SUNYIT. Reaction Paper. Comparison of Energy Efficiency in PSTN and VoIP Systems. SUBMITTED BY : Sanjeevakumar

Transcription

1 SUNYIT Reaction Paper Comparison of Energy Efficiency in PSTN and VoIP Systems SUBMITTED BY : Sanjeevakumar 11/14/2013

2 The paper is focused on the energy consumptions of the PSTN and VoIP systems. In order to analyse this they have used experiments and found out that VoIP was consuming more energy than the traditional PSTN networks. The authors describe the need to be energy efficient in order to cut down levels of CO2 emission. Earlier studies with relation to the energy have been done with copper and fibre based systems but they were analysed theoretically. The paper discusses on why VoIP has become popular over PSTN such as providing more functionalities and reduction of operational as data and voice share same lines. The paper focuses to find out if the popular VoIP systems which are said to be cost effective are to replace the PSTN system, can do so without increasing the operative cost due to higher energy consumption. The authors use their campus PSTN and VoIP systems as their models. Both these systems are to be compared by the real time power consumption data. Then the factors which are causing the energy loss are identified and consumption models are designed for both systems to find out the per user consumption. The authors then give a description of the PSTN network which they are using in this experiment which consists of 14 PBXs serving 3120 phones. The VoIP system has 4 power over Ethernet switches 3 of them having 24 ports and one having 48 ports along with a PC running asterisk software. This system allowed 120 users with the ability to make phone calls and also use data services. The VoIP architecture utilized shared infrastructure of Ethernet that provides data services with a good option in terms of energy is saving. To calculate the power consumption a mathematical model is extrapolated P (PBX) + X P (lc) + K P( ph) = PTOT(PBX) Here the P (PBX) is the minimum constant PBX power consumption Power consumed by lie cards is given by P(lc) and P(ph) X and K represent respectively the number of line cards and phone lines connected to PBX

3 Using the above equation they developed two equations based on the interfaces and then calculated the values for the P(PBX) and P(lc) by adding 10 new lines to find out the effect of energy consumption on PBX. From the graph we can see that when they added 10 new lines the power consumption grew from around 181 to about 187 Watts. For the VoIP system again a mathematical formula is derived Psw + K1 Ppoe + K2 Ppoe= Ptot (VoIP) Psw is minimum constant power consumption of Ethernet switch. K1 and K2 represent number of poe and non poe phones. An assumption that non poe phones do not require power from switches hence Ppoe is ~0.Again we get two equations from which we solve to find out the Psw and Ppoe. This was repeated with the other switches to verify the results. Then the results were used to analyse both the architectures. A formula which provides a rough estimate of the power consumption values for a generic PSTN system is computed Ppstn = N(t lines) / (Nusers/pbx) * Ppbx + Nlines*Pph Nlines is the number of phone lines and Nusers/pbx is the number of phones a PBX can host. Similarly for the VoIP system we have P voip = Nlines / N(ports/switch) * Psw + Ntlines* Ppoe Nports/switches is the number of ports available per specific switch. The results are put into a graph from where some of the following conclusions are made. VoIP seems to consume more power for the considered architecture but it strongly depends on the devices used for implementing the phone infrastructure. But there is a possibility of making the system efficient by adding energy wise schemes. One way to execute this would be to put the VoIP phones in sleep when not in use. The author then explains four scenarios by which we can reduce the power consumption in the popular VoIP systems.

4 In scenario 1 using of an already deployed LAN system along with VoIP phones powered through Ethernet.This eliminates the need to ad and power up extra Ethernet switches Psw is 0. The power consumption then becomes Pvoip1 = N tlines *Ppoe Scenario 2 describes use of the sleep mode to reduce power when no user is present. Here the power consumption is given by Pvoip2 = P voip(8/24)(5/7) The 8/24 indicates the number of working hours in a day and 5/7 indicates the number of working days in a week. Scenario 3 describes the combination of VoIP phones and already deployed internet connection with power saving scheme defined in the earlier scenario The power consumption is calculated to be P = P voip2(8/24)(5/7) In the final scenario the author discusses use of softphones which consume virtually zero power and an existing internet connection to set up voice communication.(psw=0 and Ppoe =0). The results are shown in the graph Results show that VoIP solutions are more energy expensive. Only when one of the scenarios is exhibited the consumption lowers. Scenario 3 shows a better energy consumption level than the others.

5 Conclusion and Thoughts The authors have concluded that VoIP is indeed more energy consuming than PSTN but the values could be having the effect of older technology in use. Hence they have said that they will continue work on this topic where they will analyse analog and digital phones with relation to the energy consumption and compare them with the newer generation PBX and switches. As of now they are working on the AASTRA s new generation PBX which have replaced the earlier PBX in their college. Considering the conclusion of this project it seems that we have to analyse how energy consumption levels are with the latest technology available. With newer technology becoming much faster in processing and transferring data at very high speeds we will be able to see some difference in what this paper has discussed. I feel the authors have chosen a very good topic to discuss with relation to VoIP. VoIP is becoming more popular and major organisations are implementing it and thus the need to know VoIP system energy consumption levels is significant. As global warming is already on the rise newer technology should try to reduce it and not enhance it. In the beginning of the paper they authors describe of the problems which occur due to higher needs of energy some of them being more CO2 released. Hence this topic is one which has to be experimented on from time to time to understand how newer technology is affecting energy consumption levels. Communication will never stop and hence it is necessary to introduce energy efficient systems. This project can even be implemented in SUNYIT provided we have a VoIP system setup along. We already have the PSTN network so we can carry out the project. However the age of the technology available at SUNYIT will play a major role in our results as this paper suggests that newer technology could prove VoIP to be more efficient. We can extend this project by including other factors which are affecting the power consumption such as the fans and lights in the switches etc.