Rishika Naarayan
PES1UG22CS476
Section ‘H’
A Survey of 5G Network: Architecture and Emerging Technologies
Summary Report
INTRODUCTION:
Advancements in wireless communication, including HSPA, LTE, and emerging technologies
like spectrum access, higher frequencies, massive antennas, device-to-device
communication, and ultra-dense deployments, are shaping the future. Mobile
communication has evolved from analog voice calls to high-speed broadband services,
enabling new applications and increased network traffic. The vision for 2020 and beyond is a
networked society with ubiquitous access to information. To achieve this, new technologies
will integrate with existing ones, and while LTE, HSPA, and Wi-Fi will evolve, new
technologies may be needed for full realization.
EVOLUTION OF WIRELESS TECHNOLOGIES:
G. Marconi, an Italian inventor, made a significant breakthrough in wireless communication
by transmitting the letter 'S' over 3 kilometers using Morse code and electromagnetic waves.
This event marked the beginning of wireless communication, which has since become
integral to modern society. The evolution of wireless technology is depicted in Figure 1,
illustrating advancements in data rate, mobility, coverage, and spectral efficiency. The chart
shows that earlier generations like 1G and 2G used circuit switching, while 2.5G and 3G
employed both circuit and packet switching. Recent generations, from 3.5G to 5G,
predominantly use packet switching. Additionally, the chart distinguishes between licensed
spectrum used by evolving generations and unlicensed spectrum utilized by technologies like
WiFi, Bluetooth, and WiMAX.
An overview about the evolving wireless technologies is below:
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The first generation (1G) of mobile communication had a data rate of up to 2.4 kbps.
It was used by systems such as the Advanced Mobile Phone System (AMPS), Nordic
Mobile Telephone (NMT), and Total Access Communication System (TACS). However,
1G had several disadvantages, including limited capacity, inefficient handofss, poor
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voice quality, and lack of security. Voice calls were stored and played in radio towers,
making them vulnerable to eavesdropping by third parties.
The second generation (2G) of mobile communication used digital technology. The
Global Systems for Mobile communications (GSM) was the first 2G system, primarily
used for voice communication with a data rate of up to 64 kbps. 2G phones had
longer battery life due to low-power radio signals. 2G also introduced services like
Short Message Service (SMS) and email. Key technologies included GSM, Code
Division Multiple Access (CDMA), and IS-95.
2.5G cellular systems combine 2nd generation (2G) technology with enhancements
like General Packet Radio Services (GPRS). Unlike 2G or 1G networks, 2.5G systems
use both packet switching and circuit switching. They can achieve data rates up to
144 kbps. Key technologies of 2.5G include GPRS, Enhanced Data Rate for GSM
Evolution (EDGE), and Code Division Multiple Access (CDMA) 2000.
The third generation (3G) of mobile communication ofsering transmission rates up to
2 Mbps. 3G systems provided high-speed mobile access to services based on Internet
Protocol (IP) and improved Quality of Service (QoS). Additional features like global
roaming and enhanced voice quality made 3G a significant advancement. However,
3G handsets required more power than most 2G models, and 3G network plans were
more expensive. 3G introduced technologies like Wideband Code Division Multiple
Access (WCDMA), Universal Mobile Telecommunications Systems (UMTS), and Code
Division Multiple Access (CDMA) 2000. Evolving technologies like High-Speed
Uplink/Downlink Packet Access (HSUPA/HSDPA) and Evolution-Data Optimized
(EVDO) led to an intermediate wireless generation between 3G and 4G called 3.5G,
ofsering improved data rates of 5-30 Mbps.
3.75G Long-Term Evolution (LTE) technology and Fixed Worldwide Interoperability for
Microwave Access (WiMAX) are considered the future of mobile data services. They
have the potential to enhance network capacity and provide many users access to
high-speed services such as on-demand video, peer-to-peer file sharing, and
advanced web services. Additionally, these technologies ofser operators access to
additional spectrum, allowing them to manage their networks more efficiently and
provide better coverage and performance at a lower cost.
