3g-g
19th March 2007, 06:22 PM
Have you ever wondered what the obligations OFCOM set the UK operators? I quite like the way they could possibly measure if the ops have met the 80% target, OFCOM might choose just to ask if they have. Well, that'll save a lot of bother won't it?! :rolleyes:
Ofcom expects all 3G licensees to meet the requirements for rollout as stated in their licences by the end of 2007.
2.1 An auction of Wireless Telegraphy Act Licences for 3G mobile telephony services was held in the UK in early 2000. Following that auction, five licences were granted to the winning bidders.
2.2 These licences authorise the establishment, installation and use of apparatus to use the specified frequency assignments until 31 December 2021. These licences contain a condition which requires the licensees to meet certain targets for rollout of their networks. Specifically, paragraph 4(a) of the Schedule to each licence provided:
The Licensees shall install, maintain and use Radio Equipment (as specified in paragraph 10 of Schedule 1) in such a way as to enable the provision of, by not later than 31 December 2007, and to maintain thereafter, a telecommunications service by means of the Radio Equipment to an area where at least 80% of the population of the UK live. This condition is referred to in this document as the rollout obligation.
2.3 http://www.ofcom.org.uk/static/archive/spectrumauctions/main.htm
2.4 Since the award of these licences, all licensees have invested in the development of 3G networks, and have launched services that are now commercially available.
2.5 Ofcom set out its proposed approach to ensuring compliance with the obligation in the Spectrum Framework review: Implementation Plan in January 2005. Ofcom published its conclusions about the enforcement of the obligation on 28 July 2006, taking account of the responses received: that document also set out proposals for the technical assessment methodology by which compliance would be measured.
2.6 This document provides a summary of the technical issues raised in response to the consultation of 28 July 2006. Ofcom has taken into account the responses received and has updated its proposals in the light of them.
2.7 How Ofcom intends to measure compliance can be found in section 3. Section 4 provides details of the steps Ofcom intends to take during 2007 and 2008 to measure compliance. Analysis and conclusions of the responses to the 3G Rollout consultation can be found in Annex 1. A revised list of the technical parameters is included in Annex 2. Default antenna patterns are provided in Annex 3.
3.1 This section discusses in detail the methodology Ofcom will use to determine the degree to which licensees meet the obligation to provide a telecommunications service by means of the Radio Equipment to an area where at least 80% of the population of the UK live.
3.2 The description of the obligation contained within the 3G licences gives Ofcom considerable freedom to choose the methodology and detailed parameters for evaluating compliance. The parameters and the measurement methodology are important for the licensees and will be essential so that all parties can understand what is required to reach compliance with the obligation.
3.3 In its consultation Ofcom proposed four basic methodologies that could be employed:
Engineering analysis by Ofcom;
Physical field strength measurement by Ofcom or an agent;
Combination of the above two approaches; and
Operator self-declaration (either based on prediction, measurement or a
combination).
3.4 Ofcom intends to use a methodology based on engineering analysis, backed up by measurements in the field to verify the results as necessary.
3.5 Ofcom intends to issue a request for tender by an outside organisation to provide an independent verification of Ofcoms own analysis by the use of supplementary field strength measurements. The work to be tendered for will be broken into three parts:
Develop the field trial methodology;
Test run to verify the field trial methodology; and
Carry out the field trials. (The number of which will be defined in the field trial methodology).
3.6 3G networks can offer a broad range of services, from simple voice and text to advanced video calling and multimedia. Ofcoms proposed approach to measuring the coverage of networks reflects this variety.
3.7 The mix of services available at any location will depend on decisions taken by operators for example about cell size and the number of simultaneous users supported. The proposed approach measures where a range of basic and advanced services are available under normal conditions, but recognises that this range may not be available there to all users at all times. Considerations for engineering analysis by Ofcom
3.8 There are certain factors that need to be considered when deciding the analytical approach that Ofcom takes in assessing an operators coverage. One such factor is the metric on which to base any prediction, i.e. some estimate of power received to enable the provision of a telecommunications service. Another such factor is the assumption on cell loading.
