenarios • Based on Monte-Carlo generation

17. Typical examples of modelled system • Mobile: • Land Mobile Systems • Short Range Devices • Earth based components of satellite systems • Broadcasting: • terrestrial systems • DTH receivers of satellite systems • Fixed: • Point-to-Point and Point-to-Multipoint

18. Installing SEAMCAT On-line Webstart: Internet connection is needed at least for the installation; during later runs Internet used (if available) to check for updated version (Windows, Linux etc...) Off-line (Windows only) • No special processor/memory needs • Java RTE should be installed on your PC, at least version 1.6 required

19. Plug-ins User Interface Technical Library Workspace (.sws) Results XML File Event Generation Engine EGE Display CDMA Engine CDMA Display Display Future Calculation Engine Reports XML stylesheets Interference Calculation Engine ICE Display Software architecture

20. Main interface • Windows-oriented • Data exchange via XML files • Main element – workspace: • Simulations input data – scenario: • equipment parameters, placement, propagations settings, etc. etc. • Simulation controls: number of events etc • Simulation results: signal vectors, Pinterference • Physically - an XML file with “sws” extension

21. SEAMCAT-3 software • Conceived in early 2003 • Conceptually the same interface structure as in SEAMCAT-2: workspace based, dialogue views • Main reason: need to model CDMA • Also: improvement of user interfacing and general use convenience • Implemented in Java • Source code available upon request

22. Graphic interface • Shows positions of generated transceivers in victim and interfering systems; • Overview of results (dRSS, iRSS) • Intuitive check of simulation scenario; • Detailed insight into simulated data for modelled CDMA system (last snapshot only);

23. Extra features • Propagation model plug-in API(Application Programing Interface) • Post processing plug-in API • Batch simulation format (Automation of repetitive compatibility studies to be run at once) • Remote computing (Public use of a powerful server at ERO and possibility to set-up local SEAMCAT server) • Custom simulation report (XSLT->XML style sheet)

24. Plug-in • A plug-in is a (little) software programme, which may be developed by the user • Written using standard Java language, compiled using open development tools • The pre-compiled code may be then “plugged-in” at certain “insertion points” of SEAMCAT simulation flow to produce the desired “user-defined” functionality • No perceivable impact on simulation speed

25. Propagation model plug-in • This plug-in may be used to define ANY kind of propagation model, no complexity limit • The plug-in may be inserted at any point where propagation model is defined in the scenario: • Victim link • Interfering link • Interference path • CDMA/OFDMA modules

26. Post-processing plug-in • This plug-in is invoked at the end of the snapshot generation and may be used e.g.: • Powerful API • Introduce user-defined consistency checks • Model some special system design features, e.g. Smart Antennas, etc. • Account for any additional environment features, e.g. terrain/clutter impact, etc • To save intermediate results into external files for signal processing in other tools (Matlab, etc) • not applicable to CDMA (victim)

27. Remote computing • To ease carrying out lengthy simulations

28. Batch simulation • “Batch” function allows automation of repetitive compatibility studies by scheduling several SEAMCAT simulations to be done in one run of the programme • Typical case – to study the impact of change of any one (or few) scenario parameters on the probability of interference • Since version 3, any parameter (and any number of them) could be varied in batch

29. Part 3:Principles of modelling various systems ”Traditional” system CDMA system

30. Start While i=1,N A Generate position data of Wt, Vr Calculate dRSSi B dRSS vector While i=1,N C While j=1,M Generate position data of Itj, Wrj Calculate iRSSi,j D Calculate iRSSiSUM iRSS vector dRSS, iRSS to ICE Main elements of SEAMCAT scenario iRSS dRSS Interfering Transmitter (It) Victim Receiver (Vr) Interfering link Victim link Wanted Transmitter (Wt) Wanted Receiver (Wr)

31. Creating simulations scenario • User defines a scenario, describing mutual positioning of two systems in geographical domain… …as well as many other parameters

32. Scenario parameters • Positioning of two systems in frequency • Powers • Masks • Activity • Etc.

33. Event generation • Random generation of transceivers • Link budget • Signal values

34. How event generation works* • Succession of snapshots… dRSS WT 1) Calculate d, Ptx, GaTx, GaRx, L IT Snapshot# iRSS 2) Calculate dRSSi WT VR VR 2) Calculate iRSSi Snapshot# 1) Calculate d, Ptx, GaTx, GaRx, L 1) Calculate d, Ptx, GaTx, GaRx, L IT 2) Calculate received signal, if PC, adjust Ptx WR WR (*) Except CDMA/OFDMA systems

