Quality of Service and Resource Utilization in 4G Long Term Evolution (LTE) Mobile Network

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1 Open Science Journal of Electrical and Electronic Engineering 2018; 5(6): Quality of Service and Resource Utilization in 4G Ayodeji James Bamisaye *, Adeola Abiola Adebayo Department of Electrical and Electronics Engineering, the Federal Polytechnic, Ado-Ekiti, Nigeria address * Corresponding author To cite this article Ayodeji James Bamisaye, Adeola Abiola Adebayo. Quality of Service and Resource Utilization in 4G Long Term Evolution (LTE) Mobile Network. Open Science Journal of Electrical and Electronic Engineering. Vol. 5, No. 6, 2018, pp Received: December 26, 2018; Accepted: January 23, 2019; Published: January 31, 2019 Abstract Quality of service and resource utilization are important factors in 4G LTE mobile network. LTE is deployed in the 700 MHz band, due to its propagation characteristics and spectrum depth, it has strong in-building penetration and internet assessment from any compatible device. This paper describes parameters of design methods that will integrate the waived techniques, downlink and uplink of LTE, its architecture and signal processing. The features of 4G LTE wireless communication makes it ideal to solve the problem associated with network capacity, speed, congestion, QoS among others. LTE will also provide unprecedented global coverage and inherent global mobility, speed to run bandwidth, Intensive applications, interoperable with existing mainstream cellular technologies, low latency to support real-time applications especially in developing countries. Keywords Broadband, Bandwidth, QoS, LTE, Capacity 1. Introduction Many of the rapidly growing internet applications and services are finding their way into the mobile wireless domain and taking advantage of the 4G system. Facilities such as real time streaming video, music and on-line interactive gaming are just few examples of facilities whose popularity is growing beyond expectations. Communication Technology has changed and mobile network application has increased. Mobile network and its data growth and the use of smartphone are creating extraordinary challenges for wireless service providers to conquer a global bandwidth shortage [1]. Mobile generation generally refers to change in the technology and nature of the service, the first was the move from analogue 1G to digital 2G transmission [2]. 3G allow network operators to offer users a wider range of advanced services while attain greater network capacity through improve spectral efficiency. It makes use of wireless voice telephony, video calls, and broadband wireless data, all in one mobile environment [3]. 4G is fundamentally the extension of 3G technology with improved bandwidth and speed. The prospect from 4G technology is high speed internet connection and high reliable voice quality. The word MAGIC also refers to 4G wireless technology which stands for Mobile multimedia, Anywhere Global mobility solutions over, Integrated wireless and Customized services. [1, 2] Development of the fourth generation (4G) systems accommodate the QoS and rate requirements set by applications like wireless broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB), minimal services like voice and data, and other services that utilize bandwidth [4]. An existing communication networks may be upgraded by A 4G system and is expected to provide a comprehensive and also secure IP based solution where services such as voice, data and streamed multimedia will be provided to users on an "Anytime, Anywhere" basis and at much higher data rates and good system service reliability compared to previous generations [5]. Long Term Evolution (LTE) evolves from the third generation technology which is based on WCDMA and defines the long term evolution of the 3GPP UMTS/HSPA cellular technology. The specifications of which are formally known as the evolved UMTS terrestrial radio access (E- UTRA) and evolved UMTS terrestrial radio access network

2 71 Ayodeji James Bamisaye and Adeola Abiola Adebayo: Quality of Service and Resource Utilization in 4G (E-UTRAN), commonly referred to by the 3GPP project LTE. It offers higher data rates, lower latency and greater spectral efficiency than previous technologies [5, 6]. LTE supports high performance mobile access functionality up to 350Km/h with 500Km/h. Peak data rates range from 100 to 326.4Mbps on the downlink and 50 to 86.4 Mbps on the uplink depending on the antenna configuration and depth of modulation. LTE is compatible with HSPA, UMTS and GSM-based technologies and therefore offers a modest evolutionary path for all existing GSM and HSPA operators. However, LTE complementary core network also offers the ability to support the handover of services [7]. LTE has been developed to offer both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes, allowing TD-SCDMA networks to also make a smooth transition to TDD LTE. Definitely, a combined FDD and TDD LTE deployment is expected to produce a broad foothold in many markets [2]. 2. System Design Techniques Irrespective of the actual technology, the future generation will integrate the foregone techniques and seeking development, with the parameters of design methods describe below: 2.1. Coverage In Figure 1, 2G was focused on full coverage for cellular systems and 3G provides its services in dedicated areas and introduces the concept of vertical handover through the coupling with wireless local area network (WLAN) systems, 4G focuses its own service in even smaller area and will be a convergence platform extended to all the network layers. Hence, the user will be connected almost anywhere due to the exploitation of the various networks available. Figure 1. Coverage range evolution from 2G to 4G.

