1、STD-CEPT ERC REPORT 101-ENGL 1999 = 2326414 0017210 004 = c ERC REPORT 101 European Radiocommunications Committee (ERC) within the European Conference of Postal and Telecommunications Administrations (CEPT) A COMPARISON OF THE MINIMUM COUPLING LOSS METHOD, ENHANCED MINIMUM COUPLING LOSS METHOD, AND
2、THE MONTE-CARLO SIMULATION Menton, May 1999 L STD*CEPT ERC REPORT 101-ENGL 1999 = 232b414 0017211 T40 ERC REPORT 101 EXECUTIVE SUMMARY WG- SE has been requested by the ERC to recommend a unified method for evaluating the minimum frequency separation between two systems operating in adjacent frequenc
3、y bands. Three methods were identified for comparison. These were the Minimum Coupling Loss (MCL) method, the Enhanced Minimum Coupling Loss (E-MCL) method and the Monte Carlo method. The most important characteristics of the MCL method are: 0 0 0 0 0 the result generated is isolation in dB, which m
4、ay be converted into a physical separation if an appropriate path loss formula is chosen it is simple to use and does not require a computer for implementation it is a worst case analysis and produces a spectrally inefficient result the victim receiver is assumed to be operating 3 dB above reference
5、 sensitivity a single interferer transmitting at fixed (usually the maximum) power and using a single channel is considered. The most important characteristics of the E-MCL method are: O O O the result generated is isolation in dF5, which may be converted into a physical separation and subsequently
6、into a probability of interference it does not require a computer for implementation the victim receiver has a fixed wanted signal strength margin dependent upon system availability interferers are assumed to be uniformly distributed across a circular cell system a fixed victim to interferer frequen
7、cy offset is assumed The path loss figures used by the E-MCL method include fading on the victims wanted signal link (assuming the curves derived by W.C.Jakes are used) but do not include slow fading in the interferer to victim link. The results of initial E-MCL calculations indicate results that ar
8、e of the same order of magnitude as those generated by the Monte Carlo method. Power control may or may not be taken into account. The most important characteristics of the Monte Carlo method are: 0 0 0 0 0 the result generated is a probability of interference it is a statistical technique, which re
9、quires the use of a computer it allows the user to model realistic scenarios and evaluate appropriate minimum frequency separations an appropriate path loss model is required the victim receiver has variable wanted signal strength multiple interferers using multiple channels may be considered the ef
10、fect of features such as power control may be included. The main points to be considered are: 0 the MCL approach is relatively straight forward, modelling only a single interferer-victim pair. It provides a result which, although spectrally inefficient, guards against the worst case scenario. the Mo
11、nte Carlo approach is a statistical technique, which models a victim receiver amongst a population of interferers. It is capable of modelling highly complex systems including CDMA. The result is spectrally efficient but requires careful interpretation. the E-MCL approach provides a useful bridge bet
12、ween the MCL and Monte Carlo methodologies. For relatively simplistic scenarios the results of the E-MCL methodology are of the same order of magnitude as the Monte Carlo. However the methodology is not likely to compare so favourably for ali interference scenarios e.g. CDMA scenarios. As in the cas
13、e of Monte Carlo, the result requires careful interpretation. 0 STDmCEPT ERC REPORT 101-ENGL 1999 232b4L4 OOL72L2 987 ERC REPORT 101 Each of the methodologies has its merits and drawbacks. The appropriate choice depends upon the criteria used and on the tool available to the user. The increasing pen
14、etration of wireless communications is leading to increased congestion in the radio spectrum. This indicates that one criterion should be the ability to evaluate spectrum efficiency. Radio systems are becoming more and more complex as the range of services offered is increased. This indicates that a
15、nother criteria should be the ability to model complex scenarios realistically and with flexibility. Finally, the advent of high-density systems has led to the concept of soft capacity .e. capacity is a function of inter and intra system interference, this concept is fundamental to the case of CDMA
16、systems. Thus the last criteria is the ability to evaluate capacity in a system. In summary the criteria are: Flexibility. the ability of evaluating spectrum efficiency. ability to model complex scenarios realistically. ability to evaluate system performance for high density or CDMA systems. Conside
17、ring these criteria and the following study, the recommended method for evaluating minimum frequency separations is the Monte Carlo simulation. Users of the Monte Carlo simulation should be aware of the following factors: the accuracy of the result obtained will rely upon accurate values being assig