3.9 An assessment of coverage based on total power received would not give a true indication of whether a telecommunication service was available, as not all of the total power is used in providing a telecommunications service. This approach would tend to overestimate coverage.
3.10 The effects of cell breathing (the cell range effectively shrinks when a cell is heavily loaded) mean that the service level achieved at the edge of the coverage area changes as traffic changes. It is possible that the available coverage area could be different at different times of day due to changes in traffic levels/cell loading.
3.11 The primary common pilot channel (Primary CPICH) is used for cell selection, reselection and handover. The handset must be able to receive sufficient Primary CPICH power in order to initiate a 3G call. Ofcom considers that reception of the Primary CPICH is a suitable proxy for the provision of a telecommunication service.
3.12 The percentage of total downlink power that operators devote to the Primary CPICH is a configurable variable under the control of the operator. The literature suggests that it is normally chosen to be within the range 515 % of the total downlink power. This choice allows a trade-off to be made in areas where coverage is more important than capacity and vice versa. If coverage is more important (say in rural areas) the proportion of the total power allocated to the Primary CPICH is set as high as possible, which leaves less power available to telecommunications services. If capacity is more important (say in urban/suburban areas) the cells will be smaller therefore not requiring as much power for the Primary CPICH thus leaving more power available to devote to capacity and higher data rate services.
3.13 Analysis conducted by Ofcom indicates that, with Primary CPICH power set within the range 5 15%, telecommunications services up to data rates of 384 kbits/s should be available at the edge of a cell (at least for a lightly loaded cell).
3.14 Ofcom assumes that Primary CPICH power of 10% of the maximum transmit power in our analysis is likely to be indicative of urban/suburban deployment and therefore a value within this range is appropriate for our analysis of coverage of 80% of the population. Higher Primary CPICH powers of 10% and above are more likely to be used in less densely populated areas outside the 80% coverage area.
Signal level
3.15 As indicated above, Ofcom proposes to use reception of the Primary CPICH as a proxy for the provision of a telecommunication service. In order to conduct this analysis the minimum signal strength that constitutes reliable reception of the Primary CPICH needs to be established. Ofcom will use Recommendation ITU-R P.1546-2 as the propagation model in its calculation of the received Primary CPICH signal strength. This International Telecommunications Union (ITU) recommendation provides a methodology for point-to-area predictions for terrestrial services such as 3G services.
3.16 Ofcom intends to use service availability as a guide in the selection of the slow fade margin. This margin is used to define the minimum receive signal level at the cell edge.
3.17 If the fade margin is selected such that the service availability at the cell edge is at least 90%, then it can be shown that the service availability over the entire cell should theoretically be greater than 97%. If there are neighbouring cells and handover is possible then the service availability over the entire coverage area should rise to better than 99%.
3.18 If the service availability at the cell edge is to be 90% then the fade margin must be 1.3 times the standard deviation of slow fading (assuming a normal distribution).
3.19 The mobile receiver sensitivity given in the 3G specifications (3GPP TS 25.101) is - 117dBm.
3.20 ITU-R P.1546-1 quotes a standard deviation for slow fading of 5.5 dB for channels wider than 1 MHz. Therefore the minimum received signal level is calculated using a slow fading margin of 5.5 dB x 1.3.
3.21 The minimum signal level required to be received by the handset in order that it can see the Primary CPICH across the whole coverage area to better than 99% probability is therefore -117 + (5.5 x 1.3) = -110 dBm.
3.22 Ofcom will use a Primary CPICH signal level of -110 dBm for the purpose of assessing the edge of the 3G coverage1.
3.23 If coverage was to be assessed for indoor use then an additional margin would need to be included in the calculation for the minimum receive signal level to take account of propagation losses through walls, etc. However, the rollout obligation does not specify that coverage must be indoors, and therefore Ofcom will not include such a margin.
3.24 In order to assess coverage to the population it is necessary to have a database of the population against location for the UK (i.e. where people live).