4G, considered the successor to 3G and 2G standards, is being standardized by the
3rd Generation Partnership Project (3GPP) as Long-Term Evolution (LTE) Advanced,
along with Mobile Worldwide Interoperability for Microwave Access (WiMAX). 4G
systems aim to enhance communication networks by providing a comprehensive and
reliable IP-based solution. They ofser services like voice, data, and multimedia to
subscribers anytime and anywhere, at much higher data rates than previous
generations. Applications intended for 4G networks include Multimedia Messaging
Service (MMS), Digital Video Broadcasting (DVB), video chat, High-Definition TV
content, and mobile TV.
5G technology, with advanced access technologies like Beam Division Multiple Access
(BDMA) and Non-Orthogonal Multiple Access (NOMA), is set to replace 4G to meet
the increasing user demands. BDMA allocates orthogonal beams to each mobile
station and divides these beams based on mobile station locations, increasing system
capacity. The shift to 5G is driven by the need to address challenges not efsectively
handled by 4G, including higher capacity, data rates, and connectivity, lower latency,
reduced cost, and improved Quality of Experience (QoE) provisioning.
5G CELLULAR NETWORK ARCHITECTURE:
The architecture of a 5G cellular network includes advancements like Beam Division Multiple
Access (BDMA) and Massive Multiple Input Multiple Output (MIMO) technology to improve
capacity and coverage. There is a focus on separating indoor and outdoor setups to reduce
penetration losses and improve spectral efficiency. Technologies like WiFi, Small Cells, and
millimeter wave communications are used indoors. Outside, large antenna arrays are
deployed, connected to base stations via fiber optics, and mobile users are equipped with
multiple antenna units to form virtual massive MIMO links. Mobile small cells are used for
high-mobility users like those in cars and trains. The network architecture consists of radio
network components and a network cloud with User Plane Entity (UPE) and Control Plane
Entity (CPE) for higher-layer functionalities. Network Function Virtualization (NFV) is used for
resource pooling and service provisioning. This proposed architecture provides a platform
for future 5G standardization but requires addressing several issues.
EMERGING TECHNOLOGIES FOR 5G WIRELESS NETWORKS
The exponential growth of mobile and wireless traffic, driven by the increasing number of
connected devices, presents challenges that 5G aims to address. By 2020, an estimated 50
billion devices will be connected to the cloud, requiring increased capacity, improved energy
efficiency, reduced costs, and better spectrum utilization. The technical aim of 5G is to
support a system that provides 1000 times increased data volume per area, 10 to 100 times
more connected devices, 10 to 100 times higher user data rates, 10 times longer battery life
for low-power devices, and 5 times reduced end-to-end latency. Key technologies for 5G
include new transmission waveforms, multiple access control, massive MIMO, advanced
network coordination, multi-hop technologies, spectrum extension, and efficient
interference management. Specific technologies like Device-to-Device (D2D)
communications, Massive Machine Communications (MMC), Moving Networks (MN), Ultradense Networks (UDN), and Ultra-reliable Networks (URN) will play crucial roles in achieving
these goals and shaping future wireless standards.
MASSIVE MIMO
(Multiple Input, Multiple Output) is an advanced technology that uses arrays of antennas,
typically hundreds, at base stations to serve multiple user terminals simultaneously in the
same time and frequency slot. It aims to extract the benefits of MIMO on a larger scale,
making next-generation networks more energy-efficient, robust, secure, and spectrumefficient. Massive MIMO relies on spatial multiplexing, which requires channel state
information from both uplink and downlink channels. In conventional MIMO systems, the
base station sends pilot waveforms to terminals for channel estimation, but this approach is
not viable for massive MIMO due to increased complexity and pilot signal overhead. Massive
MIMO systems often work in Time Division Duplexing (TDD) mode and rely on reciprocity
between uplink and downlink channels to reduce complexity and pilot signal overhead.
1. Massive MIMO can improve radiated energy efficiency by 100 times and increase
capacity by 10 times or more. This improvement is due to the spatial multiplexing
technique used in Massive MIMO systems, which concentrates energy in small
regions in space. The principle of coherent superposition of wave fronts ensures that
signals emitted from antennas add constructively at intended terminal locations and
destructively elsewhere. Zero forcing is used to suppress interference between
terminals, but at the cost of increased transmitted power. Maximum ratio combining
(MRC) is preferred over Zero forcing (ZF) due to its computational ease and
efsectiveness with large numbers of base station antennas. MRC reduces power
without significantly afsecting spectral efficiency or multiuser interference. This leads
to 10 times higher spectral efficiency compared to conventional MIMO systems, as
more terminals are served concurrently in the same time-frequency resource.