35. Results of event generation • Vectors for useful and interfering signals: dRSS iRSS

36. Evaluating probability of interference dRSS -> (C) - For each random event where dRSS>sensitivity: Desired signal value (dBm) C/Itrial > C/Itarget? Interfering signal (dBm) Interference (dB) iRSS -> (I) Noise Floor (dBm) - If C/Itriali>C/Itarget: “good” event - If C/Itriali<C/Itarget: “interfered” - Finally, after cycle of Nall events: Overall Pinterference= 1- (Ngood/Nall)dRSS>sens

37. CDMA modelling • Modelling of CDMA systems as victim, interferer, or both: • Voice traffic only; • Quasi-static time within a snapshot; • One direction at a time (uplink or downlink); • Particular CDMA standard defined by setting Link Level Data (CDMA2000-1X, W-CDMA/UMTS) • Impact of interference measured by excess outage (capacity loss due to interference)

38. 3 Results 1 Pre-simulation This part of the GUI is used to assist the user when configuring the workspace. All CDMA specific GUI elements are available as part of either VictimLink or InterferingLink configuration dialogs. 2 Simulation The simulation GUI elements are shown during the simulation and are used to provide information about what SEAMCAT is doing. Since CDMA simulation can take much longer than non-CDMA simulations, there are special GUI parts used to provide information to the user. 4 Detailed information on the last snapshot After a simulation these GUI parts are used to provide access to calculated results but also detailed insight into the last snapshot of the simulation. Inspecting the last snapshot is considered a good way to validate the configuration of the simulated workspace. CDMA procedure

39. Start C While i=1, N While j=1, M Generate position data of Itj, Wrj While j=1, L Iterative process of power balancing in CDMA cells While j=1, M Generate position data of Wtj, Vrj Calculate iRSSi,j D Iterative process of power balancing in CDMA cells Record dRSSi or other parameter, e.g. non-interfered CDMA capacity While k=1, M Generate position data of Itk, Wrk Calculate iRSSi,k Repeat iterative process of power balancing in victim CDMA cells, now with iRSS present as external impact Record impacti of interference, e.g. loss of CDMA capacity (N) records of interference impact To further engines • First a succession of snapshots are run without interference, gradually loading the system to find the target non-interfered capacity per cell • Then the standard range of EGE snapshots is applied to generate the derived number of “target” users • apply interference and note the impact in terms of how many of initial users were disconnected CDMA as victim CDMA as interferer

40. CDMA: Power Control • Modelled CDMA cell is surrounded by two tiers of auxiliary cells, and total cluster of 19 (57 for three-sector deployment option) is considered in power control tuning • Application of Wrap-Around technique for calculation of distance to closest BS produces effect of “endless” uniform network

41. Modelled CDMA cell Interferer-Victim distance Other radio system, counter-part in interference simulation Modelled CDMA cell Two auto-generated tiers of auxiliary CDMA cells

42. Clear legend BS antenna display BS or MS info display General system info Cell specific info Connected - voice active user Active link Inactive link Dropped user CDMA interferer Last snapshot displayed

43. CDMA network-edge case • Instead of centre cell, takes the cell at the edge of CDMA PC cluster as a reference cell, wrap-around formulas adjusted as if no other cells are located beyond that cell • This should be useful for e.g. cross-border or similar interference scenarios

44. Setting Network edge case

45. CDMA results • Initial capacity: Number of connected UEs before any external interference is considered. • Interfered capacity: Results after external interference is applied. • Excess outage, users: How many UEs were dropped due to external interference. • Outage percentage: Percentage of UEs dropped due to external interference. Non-interfered capacity (red) Interfered capacity (blue) Difference (green) Number of connected UE

46. CDMA results

47. Part 4:SEAMCAT information

48. On-line manual www.ero.dk/seamcat www.seamcat.org/xwiki

49. CEPT SEAMCAT workspace publicly available • Existing .sws files which have been generated as part of some ECC report or CEPT reports activities can be found at www.erodocdb.dk

50. Reference material and workspaces