3.25 Ofcom will use the 2001 census data. For specific detail of assessing the population coverage percentage, please see Annex 2. 1 -110 dBm is relative to an isotropic antenna..
Ofcom expects all 3G licensees to meet the requirements for rollout as stated in their licences by the end of 2007.
2.1 An auction of Wireless Telegraphy Act Licences for 3G mobile telephony services was held in the UK in early 2000. Following that auction, five licences were granted to the winning bidders.
2.2 These licences authorise the establishment, installation and use of apparatus to use the specified frequency assignments until 31 December 2021. These licences contain a condition which requires the licensees to meet certain targets for rollout of their networks. Specifically, paragraph 4(a) of the Schedule to each licence provided:
The Licensees shall install, maintain and use Radio Equipment (as specified in paragraph 10 of Schedule 1) in such a way as to enable the provision of, by not later than 31 December 2007, and to maintain thereafter, a telecommunications service by means of the Radio Equipment to an area where at least 80% of the population of the UK live. This condition is referred to in this document as the rollout obligation.
2.3 http://www.ofcom.org.uk/static/archive/spectrumauctions/main.htm
2.4 Since the award of these licences, all licensees have invested in the development of 3G networks, and have launched services that are now commercially available.
2.5 Ofcom set out its proposed approach to ensuring compliance with the obligation in the Spectrum Framework review: Implementation Plan in January 2005. Ofcom published its conclusions about the enforcement of the obligation on 28 July 2006, taking account of the responses received: that document also set out proposals for the technical assessment methodology by which compliance would be measured.
2.6 This document provides a summary of the technical issues raised in response to the consultation of 28 July 2006. Ofcom has taken into account the responses received and has updated its proposals in the light of them.
2.7 How Ofcom intends to measure compliance can be found in section 3. Section 4 provides details of the steps Ofcom intends to take during 2007 and 2008 to measure compliance. Analysis and conclusions of the responses to the 3G Rollout consultation can be found in Annex 1. A revised list of the technical parameters is included in Annex 2. Default antenna patterns are provided in Annex 3.
3.1 This section discusses in detail the methodology Ofcom will use to determine the degree to which licensees meet the obligation to provide a telecommunications service by means of the Radio Equipment to an area where at least 80% of the population of the UK live.
3.2 The description of the obligation contained within the 3G licences gives Ofcom considerable freedom to choose the methodology and detailed parameters for evaluating compliance. The parameters and the measurement methodology are important for the licensees and will be essential so that all parties can understand what is required to reach compliance with the obligation.
3.3 In its consultation Ofcom proposed four basic methodologies that could be employed:
Engineering analysis by Ofcom;
Physical field strength measurement by Ofcom or an agent;
Combination of the above two approaches; and
Operator self-declaration (either based on prediction, measurement or a
combination).
3.4 Ofcom intends to use a methodology based on engineering analysis, backed up by measurements in the field to verify the results as necessary.
3.5 Ofcom intends to issue a request for tender by an outside organisation to provide an independent verification of Ofcoms own analysis by the use of supplementary field strength measurements. The work to be tendered for will be broken into three parts:
Develop the field trial methodology;
Test run to verify the field trial methodology; and
Carry out the field trials. (The number of which will be defined in the field trial methodology).
3.6 3G networks can offer a broad range of services, from simple voice and text to advanced video calling and multimedia. Ofcoms proposed approach to measuring the coverage of networks reflects this variety.
3.7 The mix of services available at any location will depend on decisions taken by operators for example about cell size and the number of simultaneous users supported. The proposed approach measures where a range of basic and advanced services are available under normal conditions, but recognises that this range may not be available there to all users at all times. Considerations for engineering analysis by Ofcom
3.8 There are certain factors that need to be considered when deciding the analytical approach that Ofcom takes in assessing an operators coverage. One such factor is the metric on which to base any prediction, i.e. some estimate of power received to enable the provision of a telecommunications service. Another such factor is the assumption on cell loading.
