Power System Maha Butt Department of Computer Science,

Power Optimization in 5thGeneration of Wireless Communication SystemMaha ButtDepartment of Computer Science, BahriaUniversityIslamabad Campus, [email protected]

com Abstract— In the past few decades mobile wireless technologyhas experience of various generation of technology revolution & evolution,namely from 0G to 4G. An advance implementation of 5G technology which arebeing made on the development of World Wide Wireless Web (WWW). The mainpurpose of this paper is to highlight and compare the 3G, 4G and 5G networks interms of energy efficiency.

In current era, energy efficiency has become amatter of key importance for 5G wireless network. So there is a need to useenergy-efficient architecture to meet the demands of increased capacity, animproved data rate and the better quality of service of the next-generationsnetworks.  Keywords— 3G,4G, 5G, Energy EfficiencyI.      IntroductionA wireless communication or simply wireless system is the exchange ofinformation between different nodes that are not connected by physical cables.Most common wireless systems use radio waves for information transfer. This isalternative of physical medium such as, fiber-optic and coaxial cables, whichare more expensive. Today mobile networks are primary need of everyone. Peoplewithin a city, country, inter-continental or even across the world connectedthrough wireless networks, which leads to congestion of network, lowconnectivity speed and low bandwidth.

Without wireless network easy personalcommunication is not possible 1.The successor of 1G, 2G is 3G. The thirdgeneration (3G) came into practice in 2000, which provided transmissionrate up to 2Mbps along with improvement in QoS. 3G technology offered users awide range of advanced services including web based applications, audio andvideo files. To support multimedia applications 3G had to deliverpacket-switched data with better spectral efficiency, at far greater speed. Themain disadvantage of 3G mobile phones was that they require more power thanmost 2G models 2.

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Fourth generation (4G) is the successor of 3G withthe extension of bandwidth and services offer in 3G. 4G offers a speed of 100Mbpswith premium quality and high security. The main discriminate factors between3G and 4G are data rates, way of transmission, access technology to theinternet, QoS and security. But the problem is that energy consumption isgrowing even more with the development of 4G system worldwide 1, 3.Next to 4G is 5G (5th generation),which leads to excellence of wireless communication in mobile technology. 5Gwill provide all previous features with better response like bandwidth,spectral efficiency, energy efficiency etc 4.

With the development of 4G networkworldwide, energy consumption is growing even more which is very dangerous foruser health. High power emitted by handsets while in use tends to harm the userin close proximity. So there is need to adopt energy efficient architecturewhich will also satisfy the user’s demand of battery life.

Energy efficiency istraditionally defined as the computation of number of bits transmitted per jouleof energy consumed 3.  Fig 1. Evolution of 1Gto 5G technology    Remainingpart of the research paper is organized as, Section II presents LiteratureReview, Section III presents discussion and comparison of different approaches,Finally paper is concluded in the last section IV. II.LITERATURE REVIEW     The Following table shows different poweroptimization method which are used in different generations with their pros andcons. Like sleep mode of BS and use of relays method is used in 3G for poweroptimization. “Base Stations(BSs) consume 60-70% of the total networkenergy”5. Thus, reducing power consumption rate of BSs plays vital rolein green communication.

Enabling sleep mode in BS as shown in fig. 2,usually different BSs need to cooperate to each other. A BS controller (BSC) isused to exchange traffic between these BSs If some BS are at sleep, theyrelease their channel resources to active neighbour BSs, while these active BSsuse such resources to provide wide range of coverage to the mobile users locatednearby to sleeping BSs 6. Table 1: Power Optimization method in3G, 4G & 5G      Sr.No   Technology   Power Optimization Method   Pros   Cons 1   3G   Sleep mode of BS & use of Relays ·          Low implementation cost. ·          No need to modify current structure of cellular network.

·          Blocking events might occur due to insufficient available capacity in active BS. ·          Implementing RSs in the network introduces other costs.   2   4G   BS energy saving, use of relays and small cells.