2. Massive MIMO systems use low-power, cost-efsective components, unlike
conventional systems. They employ hundreds of inexpensive amplifiers with milliwatt
output power, eliminating the need for large coaxial cables. This approach reduces
costs significantly. Massive MIMO averages noise, fading, and hardware deficits by
combining signals from many antennas, increasing robustness. The system's excess
degrees of freedom allow for efficient signal shaping, enabling each antenna to
transmit signals with small peak-to-average ratios and constant envelopes at a
modest increase in total radiated power. This efficiency reduces power consumption,
making it feasible to power base stations with renewable resources. Additionally,
Massive MIMO significantly reduces concerns regarding electromagnetic exposure.
3. Massive MIMO significantly reduces latency on the air interface, a key concern in
next-generation networks. Latency in wireless communication is often caused by
fading, where signals travel through multiple paths due to scattering, reflection, and
difsraction before reaching the terminal. This can lead to signal interference, reducing
signal strength and causing delays. Massive MIMO, with its large number of antennas
and beamforming capability, can avoid fading dips, reducing latency. This means that
latency cannot be further decreased with Massive MIMO.
4. Massive MIMO simplifies the multiple access layer by strengthening the channel and
making frequency domain scheduling inadequate. In Massive MIMO systems,
Orthogonal Frequency Division Multiplexing (OFDM) ensures that each subcarrier
has nearly the same channel gain. This allows each terminal to be allocated the full
bandwidth, reducing the need for extensive physical layer control signaling.
5. Massive MIMO strengthens wireless systems against both unintended man-made
interference and intended jamming. It achieves this by utilizing multiple antennas to
improve robustness. Massive MIMO systems ofser an abundance of degrees of
freedom that can be leveraged to cancel signals from intended jammers. Additionally,
by using joint channel estimation and decoding, these systems can significantly
reduce the impact of intended jammers. From an information theoretic perspective,
massive MIMO systems can achieve the multiplexing gain of massive point-to-point
MIMO systems while mitigating issues caused by unfavorable propagation
environments.
INTERFERENCE MANAGEMENT
In cellular wireless communication systems is crucial for efficient resource utilization,
especially with the introduction of concepts like reuse and densification. One of the key
challenges is increased co-channel interference, particularly at cell boundaries, due to
network density and load. To address this, advanced interference management techniques
are essential, such as advanced receivers and joint scheduling.
a) Advanced Receiver: This technique involves detecting and decoding interference
symbols within the modulation constellation, coding scheme, and resource
allocation. By reconstructing and canceling interference signals from the received
signal, advanced receivers improve signal decoding performance. They can mitigate
both inter-cell and intra-cell interference, especially in systems with multiple
antennas like massive MIMO.
b) Joint Scheduling: In LTE-Advanced Release 10 and 11, joint scheduling has been
introduced to address interference management. It involves synchronized
transmission among multiple transmitters in difserent cell sites. Coordinated
multipoint schemes, including coordinated scheduling, coordinated beamforming,
and dynamic point selection, help improve performance, especially at cell edges.
Spectrum Sharing Techniques in 5G Networks:
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Distributed Spectrum Sharing Techniques:
Advantages: Efficient, local framework, manages interference efsectively.
Examples: Coexistence protocols, coexistence beacons (e.g., 802.22.1 standard), MAC
protocol adaptations (e.g., Bluetooth, WLAN).
Methods: Clear exchange of messages between systems, coexistence beacon-based
solutions, MAC protocol adaptations for horizontal coexistence.
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Centralized Spectrum Sharing Techniques:
Advantages: Ofsers reliability, certainty, and control.
Examples: Geo-location database method, spectrum broker approach.
Methods: Querying databases for available resources, negotiating with a central unit
for short-term spectrum grants.
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Future Innovations:
Cognitive Radio: Programmable wireless devices that dynamically adapt networking
protocols, spectrum utilization, channel access methods, and transmission
waveforms.
Benefits: Expected to revolutionize wireless communications, improve spectrum use,
and serve as a universal platform for wireless system expansion.
