5G Technology Introduction

Background

A new generation of wireless communications is considered as the fourth stage of the revolution of the industry. This enables connectivity between different objects and machines throughout the world. In 1950’s and 1960’s, there was deployment of the first commercial analog mobile communication system with low penetration. The first generation mobile cellular standards were deployed in 1981 which are called analog standards. Then in 1991, the 2G Global system for mobile communications (GSM) network was deployed internationally which allows digital transmission and switching technology. This network provides improvement in quality of voice and capacity of network. It also provides supplementary services as Short message service (SMS) for sending the text information.

Fig. 1.1 Evolution of cellular standards

General packet radio services (GPRS) is an evolution of 2G known as 2.5G that provides packet-switched data services. There was further evolution of GSM in enhanced data rates for global evolution (EDGE).

CDMA was adopted by the European Telecommunications Standards Institute (ETSI) in two variants i.e. Wideband Code Division Multiple Access (WCDMA) and Time Division CDMA (TD-CDMA) and called it a Universal Mobile Telecommunication System (UMTS) which was the major 3G mobile communication system. The new specifications were developed by 3rd generation partnership project (3GPP) which is named as 3.5G. After that there were number of releases that signifies the evolution of 3G to 4G LTE.

In 2015, 4G networks were installed practically which are currently being deployed throughout the globe that provides data rated in 100Mbps for high mobility users and 1 Gbps for stationary users. But the demand for data rates of the order of many Gbps has been increasing due to increase in video traffic and ultra-high definition video streaming. This results in the introduction of 5G that will provide wireless networks to match data rates at very low delays. It is expected that 5G networks will be deployed around 2020. 5G expectations include; massive MIMO, full duplexing, device-to-device communications, caching, and mm-Wave communications. The system concept on integration of building blocks of advanced technology is the most decisive factor for the success of 5G. Only the evolution of current networks is not sufficient to meet the challenging requirements, but the revolution in both radio access network and the core network are needed. New physical layer technologies will be deployed in the radio access network such as massive multiple-input multiple-output (MIMO), non-orthogonal multiple access (NOMA), Full duplex (FD) communication, millimeter wave (mm Wave) communication, device-2-device (D2D) communication, and visible light communication (VLC). Following are the usage scenarios for IMT for 2020:

Enhanced Mobile Broadband: the volume of mobile data-traffic has been increased due to growth in the number of smartphones and other data-consuming devices coupled with enhanced multimedia applications. Around 2020, the delivery capacity of the networks needs to be increased to 100-1000 times due to increase in data traffic.

Massive machine-type communications: The interest in machine-to-machine communication and Internet of Things (IOT) will be increased in the coming years. Wireless networks will connect and manage billions of everyday objects. So, the major challenge of 5G network is to integrate human and machine-type traffic.

Ultra‐reliable and low‐latency communications: the performance metrics such as peak rate, coverage, spectral efficiency, and latency, will be enhanced in the 5G system to provide improved quality of service (QoS).

In particular, 5G will have:

  • Connectivity as a standard for people and things
  • Critical and massive machine connectivity
  • New spectrum bands and regulatory regimes
  • Network functions include mobility and security
  • Integration of content distribution
  • The network edge allows processing and storage
  • Software defined networking
  • Network function virtualization.

Cloud Radio Access Networks

To enhance the spectrum and energy efficiency of 5G networks, the cloud radio access network has emerged which is cost-efficient. There is a decoupling of radio functionality and baseband signal processing in C-RAN. In C-RAN, pool of baseband unit (BBU) placed in a cloud-based data center and a small cell comprises of a large number of remote radio heads (RRHs) which are having a low-cost. There are number of advantages of C-RAN architecture:

  • To provide on-demand services, spatial and temporal traffic fluctuations are adopted by C-RAN.
  • Implements cooperative strategies of transmission and reception.
  • Network upgradation and maintenance has been simplified.

User-centric networks

The radio access network must be redesigned to achieve the vision of 5G. So, the

main focus is to provide user-centric network rather than a cell-centric network. There

are following key properties of UCN:

  • Uniform access and seamless mobility should be supported by the network across conventional cell so that the target data-rates will be achieved by the users on demand.
  • To support diverse services and organize HetNet entities efficiently and effectively respectively, there will be distribution of the network functions over different radio radio network entities. On service demand, a complete set of network functions is provided by different entities of networks jointly.
  • To differentiate different services of the network and optimize experience of service, specific optimal network decisions should be provided by UCN. moreover, smart decisions about local cached traffic and traffic distribution and optimizations of service-specific RAN should also be made.
  • To optimize the network automatically with collected knowledge of the network, IT technologies can be borrowed so that low cost and high efficiency can be achieved by the network.

Challenges of CRAN towards 5G

There are two aspects of C-RAN i.e. the fronthaul (FH) issue and virtualization for

cloudification. A link between a BBU and an RRU is FH link. The common public

radio interface (CPRI) and the open base station architecture initiative (OBSAI) are

interfaces of FH. To connect BBU pool with remote RRUs, fibers are used in the

C-RAN with centralization. The number of fibers needed depends on the size of the

centralization scale. Realization of the cloudification feature is another challenge of

C-RAN. Virtualization technology is one of the keys to this goal. There is a need to

optimize and customize the virtualization technology and commercial off-the-shelf

(COTS) platforms in various aspects.

