Eco-Efficiency Indicator: an Operator’s energy performance Indicator Flavio Cucchietti Telecom Italia Via Reiss Romoli 274, Turin, Italy
[email protected]
Gianluca Griffa Telecom Italia Via Reiss Romoli 274, Turin, Italy
[email protected]
Abstract - In the last ten years, the telecom Operators have made strong actions towards an ever more efficient use of the energy and to its reduction. As the network architecture was stable (service from the Central Office), the effect of these actions was easily measurable. The Next Generation Network (NGN) the Operators are aiming to, implies a completely different and highly distributed scenario, where most of the network equipment will be deployed in FTTCab - FTTB architecture. There is the need to define a method to analyze the energy performance behavior which should be both general and future proof. This method should be applicable both to the current network and to the NGN, assuring a constant and reliable assessment. The proposed method takes into account the ratio between the service delivered (in terms of bits) and the total energy used by the Operator (Joules). Telecom Italia is developing a comprehensive Indicator representing its Fixed and Mobile networks performance. The energy sources taken into account are: industrial (energy used by the network plants), civil (offices, lighting) and fuels (car and heating fuel). The document will depict the results of the application of such an Indicator to the Telecom Italia case. It will analyze its trend on 2003 - 2006 period, detailing all the key factors and their mutual action on the final result.
I. ENERGY AND TRAFFIC: THE CURRENT TRENDS In the last years, the energy factor has assumed an increasingly importance for different players: public and private companies, States, as well as individual citizens. This is due to two main aspects: • the cost of energy has noticeably grown and is still far from stopping. Just to give an example, the unit cost of electrical centralized energy in Italy has doubled in only five years (period 2000 – 2005) • at the same time, also the global energy consumption is constantly rising (as shown in figure 1), with all the environmental issues brought by this situation. As a consequence, the explosive compounding between the unit costs and the total energy consumption has triggered several actions aimed both to a progressive reduction (or at least containment) of the energy demand, and to the research of alternative sources. Focusing on the Telco sector, it must be first of all underlined the huge amount of energy (of different sources) needed (especially by an Incumbent) in order to create and maintain a fixed and/or mobile network.
Lorenzo Radice Telecom Italia Via Meravigli 7, Milan, Italy
[email protected]
Figure 1: World Energy Consumption
Taking into account the Telecom Italia current situation, some numbers (strictly related to the Italian market) are given below in order to better explain the complexity of the problem: • around 25 million of fixed lines, and 33 million of mobile ones (29 GSM and 4 UMTS); • around 11.000 Central Office (CO) sites, of which around 8.000 with ADSL; • more than 7.500.000 broadband lines; • almost 150.000 Outdoor Cabinets; • 100 million kilometers of copper network and 4 million kilometers of optical fiber; • more than 2TWh of electrical power consumption in 2006, representing nearly 1% of the total National energy demand (second user only to the National Railways). Up to few years ago, the network was just fixed and was basically in a steady state: the only traffic was represented by the vocal calls, the issue of the power consumption wasn’t felt as strategic, and the actions towards energy savings were limited to port concentrations and replacements of obsolete equipments. The rapid diffusion of the mobile telephony and, above all, the fixed broadband penetration that started at the end of the nineties (see figure 2) caused the addition of new active equipments and, therefore, the progressive rise of the “energy issue”. Moreover, the continuous demand for more bandwidth is bringing towards a saturation of the ADSL capacity (the maximum theoretical speed per user is 8 Mbit/s for ADSL and 24 Mbit/s for ADSL2+).