Challenges: Requires large-scale deployment, real-world experimental deployments
underway to overcome challenges and achieve better spectrum utilization [46].
Spectrum sharing techniques play a crucial role in 5G networks, enabling efficient use
of limited spectrum resources and supporting the future demands of mobile
broadband systems.
Device-to-Device (D2D) Communication in 5G:
Definition: Involves direct communication between devices, bypassing base stations.
Types:
1. Device Relaying with Base Station Controlled Link Formation: Devices at cell edges
relay through others for better service and battery life.
2. Direct Device-to-Device Communication with Base Station Controlled Link Formation:
Devices exchange data without base station involvement, but base station helps in
link formation.
3. Device Relaying with Device Controlled Link Formation: Devices synchronize
communication using relays without base station involvement.
4. Direct Device-to-Device Communication with Device Controlled Link Formation:
Devices communicate directly with each other, controlling link formation themselves.
Benefits: Improves service quality, extends battery life, and enhances network coverage,
particularly in congested areas or at cell edges.
Challenges: Requires addressing security and interference management issues due to data
routing through other users' devices.
 Device-to-device (D2D) communication in 5G networks involves security and
interference management challenges:
Security: Closed access allows trusted devices to communicate directly, ensuring privacy
with encryption. Open access, where any device can act as a relay, requires further research
for secure communication.
Interference Management: Base stations can manage interference in some D2D scenarios,
but decentralized methods are needed for others. Algorithms like resource pooling and noncooperative games can help allocate resources efsectively.
Relays: Relays are vital for extending communication range or improving link quality. They
play a crucial role in scenarios where direct communication is challenging.
These aspects are critical for optimizing D2D communication and ensuring efficient use of
spectrum in 5G networks.
Network Model:
A device-to-device (D2D) enabled cellular network includes multiple relays to extend
communication range or improve link quality. Relays are used for scheduling and resource
allocation when direct communication between devices is challenging. Relays can assist both
cellular and D2D user equipment and are denoted by a set L. User equipment assisted by a
relay is denoted by U, where U` ⊆ {C ∪ D}, representing both cellular (C) and D2D (D) user
equipment. In scenarios where multiple relays communicate with related D2D user
equipment, relays help reduce the computational load at the eNodeB.
Radio Propagation Model:
The propagation channel includes distance-dependent path loss, shadow fading, and
Rayleigh fading. Path loss equations describe the link between user equipment and relay,
and between relay and eNodeB. The link gain between any pair of network nodes can be
calculated based on the path loss equation.
Realizable Data Rate:
The unit power Signal-to-Interference-plus-Noise Ratio (SINR) for the link between user
equipment and relay, and between relay and eNodeB or D2D user equipment, is defined.
The attainable data rate for user equipment in the first and second hops is expressed in
terms of SINR, transmit power, bandwidth, and thermal noise. The end-to-end data rate for
user equipment on a resource block is the minimum of the attainable data rates over two
hops, divided by two.
Resource Allocation:
Research is ongoing to propose optimal resource allocation algorithms for D2D
communication, addressing challenges in interference management and resource allocation
efficiency.
Ultra dense Networks:
Ultra dense networks in 5G are crucial for handling increased traffic demands. These
networks will be dense and dynamic, posing challenges like interference and mobility. To
address this, new network functionalities are needed. Current LTE interference mitigation
techniques are limited and 5G needs more flexible solutions. Smart devices will interact
more with each other and the environment, requiring user-independent algorithms based
on contextual information. Overall, future networks aim to provide optimal connectivity with
minimal interference and energy consumption, adapting to changing requirements.
MULTI RADIO ACCESS TECHNOLOGY ASSOCIATION
In 5G networks, the integration of various radio access technologies is crucial. Devices need
to support not only the new 5G standard but also 3G, 4G LTE, WiFi, and possibly direct
device-to-device communication across difserent bands. Defining standards and spectrum
allocation for these networks is complex. Optimal user association, considering factors like
signal-to-interference ratio, load balancing, and operational simplicity, is a major concern.
Various methods, including biasing towards small cells and adaptive tuning, have been
proposed to improve edge rates and network performance. Game theoretic approaches are
also being explored for radio access technology selection. Overall, there is significant scope
for modeling, exploring, and optimizing base station-user associations in 5G networks.