·          By using Small Cells, no need to deploy additional expensive macro base stations usually hard to install in dense urban areas. ·          Deployment of Small cells requires minimum changes in the current standard and can save a lot of user’s battery consumption.           ————   3   5G   Use of Small cells, Relays with SCA and D2D communication, SWIPT, C-RAN.   ·          By using these technologies energy will be saved up to 35%     ————     Fig 2.

Cell zooming Technique (a) Always ON configuration (b) Analyzingphase (Possibility of BS sleep mode) (c) Final configurationwith cell zooming and sleep mode Without changing the current structures of cellularnetwork, another way of improving energy efficiency of BSs is the use of lowpower relay stations (RSs). By adding RSs in the   network, broadcast power can be saveddue to diminished distances between transmitter receiver pairs 5. A Cellularnetwork using Relay stations is shown in fig. 3.

  Fig 3. Relay aided Cellular network Anothermethod is Use of small cell as shown in fig. 4, which is used in 4G forpower optimization. Small cells are basically small base stations that divide acell site into abundant smaller pieces, and it is a term that includes picocells, micro cells, femtocells and can cover indoor/outdoor systems.  Themain purpose of small cells is to enhance the macro cell’s data capacity, overallnetwork efficiency and speed. Small cells are usually used in very inhabited areas,such as train stations, shopping malls, sports places and airports – in short,any place where a lot of people using data at a time from the same given point.

  Fig 4. Macro-Femto Cell Deployment In 5G, some moderntechnologies are added with previous like use of Relays with Small Cell AccessPoint (SCA) and D2D Communication. Relay in thecompany of small cell is Crucial. Base station firstly connects with relay node,which then communicates with specific SCA of the building, where Mobile Station(MS) is placed inside of that building.Device-to-Device(D2D) communication plays a vital role in enhancing the EE of the cellularnetwork. It maintains the reliability of the connection among the users, byestablishing direct connection and latency reduction.

Traffic divesting onthe direct connection minimizes the load on the BS, and helps the BS to convertin sleep mode. 7To meet the highdemand of EE, the most emerging technology is Wireless Power transfer (WPT). Byusing this technology nodes charge their batteries from electromagnetic   radiations. Thecomponent used for this reason is Rectenna which transforms the microwave forceto direct current 3.Anothercomponent of 5G energy efficient architecture is cloud RAN (C-RAN). The mainpurpose of C-RAN is reducing the BS sites by using the centralized processing.Base station and small cell will be connected to the C-RAN which will diminishtransmission distance and it will lead to lower power consumption. It can also beturned off easily in no traffic hours to save power.

Hence C-RAN plays a vitalrole in Energy Efficiency 3.III.DISCUSSION AND COMPARISON     OF VARIOS APPROACHES    As we have discussed above, Base Stationsconsumes a huge amount of energy in cellular network. This energy consumptiondepends upon the mobile traffic in cell area (BS area), whichchanges from time to time, peak to low.

By considering this situation, atechnique named as Cell Area revision method (CAR) is used which changes thetransmission area of a cell according to real time network traffic. CAR is categorizedinto three methods: 8       I.           Cell Zooming Technique     II.           Macro-femto Cell deployment  III.           Relay deployment1)   Cell Zooming TechniqueThis technique is used in 3G and explainedwell in Fig. 2. It zoom-in or zoom-out cell area according to the mobiletraffic and the level of transmission power increases or decreases accordingly.

Power consumption model introducing sleep modes and cell zooming, reduces thepower consumption by up to 14.4% 8. Every technique has its pros and cons too, sohere are some advantages of Sleep mode technique. This technique is easier andless costly for tasting and implementation.

It requires no modification in currentstructure of cellular network. Some disadvantages are blocking events mightoccur due to insufficient available capacity in active BS. Trade-off betweenperformance and saving, current modelling not accurate enough.  2)   Macro-femto Cell deploymentThis technique is used in 4G with thecombination of previous techniques and explained well in Fig.