Traffic Italy (bln minutes)
C DN
700
4 TIM CDN OLO CDN
5
600
BB Traffic (F+M)
500
DSLAM ATM
ATM Network
6
il
CDN Mobile Network
NLC
400
reta
ATM NAS
2 IP/OPB Network
NRP
1
7
DSLAM IP
300
100 1.0 2000
2001
2002
2003
2004
2005
2006
2007
Figure 4: network scheme for TI Eco-Efficiency Indicator % of Gbit traffic towards NAS ATM closing locally without proceeding towards the OPB network 1
2008
ATM traffic (Gbit) towards OPB network (recorded at POP transit level) 2
ATM traffic
Figure 2: voice and data traffic evolution in Italy (source: TI) Central Office
MDU
Home
xDSL
CO
Cabinet
300 - 3500 m
100 - 700 m
xDSL ONU
OLT
FTTB
20 - 200 m
OLT
FTTH
Medium Term
Limit
ADSL2+ ADSL2+ 3-20 Mbps 3-20Mbps 20-500 M 1 Gbps
1-10 Gbps
>10 Gbps
Figure 3: access architecture and performance (source: TI)
Therefore, new technologies and even new architectures are needed in order to fulfill the new requirements (see figure 3). In particular, the evolution towards FTTCab and FTTB architectures implies the introduction of new active equipments scattered in wide areas. In addition, the implementation of an “overlay” solution (BroadBand served from the Cabinet while POTS/ISDN continues to be delivered from the CO) will bring to further and huge power consumptions. On the other hand, however, it must be underlined that the great amount of energy that will be needed to support the new architectures will enable to provide to the customers faster services with a greater QoS. This, in the end, can be seen as an improvement of the social welfare. II. THE ECO-EFFICIENCY INDICATOR The need for an Eco-Efficiency Indicator rises from the need to link the unchallenged advantage for the community brought by the evolution of network and services to the impact on the environment which has been considered proportional to the energy required. Therefore, the Indicator should represent one of the ways to evaluate the Company’s sustainability: the higher its value, the better the benefits. The particular Eco-Efficiency Indicator implemented by Telecom Italia takes into account the ratio between the service delivered (in terms of bits) and the total energy used by the Operator (Joules). Concerning the numerator, voice and traffic data, both from fixed and mobile network have been taken into account to form a comprehensive indicator.
PSTN Network
3
NB Traffic Voice Mobile Voice Fixed
200
ATM traffic (Gbit) towards OLO Network 4
CDN OLO
Mobile telephony (CDN TIM)
ATM traffic on OPB
CDN retail
OPB traffic Fixed telephony on OPB
% of total of OPB traffic originating from fixed telephony – on the basis of peak traffic 7
Traditional Fixed Telephony
Fixed telephony traffic in minutes subsequently converted in Gbit 3
OPB traffic (Gbit) recorded at POP transit level Total number of CDN Retail: subsequent conversion to Gbit passing from potential traffic to “effective” traffic through an utilization factor 6
2
Mobile telephony traffic in minutes (with hp matching CDN TIM traffic) subsequently converted to Gbit 5
Figure 5: traffic sources for TI Eco-Efficiency Indicator
Regarding the denominator, instead, different energy sources have been included: industrial (energy used by the network plants), civil (offices, lighting) and fuels (car and heating fuel). Moving towards a deeper analysis for the traffic side, in the following are reported the details concerning the different components of the numerator (please refer to figures 4 and 5). First of all, the total minutes of fixed telephony are taken into account (see number 3 in figure 4). The following calls are included: • local fixed calls (same metropolitan district); • national fixed calls; • international fixed calls; • fixed to mobile calls; • calls related to the Carrier Selection (CS) and Carrier PreSelection (CPS) services. The total minutes are then transformed in Gbit through the following formula: Traffic [Gbit] = 77 [kbit/s] * 60 [s/minutes]* 106 * Traffic [minutes]
(1)
Then, remaining in the voice area, the total minutes of mobile telephony are considered (see number 5 in figure 4). In particular, the following calls are included: • mobile to mobile voice calls; • mobile to fixed calls; • video calls; • roaming calls. Also in this case, the total minutes are converted in Gbit/s starting from the codifications reported below: • 22.8 kbit/s (13 kbit/s + redundancy for error correction) for GSM Full Rate (FR); • 11.4 kbit/s (6.5 kbit/s + redundancy for error correction) for GSM Half Rate (HR);
• 21.4 kbit/s for UMTS voice calls; • 64 kbit/s for UMTS video calls. Considering that the total minutes of mobile voice calls used for the Indicator calculation are not split among GSM FR, GSM HR and UMTS, an ex-post attribution is therefore needed. To this end, a first operation is performed in order to obtain an average codification for GSM FR and HR, through the following formula: Average GSM code [kbit/s] = 22.8 * (1 - %HR) + 11.4 * (%HR)