FULL DUPLEX RADIOS
Efsorts to develop full-duplex radios aim to allow simultaneous transmission and reception
on the same channel, challenging the traditional assumption of half-duplex operation in
wireless systems. Full duplex could halve spectrum demands, as a single channel could be
used for both uplink and downlink. However, achieving full duplex requires efsectively
canceling self-interference, which is crucial for maintaining signal quality and throughput.
A MILLIMETER WAVE SOLUTION FOR 5G CELLULAR NETWORK
Millimeter wave (mmWave) technology is a key component of 5G cellular networks, ofsering
increased bandwidth and data rates. However, its implementation comes with challenges.
o Path Loss: MmWave signals sufser from high free space path loss due to their short
wavelength. This loss increases with frequency, leading to reduced coverage area
compared to lower frequency bands like 4G LTE.
o Blocking: MmWave signals are highly susceptible to blockages by obstacles such as
buildings and trees. This can result in significant signal attenuation, especially in nonline-of-sight scenarios.
o Atmospheric Absorption: Absorption by atmospheric gases, particularly oxygen, can
further reduce the range of mmWave signals. Rain can also cause absorption,
impacting signal strength.
o Antenna Design: MmWave systems require complex antenna arrays to mitigate path
loss and achieve beamforming. These antennas need to be small and efficient, which
poses challenges in terms of design and integration.
o Transceiver Architectures: The use of mmWave frequencies requires new transceiver
architectures to handle the increased bandwidth and power consumption. Analogto-digital converters (ADCs) and digital-to-analog converters (DACs) need to operate
at higher frequencies, leading to higher power consumption.
o Link Acquisition: Establishing and maintaining links between users and base stations
in mmWave systems is challenging, especially in environments with high mobility.
Beamforming techniques are essential but require precise alignment between
transmitters and receivers.
o Spectrum Utilization: MmWave bands ofser wide bandwidths, but efficient spectrum
utilization is crucial. Dynamic spectrum sharing and management techniques are
needed to maximize the use of available spectrum.
o Interference: MmWave signals are sensitive to interference from other sources
operating in the same frequency band. Advanced interference mitigation techniques
are required to ensure reliable communication.
Addressing these challenges is critical for the successful deployment of mmWave technology
in 5G networks. Advances in antenna design, transceiver technology, and signal processing
are key areas of research to enable the full potential of mmWave for future wireless
communication.
CLOUD TECHNOLOGIES FOR FLEXIBLE 5G RADIO ACCESS NETWORKS
Mobile Cloud Computing:
 Integration of cloud computing with mobile devices, ofsering computing, storage,
services, and applications over the Internet.
 Reduces costs, decouples services from existing technology, and provides flexibility in
resource provisioning.
 Two common methods:
o Mobile devices acting as resource providers.
o Cloudlet concept, placing cloudlets in public areas for direct mobile device
connection, bypassing latency and bandwidth issues.
 Follows basic cloud computing concepts and must fulfill specific requirements such as
adaptability, scalability, availability, and self-awareness.
Radio Access Network as a Service (RANaaS):
o Centralizes radio access network functionalities based on service requirements,
ofsering flexibility and adaptability.
o Partly centralizes functionalities, improving data storage and processing capabilities.
o Functional split of radio protocol stacks between central RANaaS platform and local
radio access points increases degrees of freedom.
o Implementation requires characteristics similar to cloud computing platforms.
Joint Radio Access Network Backhaul Operation:
Connects small cells to RANaaS platform, requiring a refined transport network design for
data transmission.
Software-defined networking provides quicker reactions to failures and higher resource
utilization but increases computational efsorts.
Trends in 5G Technologies:
o Increase in machine-to-machine connections and data traffic.
o Necessitates improvements in quality-of-service management, such as spectral
efficiency and latency reduction.
CONCLUSION
The paper provides a detailed survey of 5G wireless cellular communication systems,
focusing on performance requirements and technologies. It covers capacity, data rate,
spectral efficiency, latency, energy efficiency, and quality of service. The architecture
includes massive MIMO, NFV, cloud computing, and device-to-device communication. Shortrange technologies like WiFi and millimeter wave communication are discussed, as are key
emerging technologies such as interference management and spectrum sharing. The paper
aims to inspire further research in next-generation networks.