3 Open Science Journal of Electrical and Electronic Engineering 2018; 5(6): Radio Environment Due to the tremendously rapid increase of number of users during the fast development of mobile communication and to avoid increasingly crowd relatively low radio frequency, 4G can adopt higher frequency to obtain a much wider user bandwidth, which is around 3G to 5GHz Spectrum Resource sharing among the various networks available will smooth the problem related to the spectrum limitations relative to 3G. The bandwidth of each channel is between 5MHz to 10MHz. One of the main requirements for accessing these frequencies is that of being able to coexist with other users of the band. This often implies that instantaneous access may not always be available when LTE- U is being implemented with different power levels allowed which is dependent upon the country and the area of the band being used. [8] 2.4. Services It is easy to see the migration of service types from 1G to 3G. Following this tendency, 4G provides high speed, high capacity, low cost per bit, IP based services for video, data and Voice (VoIP) Technology The 3G cellular standards such as UMTS (Universal Mobile Telecommunications System), WCDMA (Wideband Code Division Multiple Access) and EV-DO (Evolution Data Only) are looking increasingly obsolete, although years before it has achieved noticeable progresses. These technologies are threatened by the obvious superiority of BWA technologies such as WiMAX and FLASH-OFDM (Orthogonal Frequency Division Multiplexing). WiMAX is based on OFDM technology and Multiple-Input, Multiple- Output (MIMO) smart antenna technology which is best suitable for 4G. For areas already adopted 4G system, a genuine proportional fair scheduling algorithm could be invented to get load balancing over the cooperating transmission points [9]. Layer mapping and sorted SINR will produce better spectral efficiency [10] Network Security In the current mobile networks, operators are in complete control of radio access and backhaul, but this changes with 4G as that architecture allows for all-ip backhaul and multiple access networks due to increased risks of security intrusion and attacks. Security and privacy become more and more important as services touch more of commercial aspects, and thus accountability is required but not to the point of compromising identity. On the untrusted backbone of IP networks, users will need more end-to-end security achieved through efficient techniques as well as encryption of content and stored data. As the environment becomes more complex with a variety of services at subscribers' disposal, data protection and extra authentication will even be more important. Also critical will be location privacy, protection against attacks like malicious calls, eavesdropping, and traffic deviation re-routing [11]. 3. Features Description The following features of 4G wireless communication makes it ideal to solve the problem associated with network capacity, speed, congestion, QoS among others [12]: i. High Speed and High Quality Transmission: Max rate Mbit/s, Asymmetric Up/Down link speeds, QoS mechanism, Low bit cost, Smooth handoff across heterogeneous networks among others. ii. Flexible and Varied Service Functions: Support interactive multimedia, voice, video, wireless internet and other broadband service. Inter-network mobility management and authentication, Ad-hoc networking, Agent function, etc. iii. Open Platform: User can freely select protocols, applications and networks. Location and charging information can be used among networks and among applications. Improved security measures enabling wide functional range. iv. A spectrally efficient system (in bits/s/hz and bits/s/hz/site). v. High network capacity: more simultaneous users per cell. vi. An all IP, packet switched network. Table 1 shows conceivable parameters of 4G mobile communication system Parameter Key requirement Network Architecture IP Frequency band Bandwidth Data rate Access Technology Switching design Mobile Top speed Component design Modulation scheme Table 1. Parameters of 4G. 4. LTE Architecture 4G Data and voice coverage over IP Wireless LAN and WAN All IP (IPV6) Higher frequency bands 2-8GHz 5-20MHz Up to 20 Mbps OFDM (TDMA) Packet switched 200Km/s Smart antenna 64 QAM LTE and SAE (System Architecture Evolution) comes hand in hand, an evolution of the Core Network towards a flat, packet only, all-ip based architecture. In SAE, the network is composed of only two node types, the Base Station or enodeb (evolved NodeB) and the AGW (Access Gateway). This architecture enhancement reduces the latency of the network (in the range of 10-20msec round trip, an improvement of % when compared to the most advanced 3G networks), required to provide real-time