(2)
In particular, the variable %HR depends on the characteristic traffic curve: • during the peak period (about 2.5 hours overall per day), it is assumed that only the HR codification is used, with a percentage of total mobile voice traffic processed equal to 19%; • on the other side, during the “off-load” period (about 12 hours overall per day), it is assumed that only the FR codification is used, with the 19% of total traffic processed; • finally, during the remaining hours of a day (about 9.5), a mixed use of HR and FR is assumed, with the 62% of total traffic processed. Just to give an example, the variable %HR in 2006 is 26%, for a resulting average GSM codification equal to 19.79 kbit/s. Once that the average GSM codification is calculated, the conversion from minutes to bit is realized through the following formula: Traffic [Gbit] 2006= ⎞ ⎛ GSM lines UMTS lines ⎜⎜ * 19.79 + * 21.4 ⎟⎟* 60 * 106 Traffic [Min] (GSM + UMTS) lines ⎠ ⎝ (GSM + UMTS) lines
(3)
Moving towards the data traffic, the most important source is represented (see number 2 in figure 4) by the Optical Packet Backbone (OPB), which consists of 32 Points of Presence (PoP, interconnected through links at up to 10 Gbit/s) and will soon become the only backbone for the entire Telecom Italia network. Currently, the OPB supports: • IP/MPLS transport services for both the Executive/Business (connected via ATM, Frame Relay. ADSL and GbE) and the residential customers (connected via ADSL and dial-up); • Voice services over IP of class4 (interconnection of Backbone nodes) and class5 (VoIP calls); • Interconnection towards Internet Data Centers (IDCs); Another important component for the data traffic is represented by the Asynchronous Transfer Mode (ATM) network (see number 1 in figure 4). This network, although still transports a huge amount of Gbits, will slowly be abandoned in behalf of the new OPB mentioned before. Nevertheless, currently there is still a significant amount of the total ATM traffic that is “terminated locally”, without passing through the OPB network. Only that specific portion of traffic is included in the Indicator.
At this point, is worth to underline that, in order to avoid an overestimation of the Indicator, a strong attention has been put towards a “single” evaluation of the bit. Here’s why only the 15% of the ATM traffic is taken into account (the remaining 85% passes through the OPB network, and therefore is not “duplicated”). Another example of the application of this rule is given by the non-native VoIP (see number 7 in figure 4: in fact, the specific portion of the total OPB traffic that is originated from a packetization of the traditional voice calls is not inserted within the numerator (since it is already considered in number 3 in figure 4). The third main component for the complete traffic mapping is given by the Leased Lines (named CDN in Italy, see number 4 and 6 in figure 4). There are two main typologies of Leased Lines: • Leased Lines dedicated to the Other Licensed Operators (OLO); • Residential Leased Lines (dedicated to private customers and other companies). In the first case, the total amount of Gbit transmitted towards the OLOs is directly available in the ATM Network Database. The only additional operation that needs to be performed is the elimination of the traffic portion strictly related to the Leased Lines used for the backhauling of the Radio Base Stations (RBS) owned by Telecom Italia Mobile. This because, as said before, the Gbits originated from the TI mobile customers are already calculated through the conversion of the total minutes of voice and video calls (see number 5 in figure 4). In this way, the rule of avoiding the redundancies in the Indicator calculation is respected. Regarding the second typology of Leased Lines, considering that Telecom Italia simply provides the access to the customers, it’s not possible to know the exact amount of traffic processed. Therefore, an inevitable rough evaluation is needed. More precisely, starting from the total number of the Residential Leased Lines for each class (nominal speed) K, the following formula is used to calculate the annual traffic: LL Traffic K [Gbit] = Nominal speed K [Gbit/s] * 0,05 * 31.536.000 [s/year]* LL K [# of lines] (4) There are currently five nominal speeds K available for the Residential Leased Lines: 1. < 64kbit/s (in this case, an average value of 32kbit/s is considered for the calculation); 2. N * 64kbit/s (in this case, the average value assigned to N is 2: this category includes the connections towards the Automated Teller Machines); 3. 2 Mbit/s (these connections, together with the N * 64 kbit/s, are the most numerous); 4. 34 Mbit/s; 5. 155 Mbit/s. The value 0,05 (5%) that is used within the formula (4) can be seen as an “Utilization factor”. It is used to estimate the real traffic processed starting from the nominal capacity; it is indicated in many reports about this topic, and also several