4. Femto cells areused to manage the mobile traffic when a BS is in sleep or power saving mode. Theyalso reduce the distance and transmit power between the user and BS especiallyin the indoor activities 8, 3. By using Small Cells, no need to install otherexpensive macro base stations which are usually hard to install in crowdedurban areas. Use of Small cells requires least changes in the current structureand can save a lot of user’s battery consumption.3)   Relay DeploymentRelays are primarily introduced to enhancethe coverage area of BS but later it was realized that relaying can be appliedto increase the throughput of the network as well as reduce the transmissionpower. The basic principle used in a relay assisted network is that mobilestation (MS) receive signals from both relay node (RN) as well as base station(BS) depending on which provides strong signals which generally depend on thedistance between them 5. Relays are used in 3G, 4G and 5G as well.

A relayaided network in explained well in Fig. 3.Plus point of use of Relays is RN splits thelonger path into shorter once by giving LOS communication and thus reducing theresulting total path loss.

This accordingly reduces the power needed fortransmission. One of the important points is that direct communication consumesless energy than using relays for shorter distance. Optimal placement of therelays plays an important role to optimize the power consumption of thenetwork. Energy efficienttechniques in 5G    5G is thecombination of energy harvesting technologies. Names of these technologies have been shown in table 1. Some of thesehave been discussed above. Now the most upcoming technology is Simultaneouswireless information and power transfer (SWIPT), where nodes charge theirbatteries from electromagnetic radiation.

As shown is Fig 5    Fig 5. Simultaneous wireless information and power transfer   In 5G network, avariation of MIMO is planned in which a very large number of antennas areemployed at the base station called Massive MIMO. Using this technology, thebase station can communicate with multiple users concurrently in the samefrequency band hence providing high multiplexing as well as array gain at thesame time.

Massive MIMO technology is not only spectrum efficient but energy efficientas well 3. EnergyEfficient architecture in 5G     The architecture includes the concepts ofSWIPT, massive MIMO and cloud RAN for improving EE in the next generationnetwork. The proposed architecture is shown in Fig 6. To represent the variousscenarios considered, we have taken different user equipment represented asclients in our architecture. C7, C8 and SCA2 directly communicate with the basestation due to line of sight path and good channel conditions between them.

C4,C5 and C6 are located indoors and hence send signal to SCA2 and not directly tothe base station. SCA2 as located in line of sight path of base station doesn’trequire a relay. But C9, C10 and C11 along with SCA1 are not in line of sightpath of the base station so require a relay for good reception as well as poweroptimization. The relay used can be mobile, fixed or UE relay. C1, C2 and C3 asshown communicate with SCA1 as they are located indoors. The SCA1 then communicates with the relay which inturn communicates with the base station. The relay node is chosen according torelay selection policy for power optimization.In ourarchitecture, we have considered different channel conditions including bothline of sight and non-line of sight paths as both have different path loss andhence will require different power from the base station to maintain therequired SNR for a particular application.

There can be four channel conditionswhich are without relay and without penetration   that is simpleline of sight path, without relay and with   penetration that is due to various obstaclespresent in the channel. Thirdly, there is with relay without penetration andlast is with relay with penetration which includes the path with relay as wellas includes effect of refection, refraction and diffraction through variousobstacles present in the atmosphere. Also, in the indoor communication as wellthere are expected to be two paths, i.

e., both line of sight and non-line ofsight paths exist indoors as well. This is due to presence of obstacles insidethe building as shown in our architecture.    Fig 6.

Proposed architecture for power optimization in 5G network.  Table 2: Energy saving by different techniques S.No. Techniques Energy Efficient 1 SWIPT 30% 2 Small Cells 11.1% 3 C-RAN 21.

2% 4 Massive MIMO 30.3 Mbit/J 5 Relays 9.7 dB power reduction   IV.

CONCLUSIONIn this paper,we have discussed the growing demand for energy efficiency in the nextgeneration networks. We have analysed the trends in the field of wirelesscommunications in the last decade which indicated a shift towards pursuing greencommunication for the next generation network. Wehave gone through the various techniques which can be used in the future foroptimizing the power of the network and the presented a summary of the workthat has already been done to improve energy efficiency of network using thesetechniques. A system model for EE improvement with the use of relay selectionhas also been described along with a comparison of various algorithms used forEE in relay based environments.  REFRENCES1 Olumuyiwa Oludare Fagbohun, “Comparativestudy on 3G,4G and 5G wireless technology”,IOSR journal of Electronics and Communication Engineering, Vol.

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