From LTE to 5GMO655 - Gerência de Redes de

ComputadoresThiago Müller Albertin - 189739

Agenda1. Existing Cellular Network2. Requirements and Vision3. Architecture4. Physical Layer5. MAC Layer6. Applications7. Quality and Sustainability8. Conclusion

Existing Cellular Networks● Global mobile traffic growth (70% in 2014).● Mobile devices growth (26% of devices are responsible for 88% of traffic).● Growth in mobile multimedia traffic (more than half of traffic since 2012).

○ user-oriented multimedia applications (video conferencing, streaming, online gaming).

● Anual download expectation around 1 TB per user by 2020.● New applications: IoT, IoV, D2D, M2M, e-Health, FinTech, Augmented

Reality.● Evolution of mobile wireless communication through generations.

○ Increased rate and new features.○ Digital modulation, frequency reuse, MIMO, HARQ, WCDMA, OFDMA.

● Difficult task for 4G LTE.○ Rate=150 Mbps, 600 RCC-connected users per cell.

5G Requirements● Hyper-connectivity and new emerging applications.● Increased data rates, bandwidth, coverage and connectivity.● Reduced round trip latency and energy consumption.● 3GPP / 5G-PPP timeline: 2020● 8 major requirements:

1. 1~10 Gbps data rates in real networks.2. 1 ms round trip latency.3. High bandwidth in unit area.4. Enormous number of connected devices.5. Perceived availability of 99.999%.6. Almost 100% coverage for “anytime anywhere” connectivity.7. Reduction in energy usage by almost 90%.8. High battery life.

5G Vision and Contributions● Ericsson: networked society; affordable and sustainable.

○ Demonstration at 2018 winter Olympics.● Qualcomm: enabling innovative services; connecting industries and devices;

improved user experience.○ Development of 4G and 5G in parallel.

● Huawei: massive capacity and connectivity; diverse services, applications and users; network deployment scenarios.

○ Collaboration with international trade associations.● Docomo 5G: extensive and enriched content; everything connected wirelessly;

pervasive connectivity and real-time content delivery trends.○ Integration of both the higher and lower frequency bands.

● Nokia: heterogeneous deployment; augmented reality and tactile Internet; sufficiently accurate channel modes.

○ Optimization of spectrum usage.

5G Vision and Contributions● Samsung: IoT; enhance multimedia experience; extensive cloud computing.

○ Billions of autonomously connected diverse devices.● 5GPP and METIS: software-driven 5G; multi-tenancy; scalable and sustainable.

○ Early agreements with major stakeholders.● 5G Training: disruptive technology directions; architecture and key technologies;

personal mobile Internet and D2D.○ Coordination of workshops and conferences.

● 5G Forum: commercialization of 5G by 2020; interlaced heterogenous networks.○ Collaborative R&D efforts between South Korea, Japan and China.

● 5GNOW: abandon synchronism and orthogonality; unified frame structure concept; universal filtered multi-carrier.

○ Use of non-orthogonal asynchronous waveforms.

5G Architecture● From BS centric to device centric network.● From macro hexagonal to smaller cell.

○ macro, micro, pico and femto cells.

● From user as final resolution to user as participant.

● From omnidirectional antennas to sectorized and directional antennas.

● Decoupling of user plane and control plane.● Emerging technologies: SDN, Cloud-RAN and

HetNets.

5G Architecture - Radio Network Evolution● Move from BS centric towards device centric topology.● Use of higher frequencies (mm-waves) for communication.

○ Limited propagation and penetration.○ Site specific layout.○ Preference for LOS over NLOS communication.○ exploration of reflected, scattered and diffracted signals upon NLOS.

● Operability with a huge number of users, variety of devices and services.● Integration of 5G BSs with legacy cellular networks (4G, 3G and 2G).

○ Hybrid mm-wave (5G) and legacy (4G) systems.○ Mm-wave standalone systems.○ Mm-wave BS grids.

● Beamforming extends coverage, reduces interference and improves link quality.

5G Architecture - Radio Network Evolution

5G Architecture - Advanced Air Interface● Small wave demands small antenna sizes (allowing higher amount).● Array antennas control waves in the desired direction (cancelling on

others).● Change from omnidirectional to directional transmission.

○ Achieved through adaptive beamforming techniques and SDMA.

● Hardware constraints:○ High power consumption.○ Unavailability of high rate A/D and D/A converters on every antennas.

5G Architecture - Smart Antennas● Mitigate interference, maintain optimal coverage

and reduce transmission power.● Narrow beams transmit more energy at higher

frequency.● Same channel is used by different beams (less

co-channel interference).● Beamforming with fractional loading factor

further reduce co-channel interference.● Infrastructure expenses and complex operations

impede usage.

5G Architecture - Smart Antennas● Space, size and power are constraints on mobile devices.● Space is a constraint on BSs.● Antenna configurations:

○ Horn antennas at transmitter.○ Patch antennas at receiver.○ Array antennas in urban areas.

● Array configurations:○ Circular Array: better coverage.○ Planar Array: better directivity.○ Segmented Array: achieve a level of directivity and scan-range.