analysis carried out by Telecom Italia confirm the reliability of this percentage. Finally, concerning the mobile traffic (see number 5 in figure 4), also the total Gbits associated to the SMS, MMS, GPRS and WAP traffic have been taken into account. As far as the energy components are concerned, the following sources have been considered: • Industrial: this category includes all the electrical power consumption related to the network equipments for both the fixed and the mobile network: DSLAMs, Routers, Switches, PoP, Radio Base Stations, Central Offices, etc; • Civil: this category includes the total electrical power consumption related to the Telecom Italia offices that don’t include network equipments, included those buildings that host data processing centres (e.g. IDC, billing systems, etc); • Fuels: this last category includes the consumption of any other energy type (e.g. the fuel needed for the cars, the heating fuel, etc). It has been included in the denominator because, according to our view, all the activities associated to these consumptions are essential in order to guarantee the service (that is the numerator). II. THE VALUES OF THE ECO-EFFICIENCY INDICATOR The final values for the Telecom Italia Eco-Efficiency Indicator during the period 2003 – 2006 have been inserted in Table I. Before starting a brief data analysis, it must be underlined that the most important goal of the Indicator is not to provide extremely precise information of the network traffic and the company’s power consumptions.
ATM and Leased Lines is the variable that had the most consistent relative growth (in particular, the first component has almost multiplied by ten times from 2003 to 2006): this is mainly due to the remarkable penetration of the ADSL services and to the introduction of flat fees (see figure 7). These two aspects have an impact on both the Telecom Italia’s customers (so therefore mainly on OBP and ATM) and the OLO’s customers (mainly CDN). Also the traffic coming from the mobile network and the electrical energy consumption of the Radio Base Stations (even if associated to less evident gaps) show a continuous growth during the four years considered: in the first case, this is mainly due to a progressive price reduction (that stimulates a greater number of mobile calls) and to an increasing interest towards the VAS (Value Added Services) services (e.g. ringing tone and games downloads). In the second case, the reason can be found in the progressive deployment of the 3G network. Finally, the traffic coming from the fixed voice calls, the electrical energy consumption for the fixed network and the consumption of other fuels highlight a different trend. In particular, the first two components show a continuous reduction: regarding the traffic, this is mainly due to the migration of the Telecom Italia customers towards other fixed or mobile Operators. Main Drivers for Eco-Efficiency indicator 2003 OPB traffic
2004 2005
1,0 0,9
2006
0,8
Other fuels
0,7
ATM traffic
0,6 0,5
TABLE I
0,4 0,3
TI ECO-EFFICIENCY INDICATOR 2003 - 2006
Year
Kbit/kWh Bit/Joule
2003
492.028
2004
777.248
0,2 0,1
RBS consumption
CDN traffic
216
2005 1.311.676
364
2006 2.175.006
604
Fixed network consumption
In fact, rather than having data with the accuracy of a single bit or Watt (the need for a quite fast calculation of the Indicator’s value implies a certain approximation), it’s important to keep a consistent evaluation perimeter, in order to allow a fair comparison of the Indicator through the years. Coming back to the analysis, the trend of the Indicator during the referred period shows a global growth of 341%. In order to better understand the reasons that justify this performance, a year-by-year normalization of the main drivers has been made, through the following formula: Normal value year x,source y =
0,0
137
Nominal valueyear x,source y
Fixed telephony
Mobile telephony
Figure 6: main drivers for TI Eco-Efficiency Indicator
(5)
max(Nominal value year x,source y ) x
The normal values for the different components have been reported in figure 6. As visible, the traffic related to OPB,
Figure 7: flat rat penetration on total access lines