3.9 An assessment of coverage based on total power received would not give a true indication of whether a telecommunication service was available, as not all of the total power is used in providing a telecommunications service. This approach would tend to overestimate coverage.
3.10 The effects of cell breathing (the cell range effectively shrinks when a cell is heavily loaded) mean that the service level achieved at the edge of the coverage area changes as traffic changes. It is possible that the available coverage area could be different at different times of day due to changes in traffic levels/cell loading.
3.11 The primary common pilot channel (Primary CPICH) is used for cell selection, reselection and handover. The handset must be able to receive sufficient Primary CPICH power in order to initiate a 3G call. Ofcom considers that reception of the Primary CPICH is a suitable proxy for the provision of a telecommunication service.
3.12 The percentage of total downlink power that operators devote to the Primary CPICH is a configurable variable under the control of the operator. The literature suggests that it is normally chosen to be within the range 515 % of the total downlink power. This choice allows a trade-off to be made in areas where coverage is more important than capacity and vice versa. If coverage is more important (say in rural areas) the proportion of the total power allocated to the Primary CPICH is set as high as possible, which leaves less power available to telecommunications services. If capacity is more important (say in urban/suburban areas) the cells will be smaller therefore not requiring as much power for the Primary CPICH thus leaving more power available to devote to capacity and higher data rate services.
3.13 Analysis conducted by Ofcom indicates that, with Primary CPICH power set within the range 5 15%, telecommunications services up to data rates of 384 kbits/s should be available at the edge of a cell (at least for a lightly loaded cell).
3.14 Ofcom assumes that Primary CPICH power of 10% of the maximum transmit power in our analysis is likely to be indicative of urban/suburban deployment and therefore a value within this range is appropriate for our analysis of coverage of 80% of the population. Higher Primary CPICH powers of 10% and above are more likely to be used in less densely populated areas outside the 80% coverage area.
Signal level
3.15 As indicated above, Ofcom proposes to use reception of the Primary CPICH as a proxy for the provision of a telecommunication service. In order to conduct this analysis the minimum signal strength that constitutes reliable reception of the Primary CPICH needs to be established. Ofcom will use Recommendation ITU-R P.1546-2 as the propagation model in its calculation of the received Primary CPICH signal strength. This International Telecommunications Union (ITU) recommendation provides a methodology for point-to-area predictions for terrestrial services such as 3G services.
3.16 Ofcom intends to use service availability as a guide in the selection of the slow fade margin. This margin is used to define the minimum receive signal level at the cell edge.
3.17 If the fade margin is selected such that the service availability at the cell edge is at least 90%, then it can be shown that the service availability over the entire cell should theoretically be greater than 97%. If there are neighbouring cells and handover is possible then the service availability over the entire coverage area should rise to better than 99%.
3.18 If the service availability at the cell edge is to be 90% then the fade margin must be 1.3 times the standard deviation of slow fading (assuming a normal distribution).
3.19 The mobile receiver sensitivity given in the 3G specifications (3GPP TS 25.101) is - 117dBm.
3.20 ITU-R P.1546-1 quotes a standard deviation for slow fading of 5.5 dB for channels wider than 1 MHz. Therefore the minimum received signal level is calculated using a slow fading margin of 5.5 dB x 1.3.
3.21 The minimum signal level required to be received by the handset in order that it can see the Primary CPICH across the whole coverage area to better than 99% probability is therefore -117 + (5.5 x 1.3) = -110 dBm.
3.22 Ofcom will use a Primary CPICH signal level of -110 dBm for the purpose of assessing the edge of the 3G coverage1.
3.23 If coverage was to be assessed for indoor use then an additional margin would need to be included in the calculation for the minimum receive signal level to take account of propagation losses through walls, etc. However, the rollout obligation does not specify that coverage must be indoors, and therefore Ofcom will not include such a margin.
3.24 In order to assess coverage to the population it is necessary to have a database of the population against location for the UK (i.e. where people live).
3.25 Ofcom will use the 2001 census data. For specific detail of assessing the population coverage percentage, please see Annex 2. 1 -110 dBm is relative to an isotropic antenna..