5G Architecture - SDN (Software Defined Network)● Changes emphasize on small cells and increased number of smart

antennas.● Configuration and maintenance of server and routers is a challenge.● SDN split between control and data planes (swiftness and flexibility).

○ C-plane via macro cell with low frequency, U-plane via serving cell with high frequency.○ Increase in U-plane is independent (high data at required locations).○ U-plane requires CoMP (multiple BSs).○ Software as manages the C-plane (less hardware constraints).

● SDN applied as SON (Self-Organized Network) solution.○ planning, configuration, management, optimization and healing of RAN.○ SON algorithms perform changes automatically.

5G Architecture - SDN (Software Defined Network)

5G Architecture - Cloud-RAN● Inter-cell interference, CAPEX and OPEX limit network capacity.● Based on fundamentals of centralization and virtualization.● Improve mobility, coverage and energy efficiency, and reduce costs.● BBU: process baseband signals.● RRH: process radio signals from an antenna.● BBU deployed with BSC, connected to RRH via fiber (fronthaul).● Baseband resources pooled at remote CO (not at the cell site).● BBUs centralized at a virtual BBU pool (multiplexing gains).

○ Simplified BSs and cloud computing handling the complex control.○ NFV: load balancer function.

5G Architecture - Cloud-RAN

5G Architecture - HetNets● Multi-RAT networks, with GSM, UMTS, LTE, Wi-Fi.● Coverage and fast moving x Capacity and stationary/slow moving.● Deployment of large number of small cells with overlaps (frequency

reuse).○ macro cell: 40 Km, 1000+ users.○ micro cell: 2 Km, 200 users.○ pico cell: 200 m, 100 users.○ femto cell: 50 m, 16 users.

● Require coordinated operation (interference reduction).○ Multi-tier networks and reverse TDD protocol.

■ Handle intra-tier and inter-tier channel estimation.■ BS and small cell AP downlink and uplink operate inversely.

5G Architecture - HetNets

5G Physical Layer - mm-Waves● Capacity depends on spectral efficiency, bandwidth and cell size.● Physical technologies at the boundary of Shannon capacity.● "Sweet Pot” or “Beachfront Spectrum" from 300 MHz to 3 GHz.

○ Reliable propagation (over distances or environments).

● Unused EHF mm-wave band from 3 to 300 GHz.○ US FCC opened the spectrum between 59 ~ 64 GHz and 81 ~ 86 GHz.○ Used by speed radars, airport communication and military applications.○ Small fraction can support hundred times more data rate and capacity.

5G Physical Layer - mm-Waves● Challenges:

○ Unavailability of standard channel model.○ Biological safety (non-ionizing and thermal characteristics).

● Channel characterized by propagation loss, signal penetration, doppler and multipath.

● Propagation Loss:○ LFSL = 32.4 + 20 log10f + 20 log10R // f = carrier frequency, R = transmitter-receiver distance○ Losses are prominent at higher frequencies.

● Shorter wavelengths enable dense packing of smaller antennas in a small area.

● mm-wave links are capable of casting very narrow beams.

5G Physical Layer - mm-Waves● Penetration and LOS communication:

○ Propagation in diverse environments (indoor and outdoor, through and around).○ Common build materials and structures present high penetration resistance.○ Movement of people generate shadowing effect.

● Multipath and NLOS communication:○ Relays at additional locations.○ Signal reception in more than one path.○ More multipath components are detected during rain.

● Doppler:○ Characterized by carrier frequency and mobility (apparent change in the frequency).○ Reduced by packet sizing, coding and reduced angular spread in narrow beam

transmissions.

5G Physical Layer - Adaptive Beamforming● Directional beams can be created, controlled, trained, steered and

measured.● Analog:

○ Coefficients applied to modified RF signal.○ simple and effective with less flexibility.

● Digital:○ coefficients are applied per RF chain, over modulated baseband signals.○ Better performance at increased complexity and cost.

● Hybrid:○ Provide sharp beams with phase shifters.○ At analog domain and flexibility of digital domain.

● Narrow beams for data and broader beams for control.

5G Physical Layer - Adaptive Beamforming● Antenna training protocols:

○ Communication only possible when the beams are aligned (not non-aligned or attenuated).

○ Discover the best beam direction pair.○ Narrowband pilot signals and multipath angular spreads determine pointing directions.○ Simultaneous steering of coded multiple beam angles, in a training packet.

● Angle of arrival:○ AOA distributions are generated for every transmitter, with Azimuth combinations for all

links plotted for receiver and transmitter.○ Transmitter at BS should point at the receiver direction, with a maximum beam steering

of 60º.○ Also useful for finding alternate paths for NLOS.

■ identified by ranking signal strengths of all training beam pairs.

5G Physical Layer - Sectorized Antennas● Switched beam systems use fixed antenna patterns from specific

directions.● Multiple antennas traverse a fixed arc-like sector.

○ High gain over a range of azimuths.○ Each range divided into overlapping sectors.

● Beam combining protocols and SDMA can be employed with FDMA/TDMA.

