1. Point-to-area communication 2. Coordination 3. Interference SMS4DC training seminar 24 – 29 June 2006 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 Type of communications (ITU-R 1 V.662-3) : • point-to-point communication (2.07) • point-to-multipoint communication (2.08) • point-to-area communication (2.09) Point-to-point communication: Communication provided by a link, for example, a radio-relay link between two stations located at specified fixed points ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 2 1 Point-to-multipoint communication: Communication provided by links, for example, radio-relay links between a single station located at a specified fixed point and a number of stations located at specified fixed points. ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 3 Point-to-area communication: Communication provided by links between a station located at a specified fixed point and any number of stations located at non-specified points in a given area which is the coverage area of the station located at the fixed point. Land Mobile Broadcasting ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 4 2 ITU-R recommendations for point-to-area communication : • P.370 ( Broadcasting ) VHF AND UHF PROPAGATION CURVES FOR THE FREQUENCY RANGE FROM 30 MHz TO 1 000 MHz Broadcasting services • P.529 ( Land Mobile ) PREDICTION METHODS FOR THE TERRESTRIAL LAND MOBILE SERVICE IN THE VHF AND UHF BANDS • P.1546 ( Land Mobile & Broadcasting ) METHOD FOR POINT-TO-AREA PREDICTIONS FOR TERRESTRIAL SERVICES IN THE FREQUENCY RANGE 30 MHz TO 3 000 MHz 5 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 FIGURE 1a P.370 Field strength (dB( µ V/m)) for 1 kW e.r.p. 90 80 70 60 h 1 = 1 200 m 50 Field strength (dB(µV/m)) h1 : the effective height of the transmitting antenna is defined as its height over the average level of the ground between distances of 3 and 15 km from the transmitter in the direction of the receiver h1 = h1 = 40 600 m 300 m 30 20 h1 = 150 m h1 = m 75 h1 = 37.5 m 10 0 – 10 – 20 – 30 – 40 – 50 10 20 50 100 200 400 Logarithmic scale 600 800 1 000 Linear scale Distance (km) Frequency: 30-250 MHz (Bands I, II and III); land; 50% of the time; 50% of the locations; h2 = 10 m; ∆ h = 50 m Free space D01 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 6 3 FIGURE 9 Field strength (dB( µ V/m)) for 1 kW e.r.p. P.370 (Cont.) 90 80 70 60 50 h 1 = 1 200 m Field strength (dB(µV/m)) 40 h 1= 600 m h 1= 300 m 30 20 10 h 1 = 150 m h 1 = 75 m h 1 = 37.5 m 0 – 10 – 20 – 30 – 40 – 50 10 20 50 100 200 400 600 Logarithmic scale 800 1 000 Linear scale Distance (km) Frequency: 450-1 000 MHz (Bands IV and V); land; 50% of the time; 50% of the locations; h2 = 10 m; ∆ h = 50 m Free space D16 7 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 P.370 (Cont.) For locations other than 50%, probability distribution curves are presented in Figs. 5 and 12. FIGURE 5 FIGURE 12 Ratio (dB) of the field strength for a given percentage of the receiving locations to the field strength for 50% of the receiving locations Ratio (dB) of the field strength for a given percentage of the receiving locations to the field strength for 50% of the receiving locations 20 40 15 30 10 20 10 Ratio (dB) Ratio (dB) 5 0 –5 – 10 – 20 – 15 – 20 0 – 10 – 30 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 Percentage of receiving locations 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 Percentage of receiving locations Frequency: 30-250 MHz (Bands I, II and III) Frequency: 450-1 000 MHz (Bands IV and V) Analogue systems Digital systems (>1.5 MHz bandwidth) – 40 Analogue systems D12 Digital systems (>1.5 MHz bandwidth) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 D19 8 4 P.370 (Cont.) FIGURE 6 Application of the parameter ∆ h for broadcasting services ∆h : the parameter ∆h is used to define the degree of terrain irregularity; for broadcasting services it is applied in the range 10 km to 50 km from the transmitter. 10% ∆h Tx 90% 0 50 km 10 Distance from transmitter FIGURE 7 FIGURE 8 Attenuation correction factor as a function of the distance d (km) and ∆ h Attenuation correction factor as a function of the distance d (km) and ∆ h 30 30 ∆ h ( m ) = 500 25 20 ∆ h ( m ) = 500 15 300 10 At te nua tion correcti on factor (dB ) A ttenuation correction factor (dB) 25 150 100 80 5 50 0 30 20 –5 – 10 D13 50 15 150 10 100 80 5 50 0 30 10 10 300 20 –5 100 150 200 250 300 20 10 – 10 0 10 Distance, d (km) 50 100 150 200 250 300 Distance, d (km) Frequency: 80-250 MHz (Bands II and III) D14 D15 Frequency: 450-1 000 MHz (Bands IV and V) 9 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 P.370 (Cont.) If more precision is required for predicting the field strength for reception conditions in specific areas, e.g. in a small receiving area, a correction may be made based on a “terrain clearance angle”. FIGURE 19 Terrain clearance angle θ negative θ 10 m Tx FIGURE 17 Terrain clearance angle correction factor 16 km 20 UHF 10 m θ positive 10 θ VHF Rx D29 Terrain clearance angle : This angle, θ, should be representative of those angles in the reception area, which are measured between the horizontal at the receiving antenna and the line which just clears all obstacles within 16 km in the direction of the transmitter. The example in Fig. 19 also indicates the sign convention which is negative if the line to the obstacles is above the horizontal. Correction (dB) 0 – 10 – 20 – 30 – 40 – 20 – 15 – 10 –5 Clearance angle, θ (degrees) 5 0 D27 Where the relevant terrain clearance angle information is available, Fig. 17 (or the equivalent equations) should be used in place of the ∆h correction . ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 10 5 P.1546 FIGURE 17 FIGURE 1 2 000 MHz, land path, 50% time 100 MHz, land path, 50% time 120 120 110 110 100 100 90 90 80 80 Maximum (free space) Maximum (free space) 70 70 60 60 Field strength (dB(µV/m)) for 1 kW e.r.p. Field strength (dB(µV/m)) for 1 kW e.r.p. 50 50 h1 = 1 200 m 40 30 h1 = 10 m 20 10 0 30 20 h1 = 10 m 10 0 –10 –10 –20 –20 Transmitting/base –30 1 200 m 300 m 75 m 600 m 300 m 150 m 75 m –60 37.5 m 20 m –70 1 200 m –50 150 m –60 antenna heights, h1 –40 600 m –50 Transmitting/base –30 antenna heights, h1 –40 –80 h1 = 1 200 m 40 37.5 m 20 m –70 10 m –80 1 10 100 1 000 10 m 1 10 100 1 000 Distance (km) Distance (km) 50% of locations 50% of locations h2: representative clutter height h2: representative clutter height 1546-01 1546-17 11 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 P.1546 (Cont.) FIGURE 26a FIGURE 27 Terrain clearance angle: the general case Terrain clearance angle correction 2 000 MHz 600 MHz θ positive Correction (dB) 100 MHz θ R (m) 16 km 25 20 15 10 5 0 –5 –10 –15 –20 –25 θ negative R (m) θ –30 100 MHz –35 600 MHz 2 000 MHz –40 Rx Tx 0 10 20 30 40 50 Terrain clearance angle (degrees) 1546-26a 1546-27 This angle, θ, is measured relative to the line from the receiving/mobile antenna which just clears all terrain obstructions in the direction of the transmitter/base antenna over a distance of up to 16 km but not going beyond the transmitting/base antenna. ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 12 6 Effective height clculation Spreadsheet of stations and picture of effective height of a station ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 13 P.370 : point-to-area calculation • • • • • • • • Time percentage (1 to 50%) Location percentage (1 to 99%) Earth Curvature (k-factor) System type (Analog and digital) Environment (Urban Area, Rural Area, Suburban Area) Land/See Discrimination key, Clearance Angle key, Receiver height Area calculation using ITU-R P.370 propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 14 7 P.1546 : point-to-area calculation • • • • • • Time percentage (1 to 50%) Location percentage (1 to 99%) Earth Curvature (k-factor) Land/See Discrimination key, Clearance Angle key, Service (Urban Mobile, Suburban or Rolling hills Mobile, Analog Broadcasting, Digital broadcasting) Receiver height Environment (Open Area, Rural Area, Urban Area, Dense Urban Area, Suburban Area) • • Area calculation using ITU-R P.1546 propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 15 P.525 : point-to-area calculation • • k-factor Receiver height Area calculation using ITU-R P.525 propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 16 8 Hata : point-to-area calculation • • • • Hata Equation (User Defined): Lets user to customize equation coefficients Receiver height Earth Curvature (k-factor) Environment (Open Area, Rural Area, Urban Area, Dense Urban Area, Suburban Area) Area calculation using ITU-R P.529 propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 17 Overlay Calculation An example for application of “Overlay Calculation” ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 18 9 Network Processor : Maximum Field Strength Item to calculate and visualize the maximum value of field strength values produced by more than one transmitting stations at any point inside a predefined rectangular area. Application of maximum field strength method in analysis of a three-station network using ITU-R P.370 propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 19 Network Processor : Maximum Field Strength (Cont.) Application of maximum field strength method in analysis of a three-station network using Okumora-Hata propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 20 10 Network Processor : Maximum Field Strength (Cont.) Application of maximum field strength method in analysis of a three-station network using Free-Space propagation model ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 21 Network Processor : Best Server Item to calculate and visualize the best serving station at each point among various stations inside a predefined rectangular area. Three-station network processing using best server method under P.370 propagation model (a) Best server result without considering clearance angle (b) Best server result considering clearance angle ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 22 11 Network Processor : Best Server (Con.) Application of best server method in analysis of a three-station network (a) Using Free-Space propagation model (b) Using Okumora-Hata propagation model 23 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 Contour calculation By selection of this item, users could define a threshold value. Contour calculation Area calculation 1) Tx location 1) Tx location 2) Rx location 3) Model 4) Field Strength 2) Field Strength 4) Rx location 3) Model E = E0 (dBuV/m) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 24 12 Contour calculation (Cont.) Draw Contour from File: Item to load and display saved vectors on active area calculation result window. ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 25 Coverage Area Item to calculate area in km2 where inside the area, the field strength value is higher than a threshold value. E < Threshold Value E > Threshold Value ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 26 13 Coordination ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 27 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 28 GE84 14 GE84 : BC to BC Coordination Distance ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 29 GE84 : BC to BC Coordination Distance (Cont.) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 30 15 GE84 : BC to BT Coordination Distance ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 31 GE84 : BC to BT Coordination Distance (Cont.) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 32 16 GE84 : BC to FX Coordination Pb : Nearest point to border Border Country Y Country X BC Station E(Pb) > 0 FX stations in Country Y are affected REGION Y : 3 (GE84 Final acts Chapter 5) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 33 GE84 : BC to LM Coordination (Cont.) Pb : Nearest point to border Border Country Y Country X Country Y : MCO(Monaco) E(Pb)>14 & H polarization E(Pb)>6 & (V or M) polarization Region Y : 3 E(Pb)>18 & H polarization E(Pb)>0 & (V or M) polarization BC Station LM stations in Country Y are affected (GE84 Final acts Chapter 4) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 34 17 Definitions Minimum usable field strength (GE89 CHAPTER 1) Minimum value of field strength necessary to guarantee satisfactory service quality in the presence of natural and man-made noise but in the absence of interference from other transmitters. Reference usable field strength (GE89 CHAPTER 1) The agreed value of the usable field strength that serves as a reference or basis for the Plan. Protection ratio (RR 1.170) The minimum value of the wanted-to-unwanted signal ratio, usually expressed in decibels, at the receiver input, determined under specified conditions such that a specified reception quality of the wanted signal is achieved at the receiver output. ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 GE84 : Interference from (Usable Fst.) Interference from selected stations to wanted station Es1, Es2,......., Esi Es1 Es2 Eu ( Determination of the usable field strength by the simplified multiplication method ) 35 Esi Wanted Station Selected Stations Protection ratio : (SM.851) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 36 18 GE84 : Interference from (Usable Fst.) (Cont.) If (E50+As) (Et+At) Protection ratio = As else Protection ratio = At ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 37 GE84 : Interference to (Usable Fst.) Interference from wanted station to selected stations Es1 Es2 Esi Eu Wanted Station Selected Stations ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 38 19 ST61 : [BC , BT] to [BC , BT] - Coordination Distance ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 39 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 40 20 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 41 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 42 21 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 43 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 44 GE89 22 GE89 : BT to BT - Coordination Distance ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 45 GE89 : BT to BT - Coordination Distance(Cont.) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 46 23 GE89 : BT to FX Coordination (Fst.) RPR : relative protection ratio FX Esi rc Sea hR s a d iu Ff Wanted BT Station Fw Ff = Fw ± frequency scan range f = Ff - FvW Fs = FsW - FvW Fc = 3.579 NTSC Fc = 4.43 PAL or SECAM Elimit = -2 - RPR + g(dB) g(dB) : h correction factor Esi = Et + erp - 30 + Lp ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 47 GE89 : BT to FX Coordination (Fst.) (Cont.) Lp : Percentage of receiving locations Correction factor Esi > Elimit FX stations are affected ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 48 24 GE89 : BT to LM Coordination (Fst.) Esi = Et + erp - 30 + Lp + Height_gain Height_gain = 20log10(h2/10) Lp : Percentage of receiving locations Correction factor LM rc Sea Esi hR s a d iu Fm Wanted BT Station Fw Elimit_m Fm = Fw ± frequency scan range Esi > Elimit Elimit = Elimit_m + g(dB) g(dB) : h correction factor LM stations are affected 49 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 GE89 : FX,LM to BT Coordination (Fst.) f = Fw - FvT Fs = FsT - FvT Fc = 3.579 NTSC Fc = 4.43 PAL or SECAM BT rc h Sea Em R ad ius 46 49 53 59 Ft Wanted FX,LM Station FSmin Fw Elimit = Fsmin - 58.0 - RPR + g(dB) Ft = Fw ± frequency scan range Em = Et + erp - 30 + Lp RPR : relative protection ratio g(dB) : h correction factor Em > Elimit BT stations are affected ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 50 25 GE89 : Interference from BT - BT (Usable Fst.) Interference from selected stations to wanted station BT Es2 rc Sea Esi Selected BT Stations Fm Es1 hR s a d iu Wanted BT Station Fw Fm = Fw ± frequency scan range Eu Es1, Es2,......., Esi ( Determination of the usable field strength by the simplified multiplication method ) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 51 GE89 : Interference to BT - BT (Fst.) Interference from wanted station to selected stations Es2 Esi Selected BT Stations Fm Es1 rc h Sea R ad ius Wanted BT Station Fw Fm = Fw ± frequency scan range ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 52 26 Interference 53 ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 Interference Interference by by Noise Noise Wanted field strength Ew Minimum field strength Emin Noise level En C/N Noise wanted TX Criteria for coverage Wanted Field Str. > Minimum Field Str. Ew > En + C/N Coverage area ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 Emin 54 27 Interference Interference by by one one Transmitter Transmitter Nuisance field En Wanted field strength Ew Protection ratio Interfering field strength Ei C/N Noise Coverage area with noise only Criteria for coverage Wanted Field Str. > Nuisance Field Str. Ew > Ei + PR En Coverage area with one interfering Tx ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 55 Interference Interference by by several several Transmitters Transmitters Usable field strength Eu Ew Ei 2 Protection ratio Ei 1 C/N Noise Coverage area with noise only Coverage area with several interfering Tx Criteria for coverage Wanted Field Str. > Usable Field Str. m Ew > Ejn j =1 Σ Eu ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 56 28 Interference BC to BC (Coverage) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 57 Interference BC to BC (Usable Fst.) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 58 29 Interference BT to BT (Coverage) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 59 Interference BT to BT (Usable Fst.) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 60 30 Interference : FX2FX (Link) (Interference to) Interference from the wanted Hop to the selected Hop(s) (above 1 GHz) Propagation Model : P.452 Sele ct ed Tx Hop Rx nt Wa Tx p Ho ed Rx Rx frq.S = Tx frq.W ± frequency scan range ect Sel Rx op ed H Tx ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 Interference : FX2FX (Link) (Interference from) Interference from selected Hop(s) to the wanted Hop 61 (above 1 GHz) Propagation Model : P.452 Selec op ted H Rx Tx Tx nt Wa p Ho ed Rx Tx frq.S = Rx frq.W ± frequency scan range Hop Selected Tx Rx ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 62 31 Interference : FX2FX (station) (Interference to) Interference from the wanted Tx station to the selected RX station(s) (above 1 GHz) Propagation Model : P.452 Rx Tx Wanted Tx Rx Rx frq.S = Tx frq.W ± frequency scan range Selected Rx Threshold Degradation : TD = 10 log10 (1 + 10( I − N ) /10 ) dB ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 63 Interference : FX2FX (station) (Interference from) Interference from the Tx selected station(s) to the Rx wanted station (above 1 GHz) Propagation Model : P.452 Tx Rx Wanted Rx Tx Rx frq.S = Tx frq.W ± frequency scan range Selected Tx ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 64 32 Interference : FXM (Interference to) Interference from the wanted Tx station to the selected RX station(s) (below 1 GHz) Propagation Model : Free Space & P.1546 Rx Fixed Land Mobile Fixed Land Mobile Rx frq.S = Tx frq.W ± frequency scan range Wanted Tx Rx Selected Rx ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 65 Interference : FXM (Interference from) Interference from the selected Tx station(s) to the wanted Rx station (below 1 GHz) Propagation Model : Free Space & P.1546 Tx Fixed Land Mobile Fixed Land Mobile Tx frq.S = Rx frq.W ± frequency scan range Wanted Rx Tx Selected Tx ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 66 33 Border Coordination Border Xkm Line Cross Border Range (CBR) ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 67 Border Coordination (Cont.) P.1546 Cross Border Range (CBR) (Type A) Land Mobile Cross Border Range (CBR) (Type A) Free Space Model 1 Cross Border Range (CBR) (Type A) P.1546 Frequency < 1GHz Fixed Free Space Frequency 1GHz P.1546 P.452 Cross Border Range (CBR) (Type A) Coordination Distance (Type B) Xkm Line Calculation Land Mobile Free Space Xkm Line Calculation Model 2 P.1546 Fixed Xkm Line Calculation Frequency < 1GHz Free Space Xkm Line Calculation ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 68 34 User Defined Agreements ITU-BDT SMS4DC Regional Seminar for Arab States, Khartoum, Sudan, June 2006 69 35