Security

The past four generations of wireless systems have one of the most important value offerings which is called security. The end-to-end security of newer generations of wireless systems must be improved. There will be increase in the use of mobile broadband for Internet access and cloud services and this will increase the vulnerability to attacks and the cost of damage caused. Large amounts of IoT data will be transmitted by 5G. Data or information-fusion may be used to extract sensitive knowledge. Hence, to prevent unlawful entry, connectivity to an Internet-connected household entry must be carefully audited. To provide the integrity and authenticity of the messages, appropriate security functions must be used.

5G use cases

  • Autonomous vehicle control

Autonomous driving of vehicles can be enabled using autonomous vehicle control. This may bring various benefits such as avoid accidents by providing better traffic safety, stress reduction and drivers will concentrate on other productive activities. Very low latency and high reliability will be provided for vehicle control signalling by installing vehicle-to-infrastructure, vehicle-to-vehicle, vehicle-to-people and vehicle-to-sensors communication on the roadside.

  • Emergency communication

To get rescued and survive in an emergency situation, the user should have a reliable network. This is needed in the case when some part of network has been damaged in disaster. Sometimes the damaged network is provided with temporary rescue nodes. Relaying functionality may be given to user devices to support other devices so that they can reach the operational network devices. Emergency communication has two main requirements i.e. high availability and energy efficiency.

  • Factory cell automation

To support life-critical applications cell automation has been used that consists of devices in assembly line and control units having high reliability and low latency.

  • High speed train

It becomes sufficient to provide high data rates in the high mobility trains that will become the major challenge for 5G.

  • Smart city

Many smarter urban inhabitant perspectives bring smart cities into reality. In coming years, people will be connected with their surrounding environments as they go from one place to another. To provide personalized, context and location-aware services, the smartness to life has been enabled by the connectivity.

  • Virtual and Augmented reality

Virtual reality is the ability of users to interact with others such as conferences, meetings, gaming and playing music. People will perform complicated tasks located remotely using virtual reality.

A live view of a physical, real-world environment is called augmented reality in which computer‐generated sensory input augments the elements.

  • Implicit communications

In future, there will be a drastic change in the way of communicating within social communities and individual groups. A 3D camera and intelligent image recognition technologies are consisted in a mobile phone along with different types of sensors that will capture the surroundings and provide context‐aware and location‐based information. In coming years, implicit communication will be used based on pre‐defined profiles without pressing any keys.

General requirements and key performance indicators

  • Capacity requirements

It has been projected by many forecasters that there will be upto 24-fold growth of mobile data traffic in the recent years. Moreover, there will be more diversified services in the future. Wide range of services, ranging from small packet services to richer content services, will be provided over the mobile network. Moreover, there is high

  • User-data requirements

The main aim of 5G is to provide high data-rate, and more uniform experience quality as compared to LTE due to rapid increase in trends towards richer content and cloud services. There is a target of improvement upto 10-folds in peak data-rates.

  • Latency requirements
    1. User-plane latency

The user plane latency in LTE is around 10 msec. Core-network delay components are included in the end-to-end user-plane latency. By reducing the latency related to processing delays, TTI duration, HARQ delays, and transport and core network, the end-to-end latency can be reduced.

  1. Control-plane latency

The requirement for control plane latency in LTE is 100 msec. Idle-to-connected and dormant-to-active latency are two classifications of control-plane latency.

    1. Idle-to-connected latency: It takes less than 50 msec for idle-to-connected state transition for LTE Release 10 and beyond. Due to reduction in UE processing time and request setup handling of RRC and NAS, idle-to-connected latency needs to be improved.
    2. Dormant‐to‐active: When the UE is already synchronized, the transition occurs between states is dormant-to-active. It is faster and takes only 9.5 msec. In order to enable future cloud services, 5G has to provide end-to-end latency of less than 5 msec along with higher data-rates. The requirements for TTI duration, HARQ signaling, transport and core latency, and network architecture will be evolved to a new level to achieve that level of end-to-end latency. The emergency warning deliver time should also be improved for better results.
  1. Massive device connectivity

The mobile operators will offer a greater range of services and every user is provided with a mobile smart life and to achieve this they have to expand their business in 2020 and beyond. There will be a need for more diversified cloud services by operators. Along with voice and data services, various new added‐value cloud services will be created by collaborating network and mobile terminals such as real‐time interactive services, data storage and processing, and others. For this connectivity to large number of devices will be provided. Moreover, in highly dense areas also, 5G will have to support all the services. It is believed that the number of simultaneously connected users will increase to 100-fold and 5G will have to achieve that target.

  • Energy saving and robustness against emergencies

The total energy consumption of 5G should be less as compared to that of current systems so that the system will be more sustainable and provide longer battery life. Even in case of natural disasters, lifeline communications should be provided by the system. There will be increase in capacity per unit network cost in case of 5G so that the system will be energy efficient.

The first phase of 5G specifications in Release-15 will be completed by March 2019, to accommodate early commercial deployment.

The second phase in Release-16 will be completed by March 2020, for submission to the ITU as a candidate IMT-2020 technology.

Fig. 1.2. 5G performance targets


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