18、ned to each simulation parameter and upon how these parameters are introduced in the simulation. Furthermore, the simulation by an MC tool of particular features available in some systems may require dedicated software modules or code. simulation parameters may be assigned using values from the rele
19、vant radio system standard or using typical equipment values. Care has to be taken in the interpretation of the results, particularly when values of both types have been used. an appropriate path loss model must be used. system hot spots may exist where there are unusually high densities of active u
20、sers potentially generating increased levels of interference. radio functions such as power conml should be included if used in practice. In addition special channel types such as control channels should also be modelled. the probability of interference, which is acceptable, will vary from system to
21、 system and user to user and needs to be carefully interpreted. It has to be noted that what the Monte Carlo simulation is computing will depend upon the scenario being modelled. For simulations where the victims are all treated equally and do not have restrictions placed upon their positions then e
22、ach will experience the same level of interference. In this case the meaning of the result is that 100 96 of the users experience a P 96 probability of being disturbed. For simulations where the position of some or all of the victims is restricted then it is possible that some victims will experienc
23、e more interference than others. In this case the meaning of the result will be somewhere between 100 % of the users experiencing a P % probability of being disturbed and P 96 of users experiencing a 100 % probability of being disturbed. When interpreting a simulation result in terms of what it mean
24、s in the real world, a great deal of care needs to be taken. In reality each mobile user is likely to have an individual pattern of mobile terminal usage. This is likely to be related to where that user lives and works. This means that one user may commonly pass through an area of poor signal qualit
25、y whereas another user may very rarely experience poor signal quality. In this case the P % probability of interference should be interpreted as somewhere between 100 % of the users experiencing a P % probability of being disturbed and P ?I of users experiencing a 100 96 probability of being disturb
26、ed. In addition, it should be kept in mind that Monte Carlo simulations should be used to model hotspos or areas of high mobile terminal usage. It is important to recognise that the result produced is specific to that hotspot and does not apply to all areas or to all users. J L ERC REPORT 101 WG SE
27、has released a specification for a Monte Carlo based radio system compatibility tool. This tool has been named the Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT). It is referred to in document WG SE(97)30 Monte Carlo Radio Compatibility Tool I. SEAMCAT is more sophisticated than t
28、he Monte Carlo radio compatibility tool used in this study. It is recommended that once SEAMCAT is available, CEPT administrations use it to evaluate minimum frequency separations between adjacent systems. It is important to realise that care will have to be taken in using the SEAMCAT tool and in en
29、suring that it is applicable to the scenario being modelled. The first version of the tool may not be applicable to all system scenarios e.g. CDMA systems. Each scenario should therefore be considered on a case by case basis to ensure that the relevant system aspects are being modelled accurately. D
30、iscussions were held in the project team on which could or should be the allowable percentage of interference: no specific figure is recommended, because this has to be chosen depending on the systems and services involved and the specific scenario which has been considered for the compatibility stu
31、dy. It is strongly recommended that such figure is carefully identified on a case by case basis, by the relevant Working Groups and Task Groups of the CEPT, based on both technical elements and economicaYoperationaI constraints (including safety requirements). CEPT ERC Rewrt 68 Monte Carlo Radio Com
32、patibility Tool, 1 http:/www.ero.dk/eroweb/SEAMCAT/SEAMCAT/SEAMCAT.html. The Monte Carlo results in this document have been produced with several different Monte Carlo tools. Those results are proposed only with the purpose of proposing examples for the reader. ERC REPORT 101 INDEX TABLE 1 INTRODUCT
33、ION . . 1 2 STUDY . . 1 2.1 MINIMUM COUPLING LOSS THEORY . 2 Interpretation of the Results . 3 Minimum Coupling Loss Example 3 Unwanted Emissions MCL Analysis - Base Station to Base Station 3 Receiver Blocking MCL Analysis - Base Station to Base Station 6 ENHANCED MINIMUM COUPLING Loss THEORY . 7 Li