The total electrical energy consumption for the fixed network, instead, has been reduced thanks to a set of specific actions, among which the most important are: • rise of the maximum temperature acceptable within an equipment room; • replacement of energy stations with lower conversion yield; • installation of new Free Cooling plants; • replacement and rationalisation of conditioning plants; • compacting PSTN switching modules; • switch-off of obsolete plants and equipment. It’s worth to be noticed that the above action points have set off against the consumption growth due to the progressive introduction of the DSLAMs in the Central Office. Concerning the consumption of other fuels, it must be underlined that in the last years several actions aimed to a global emission reduction have been taken (e.g. the replacement of the obsolete cars, the substitution of the older hot-water heaters, etc). Another interesting analysis concerns a different year-byyear normalization of the main traffic drivers (see figure 8). More in detail, the following formula has been implemented: Normal value year x,source y =
Nominal valueyear x,source y
(6)
max(Nominal value year x,source y ) y
As visible, while in the previous analysis the comparison was focused on the different values during the reference period for each specific component, now the sight is orthogonal, and the comparison shifts towards different values of different components for each specific year. Therefore, we can state that, while in 2003 the most important driver was represented by the fixed telephony traffic (almost 50% of the total Gbit processed by the Telecom Italia network), during 2006 the most significant source had become the OPB traffic (almost 65% of the total), with the “old winner” overtaken by the CDN traffic and with the ATM traffic at heel. Normal values for the different traffic components
0,70 0,60 0,50
2003 2004
0,40
2005 2006
0,30 0,20 0,10 0,00 OPB traffic
ATM traffic
CDN traffic
Fixed telephony
Mobile telephony
Figure 8: normal values for different traffic components
A final consideration must be done. The structure of the Eco-Efficiency Indicator obviously highlights that, for example, an annual improvement can be obtained if: • given the same amount of total traffic processed, the total power consumption has been reduced;
• given the same total power consumption, the network has been able to process a greater quantity of Gbit. Having said this, while the first statement is commonly considered in a complete positive way, the second one sometimes baffles. To this end, it’s worth to take into account an easy example. Let’s assume to install a new DSLAM (connecting all the ports to the customers), and to have no traffic during the first year. In the second one, let’s assume instead that, due to more convenient prices, all the customers decide to activate the ADSL subscription. The Eco-Efficiency Indicator, therefore, would highlight a good improvement even if no actions have been taken in order to reduce the power consumption: anyway, we can doubtless assert that the system is used in a more efficient way. Consequently, this example also suggests that the Eco-Efficiency Indicator can’t be used “stand alone”, but needs to be joined with other parameters (e.g. the total power consumption) in order to have a complete overview of the Company’s optimization strategy. Since 2006 the values of the Eco-Efficiency Indicator are officially reported (together with other relevant parameters) within the annual Telecom Italia Sustainability Report [6]. In addiction to the final value for 2006, a target for 2007 has been reported. More in detail, starting from 604 bit/Joule (see table I), a precautionary percentage growth of 40% has been assumed, obtaining an estimated value of 850 bit/Joule for end of 2007. The reason why (although the last three percentage growths were respectively 58%, 69% and 66%) a lower rate has been used depends basically on two considerations: • the ADSL lines are gradually reaching a saturation; • there could be some bandwidth limitations, depending on saturation peaks within the core network. Contextually, during 2007, the need for a quarterly update of the Eco-Efficiency Indicator has emerged: the last available calculation related to the first quarter highlights a value of 873 bit/Joule: this means that things are currently going well, even if the incoming summer should trigger an increase of the energy consumption due to the equipments’ cooling. III. NEXT STEPS In order to introduce the possible next steps, it must be premised that Telecom is not the only company that has started using an Eco-Efficiency Indicator structured as previously described. In particular, the example of Swisscom can be reported [3], [4]. It must be underlined that the charts reported in figure 9 don’t have the purpose of directly compare the punctual values of the two Eco-Efficiency Indicators, since a process with the goal of perfectly homogenize the formulas at the base of the calculation has not (yet) been performed. Instead, two considerations can be highlighted: 1. the idea of represent the Eco-Efficiency Indicator with the ratio between bit and Joule is valuable; 2. the trend associated to the Telecom Italia Indicator and the Swisscom’s one is comparable.