4 73 Ayodeji James Bamisaye and Adeola Abiola Adebayo: Quality of Service and Resource Utilization in 4G applications, like VoIP or on-line interactive gaming. An LTE network consists of the network elements enodeb (or Base Station, part of E-UTRAN) and Access Gateway to support control and user plane access to LTE User Equipment (i.e., wireless devices). Access Gateway functionality is supported by the Mobility Management Entity (MME) to manage the control plane, the Serving Gateway (SGW) for the user plane, and the PDN Gateway for access to the Internet [13]. EPC nodes are also connected to legacy systems (GERAN and UTRAN) so that LTE systems can co-exist with existing access technologies and facilitate seamless handovers (Figure 2). The SGW halts user plane access for the enodeb, performs accounting and monitoring of user data, routes user plane traffic and acts as a local mobility anchor point for handovers. The handover procedure of the LTE can be changed in the future. Now, LTE only supports hard handover which the UE breaks its connection with the source cell before connecting to the target cell. Nevertheless, with the introduction of CoMP, a UE can equally connect to multiple cells. In this regard, soft handover dure can be defined in the LTE requirement. Since there is difference between soft handover procedure and hard handover procedure, different mobility robustness optimization solutions can be considered. [14]. An SGW platform requires many capabilities including: i. Optimization for Packet (Bearer Plane) Processing: Since the SGW is designed to do user plane functionality for higher bandwidth systems, the platform on which the SGW resides should be optimized for packet processing. ii. Deep Packet Inspection (DPI): An SGW requires DPI capability from the platform to support lawful intercept, policy control, and QoS enforcement to manage access to services and available bit rate during times of congestion. DPI can also support functions such as targeted advertising. iii. Carrier-Grade Reliability: A field-proven, highlyavailable architecture is needed to eliminate data/control PDU loss with no switch-over delay. iv. Computing Power: An SGW platform needs substantial compute power for the control plane signalling between MME, SGSN, and PGW. v. Scalability: An SGW platform should be scalable so that capacity may be increased easily and robust enough to handle high load conditions. In addition, it should also be possible to co-locate functions in a single shelf (i.e., a single chassis may contain both MME and SGW functions). vi. Quality of Service (QoS): QoS can be included as part of the DPI service control and enforcement functions. vii. IP Security, Threat Management & Intrusion Detection/Prevention: Being part of an all-ip LTE network node, the SGW requires these security-related functionalities. Because mobile users are expected to hold carriers responsible for security breaches (much more than users on wire line broadband connections), it is vital for wireless operators to ensure that subscribers are protected from malware reaching their handsets. LTE network is less complex than current 3G technologies. Evolved UMTS networks have a clear objective to integrate all applications over a simplified and common architecture. The main components of LTE architecture are: a. A packet-optimized Access Network which can efficiently support IP-based non real time services as well as circuit-like services requiring constant delay and constant bit rate transmission. b. A simplified Core Network, composed of only one packet domain, supporting all PS services (possibly IMS-based) and inter-working capabilities towards traditional PSTN. Figure 2. Basic LTE Network Architecture.