34、nk Availability Estimation “Jakes Method” 8 Power Control in the E-MCL Method (interfering system) 10 Victim System without Power Control in the E-MCL Approach 11 Limit Mask Consideration in the E-MCL method . 12 The Basic E-MCL Scenario 12 The Spurious Limit . 12 Example of the Spurious Limit . 13
35、Conclusion of the Spurious Limit . 14 Interpretation of the Results . 14 Enhanced Minimum Coupling Loss Example . 15 Wideband noise E-MCL analysis - Mobile Station to Mobile Station . 15 Blocking E-MCL analysis - Mobile Station to Mobile Station . 19 Monte Carlo as Applied to Radio Systems 22 Interp
36、retation of the Results . 23 Monte Carlo Simulation Example 24 Wideband Noise Monte Carlo Analysis - Mobile Station to Mobile Station 24 Receiver Blocking Monte Carlo Analysis - Mobile Station to Mobile Station . 26 2.4 COMPARISONS . 27 Comparing the Results of the MCL, E-MCL and MC Methods 28 MCLRe
37、sults - Mobile Staion to Mobile Station 28 E-MCL Results - Mobile Station to Mobile Station (unwanted emissions) 30 MC Results -Mobile Station to Mobile Station (unwanted emissions) 30 A Method of Comparing the Monte Carlo and E-MCL Results 30 interferer parameters 31 Conclusions on MCL, E-MCL and M
38、onte Carlo Comparisons 31 3 CONCLUSIONS . 32 2.1.1 2.1.2 2.1.2.1 2.1.2.2 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.4.1 2.2.4.2 2.2.4.3 2.2.4.4 2.2.5 2.2.6 2.2.6.1 2.2.6.2 2.3 MONTE CARLO THEORY 22 2.3.1 2.3.2 2.3.3 2.3.3.1 2.3.3.2 2.4.1 2.4.1.1 2.4.1.2 2.4.1.3 2.4.1.4 2.4.2 APPENDIX A : Relevant Documents for
39、 Information 1995 34 APPENDIX B : BIBLIOGRAPHY 37 APPENDIX C : PATH LOSS MODELS . 37 APPENDIX D : ABBREVIATIONS . 37 ANNEX 1 : INVERSION OF SEAMCAT PROPAGATION MODEL . 38 ANNEX 2 : IMPACT OF THE INTERSECTION OF INTERFERING ZONES IN THE EMCL ANALYSIS 40 ANNEX 3 : EXPLANATION OF THE * 10 Log(l0 “O - 1
40、) B TERM . 42 ERC REPORT 101 Page 1 1 INTRODUCTION This report has been proposed as a result of a request by the ERC to WG-SE to develop a unified method for the determination of minimum frequency separation. The purpose being to allow CEPT member states the ability to adopt a harmonised band plan f
41、ramework with provision for national requirements. This follows on from work carried out on adjacent band compatibility using Minimum Coupling Loss (a link budget methodology), where excessively large minimum frequency separations were produced. In the past, WG SE adjacent band compatibility studies
42、 utilised the Minimum Coupling Loss (MCL) method, based upon minimum receiver sensitivity, to determine both minimum frequency separation and, by the application of an appropriate propagation model, interference distances. However, concerns were raised regarding the pessimistic results given by this
43、 method, particularly since real systems operating on an uncoordinated basis, operate apparently quite satisfactorily with much reduced minimum separation distances. More recent proposals include the statistical Monte Carlo methd and the Enhanced Minimum Coupling Loss (E-MCL) method. The E-MCL metho
44、d is aimed at bridging the gap between the MCL and Monte Carlo methods. The way forward therefore was to implement a comparison study to compare the MCL, E-MCL and Monte Carlo nethods. 2 STUDY The study took the form of an assessment of the essential differences between the three fundamental approac
45、hes, namely the minimum coupling loss (MCL) method, the Enhanced Minimum Coupling Loss (E-MCL) method and the Monte Carlo (MC) simulation. For ease of comparisons this study considers mobile to mobile scenarios. For Minimum Coupling Loss the base to base case is also included. Recommendations are ma
46、de for the method to be used in each Case. For each interference scenario, the following need to be considered: unwanted emissions, i.e. any off-channel noise of the interfering equipment falling within the receive band of the victim receiver, thus acting as cochannel interference to the wanted sign
47、al. In general, this sort of interference can only be removed at the source. blocking, i.e. a strong signal off the receive band of a victim receiver, desensitising its reception. In general, this sort of interference can only be removed at the victim. However, in most cases the adoption of power co
48、ntrol for the interferer and good site engineering can improve the situation. adjacent channel rejection transmitter intermodulation receiver intermodulation In order to compare like with like, the same propagation model should be adopted for all three methods. For the purpose of this comparison, on
49、e of the models developed within WG SE has been used. A number of other models, which could be used, are listed in Appendix C. Technological advantages such as dynamic channel selection, intra-cell handover, error correction, frequency hopping, etc., which can, in some cases, ease the coexistence between different systems, have not been taken into account in this analysis of the different methods. Some of the reasons for this choice are the need for an approach which ensures the long term usability of spectrum, and the inclusion of such features in the different systems make it cont