600
507 500
400
305
Also in this case, the main hurdles towards the above proposal are represented by: • the current absence of a fine assignment of the power consumption actually absorbed among the different network equipments; • the difficulty to accurately split the network traffic among the different Telecom Italia services.
300
189 200
123 100
0
Figure 9: comparison between Swisscom (left) and Telecom Italia (right) Eco-Efficiency Indicators
Just to give another example, also Telia Sonera is working on the definition of an Energy Index, in order to quantify and analyze the energy efficiency [5]. Starting from the above observations, a first possible next step could be the promotion, among the different worldwide Telco Operators, of a common Eco-Efficiency Indicator, with a shared formula and the same methodologies to be used for traffic and energy consumption measurements. In this way, being its different values really comparable, the Indicator could be used by the Financial Analysts as one of the official parameters for the evaluation/ranking of the Companies. Coming back to the Eco-Efficiency Indicator of Telecom Italia, a possible evolution could be represented by its breaking down in two separate Indicators, one strictly related to the fixed network, and the other to the mobile one. Currently, this scenario encounters some difficulties, due to the presence of mobile core network routers and switches inside the Central Office: in this case, the electrical power consumption detected is not split in different shares for different equipments, being generically related to the Central Office at all. Therefore, at the moment, the OPEX allocation among the single equipments could only be done “ex-post”, making use of appropriate drivers based, for example, on the nominal unit power consumption. Staying on the same context, another possible next step could be represented by the Indicator’s breaking down pushed up to the single services. In this way, for example, we could expect to have: • an ADSL Eco-Efficiency Indicator that should grow primarily thanks to the traffic boost; • a VDSL Indicator rising thanks to both the numerator and the contemporaneous power savings (due to the progressive reach of the technological maturity); • a POTS Indicator, on the other side, increasing more in relation with specific optimization actions (e.g. compacting of commutation modules or switch-off of obsolete plants and equipments).
IV. CONCLUSIONS In recent years, the theme of power consumption has assumed an increasingly worldwide relevance: this aspect is particularly critical in the context of a Telecommunication Incumbent Company, which certainly represents one of the top energy consumers in its Country. To this end, concerning Telecom Italia, several action points are being implemented in order to reach significant power savings. On the other side, it must be underlined that the growth of the power consumption is mostly due to the progressive broadband penetration (started by the end of the nineties) that has allowed Telecom Italia to reach the relevant number of more than 7.000.000 ADSL lines. The above considerations have therefore originated in Telecom Italia the need for an Eco-Efficiency Indicator, which indicates, in a specific reference period, the ratio between the traffic (bit) processed by the fixed-mobile networks and the total power consumption (Joule) from the different sources. The values of the Indicator for the period 2003 – 2006 show a significant growth, mainly due to the ADSL penetration and to several power-saving actions launched by Telecom Italia. Since the last year, the Eco-Efficiency Indicator is officially reported within the annual Telecom Italia Sustainability Report and yearly targets are set. Several improvements can still be done, in order to gradually hone the calculation and possibly extend as much as possible its adoption. The indicator, measuring the eco-efficiency performance, helps companies towards the sustainability path. REFERENCES [1] United Nations, A Manual for the Preparers and Users of Eco-efficiency Indicators, vers.1.1, New York and Geneva, 2004 [2] World Business Council for Sustainable Development, Eco-efficiency. Creating more value with less impact, 2000 [3] http://www.swisscom.com/GHQGB05/content/Unser_Gewissen/Umwelt/ [4] Swisscom, Agreement on a significant eco-efficiency indicator for telecom operators [5] Telia Sonera, Energy index- a methodology of quantifying and analyzing energy efficiency in the ICT sector, 2006 [6] http://www.telecomitalia.com/cgibin/tiportale/TIPortale/ep/home.do?LANG=EN&tabId=3