5 Open Science Journal of Electrical and Electronic Engineering 2018; 5(6): Downlink and Uplink of LTE 5.1. Downlink of LTE multi user MIMO for enhancing the cell throughput Uplink of LTE LTE make use of OFDM for the downlink that is, from the base station to the terminal. OFDM and LTE requirements are comparable for spectrum flexibility and enables cost-efficiency for very wide carriers with high peak rates. It is a well-established technology. In the time domain there is a radio frame that is 10 ms long and consists of 10 sub frames of 1ms each. Every sub frame consists of 2 slots where each slot is 0.5ms. The subcarrier spacing in the frequency domain is 15 khz. Twelve of these subcarriers together (per slot) is called a resource block so one resource block is180khz. 6 Resource blocks fit in a carrier of 1.4 MHz and 100 resource blocks fit in a carrier of 20MHz [15]. There are three different physical channels in the downlink. The Physical Downlink Shared Channel (PDSCH) is employed for all the data transmission, the Physical Multicast Channel (PMCH) is used for broadcast transmission where a Single Frequency Network and the Physical Broadcast Channel (PBCH) is used transmit most significant system information within the cell. PDSCH are QPSK, 16QAM and 64QAM are Supported modulation formats. For MIMO operation, a distinction is made between single user MIMO, for enhancing one user's data throughput, and Table 2. Uplink downlink comparison. In the uplink, LTE uses a pre-coded version of OFDM called Single Carrier Frequency Division Multiple Access (SC-FDMA). This is to make up for a drawback with normal OFDM, which has a very high peak-to-average power ratio (PAPR). High PAPR needs expensive and inefficient power amplifiers with high requirements on linearity, which in turn increases the cost of the terminal and drains the battery faster. SC-FDMA resolves this problem by grouping together the resource blocks in such a way that reduces the need for linearity and power consumption in the power amplifier. A low PAPR also improves coverage and the cell-edge performance [16]. In the uplink there are two physical channels. While the Physical Random Access Channel (PRACH) is only used for initial access and when the UE is not uplink synchronized, all the data is being send on the Physical Uplink Shared Channel (PUSCH). Supported modulation formats on the uplink data channel are QPSK, 16QAM and 64QAM. The data rate in the uplink direction can be increased depending on the number of antennas at the base station if virtual MIMO / Spatial division multiple access (SDMA) is introduced. Due to this technology more than one mobile can reuse the same resources. TECHNOLOGY Peak Up Link Data Rate Peak Down Link Data Rate GSM 9.6mbps 9.6 mbps GPRS 20 mbps 40 mbps EDGE 60 mbps 120 mbps WCDMA 64 mbps 384 mbps HSDPA 384 mbps 10 mbps HSUPA 1.4 mbps 10 mbps LTE 50 mbps 100mbps With such higher data rates, 3GPP LTE specifications requires complex signal processing techniques such as multiple input, multiple-output (MIMO) along with new radio modulation technologies like orthogonal frequencydivision multiple access (OFDMA) and multicarrier code division multiple access (MC-CDMA). 6. Signal Processing in LTE As mentioned the uplink uses OFDMA and the downlink single-carrier frequency-division multiple access (SCFDMA). Both frequency-division techniques employ fast Fourier transforms (FFTs) to segment the allocated bandwidth into smaller units that can be shared amongst the users. SC-FDMA is used to reduce power consumption in the hands as the peak to average power ratio of SC-FDMA modulation is lower than that of OFDMA modulation. Also, from a computational standpoint, frequency division techniques scale more easily with bandwidth than code division systems, i.e., higher bandwidth CDMA systems require much more computational power than OFDMA systems. In addition, the use of different-sized FFTs support implementation across multiple bandwidths allocations including 1.25 MHz, 1.6 MHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, and 20MHz. Plus, the ability to use either paired or unpaired spectrum allocations, has the additional benefit of allowing operators to be much more flexible in the rollout of LTE systems as they can deploy in different sized bands depending on the available spectrum. While higher spectral efficiencies can be achieved via MIMO, it is also easier to implement MIMO in OFDMA systems than in CDMA systems, where noise is more uniformly spread. When combined with the other physical layer changes there should be a significant increase in the spectral efficiency of the system with the transition from CDMA to OFDMA. LTE-Advanced with Multi-Point Single- User MIMO is the next technique for further LTE-advanced [9, 10]

6 75 Ayodeji James Bamisaye and Adeola Abiola Adebayo: Quality of Service and Resource Utilization in 4G 7. LTE Performance LTE introduces a number of innovations that in aggregate, continue to push ever closer to the theoretical maximum data rates defined by Shannon s Law. Advances in multi-antenna techniques, OFDMA methods, wider bandwidth, and protocol efficiencies are fundamental to deliver the promise of 4G Mass Market Wireless Broadband. The amazingly high data rates and sector throughputs (capacity) per cell are fundamental to supplying the ever increasing demand for wireless broadband. LTE can be deployed in clear spectrum with bandwidth as wide as 20 MHz of paired spectrum (20MHz UL, 20 MHz DL). The high bandwidth of a single carrier radio will deliver unmatched economies when compared with multi-radio legacy approaches, and provides scope for significantly higher capacity compared to 3G-3.5G technologies camped to 5MHZ or smaller spectrum bandwidth [17]. Throughput capacity achieved by LTE is due to the following technical improvements: [18] i. The multiple antenna systems to increase overall data rate. ii. Better multi-path signal handling capability than CDMA technologies. iii. No intra-cell interference, as the sub-carriers are for a single user in a time slot. iv. Enhanced Interference cancellation is better for reduced inter cell interference. v. Mitigation of the cell shrinkage vs. loading phenomena of CDMA technologies. vi. More efficient Multicast, Broadcast. vii. Lowered and more efficient control overhead. viii. Frequency Selective scheduling for additional flexibility and efficiency. 8. LTE Services Through a combination of very high downlink and uplink transmission speeds, more flexible, efficient use of spectrum and reduced packet latency, LTE promises to enhance the delivery of mobile broadband services while adding exciting new value-added service possibilities. For consumers, LTE enriched user experience is typified by the large-scale streaming, downloading and sharing of video, music and rich multimedia content. All these services requires significantly greater throughput to provide adequate quality of service, particularly as future expectations of users will be increased by the growing popularity of other highbandwidth platforms like High Definition TV transmission. For business customers it will mean high-speed transfer of large files, high-quality video conferencing and secure nomadic access to corporate networks. Similarly, LTE brings the characteristics of today s Web 2.0 into the mobile space for the first time. Alongside secure e-commerce, this will span real-time peer-to-peer applications like multiplayer gaming and file sharing. In addition, Analysis considers a quite distinct set of services that do not have clear analogies in today s fixed network environment. These include machine to machine (M2M) applications and the large-scale exchange of information within community based projects. LTE is next-generation technology because LTE: i. Have the speed to run bandwidth. ii. Intensive applications. iii. Is the global mobile communication standard chosen by a majority of the world s leading carriers, which means opportunities for seamless roaming. iv. Is interoperable with existing mainstream cellular technologies. v. Has low latency to support real-time applications (average 30 ms end-to-end round trip delay). vi. Is highly secured. 9. Conclusion LTE will continue to change the wireless industry. Its high speeds and low latency enables it to run virtually any application designed for wired use on a mobile device. High definition video, Real-time video conferencing, Video telephony, Voice over IP (VoIP), Multi-player gaming and Mobile TV makes it ideal for improved wireless communication. 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