5G Physical Layer - Massive MIMO● BS with a huge number of antennas.● Grid of antennas is capable of directing horizontal beams (for Azimuth)

and vertical beams (for elevation).● Superposition of wavefronts.● Wavefronts add constructively phases at the intended location and

reduces their strength everywhere else.● Require algorithms for modulation and scheduling (channel estimation

and channel sharing).○ TDD preferred over FDD (avoid the complexity with channel estimation and channel

sharing).○ CSI (Channel State Information) induces a huge amount of information exchange

overhead.

5G Physical Layer - Massive MIMO

5G Technologies- Beamforming Explained.mp4

mmWave massive MIMO for wireless and broadband.mp4

5G Physical Layer - Full Duplex Radio● FD in the same frequency simultaneously.

○ double the spectral efficiency of a point-to-point radio link.

● Crosstalk, path loss, fading and internal interference impede the FD.● Achieved with beamforming, massive MIMO and small cells.● SI (Self Interference) cancellation:

○ Passive: exploits directional antennas, absorptive shielding and cross-polarization.○ Active: uses information of node's transmit signal to cancel the interference.○ Approach: two transmit antennas, d and d+λ/2 distant, to the receive antenna.

5G MAC Layer - SDMA (Spatial Division Multiple Access)

● Separate users on shared frequency by isolating them with directional beams.

● Natural fit for adaptive antennas, beamforming and device centric architecture.

● Reduced interference and increased frequence reuse.

● Require beamforming coefficients to be trained and BSs to simultaneously transmit and receive multiple beams in different directions.

5G MAC Layer - Directional MAC Protocols● MAC layer protocols must exploit spatial features.

○ CTA (Channel Time Allocation): TDMA with time partitioned in super frames (many timeslots).

○ DMAC (Directional MAC): upper layer is assumed to be aware of its neighbors.○ DNAV (Directional Network Allocation Vector): Integrant of DMAC), with table track

directions where the node must (or must not) initiate a transmission.○ MMAC (Multihop MAC): outperforms DMAC by integrating DO (Direction-Omni) and DD

(Direction-Direction) neighbor identifying techniques.○ STR (Simultaneous Transmission and Reception)○ RTS/CTS (Request/Clear to Send): RTS/CTS packets transmitted on every beam in the

same direction, for both omni and directional modes.○ DCSMA/CA (Directional Carrier Sense Multiple Access with Collision Avoidance): based on

Markov Chain model of multi user SDMA.

5G MAC Layer - Advanced Multiple Access Techniques

● Huge mm-wave spectrum enables carrier aggregation (increased bandwidth).

○ Mm-wave channels: wide bandwidth, small delay spread, short cyclic prefix, wide subcarrier spacing.

● OFDMA (Orthogonal Frequency Division Multiple Access):○ Divides a channels into multiple narrow orthogonal bands, spaced for interference

avoidance.○ Each band is divided into thousands of sub-carriers, assigned to users as needed.○ Synchronization and orthogonality are challenges.

● IDMA (Interleave Division Multiple Access).● GFDM (Generalized Frequency-Division Multiplexing).● FBMC (Filter Bank Multi-Carrier).

5G Applications● Motivation behind the commercial release of 5G.● Solutions for a wide range of public and private sectors.● Enormous number of connections and diverse nature of devices.● Not originally supported by 4G (native support from 5G).

5G Applications - D2D Communication● Direct communication between nearby devices

(device centric nature).● Communication scenarios:

○ Relaying○ Coverage holes○ Cellular offloading○ Content distribution○ Gaming

● Low latency, energy efficiency and scalability.● Challenges: spectrum sharing, interference

and multi-hop communications.

5G Applications - M2M Communication● Automated data generation, processing, transfer

and exchange between intelligent machines.● Areas:

○ Home and industry automation○ Road and traffic management○ Infrastructure management○ Healthcare○ Metering

● High number of devices, small data, sporadic transmissions, high reliability, low latency, wide coverage area.

● Network uncertainty and mobility lead to interference.

5G Applications - IoT (Internet of Things)● Millions of connections and interoperability for numerous smart objects.● Ubiquitous connectivity of autonomously communicating IoT-enabled

devices.● Requires high bandwidth, cooperation among massive, distributed,

autonomous and heterogeneous components.● Internet from human centric to M2M platform.● Challenges: automated sensor configuration, context discovery,

acquisition, modeling and reasoning, selection of sensors in “sensing-as-a-service” model, security-privacy-trust, context sharing.

5G Applications - IoT (Internet of Things)

5G Applications - IoV (Internet of Vehicles)● Network of interconnected vehicles (robust traffic management and

reduced collision probabilities).● Huge spatio temporal data, high safety and security.● Requires high bandwidth, pervasive availability, and low latency.● Explore roadside relay nodes.● Challenge: provide a reliable high data rate on high speed trains.

5G Applications - Healthcare and Wearables● Advancements in sensing and communication technologies.● Ageing world in less than 30 years.● Devices capable of measuring multiple physiological signals.

○ BAN (Body Area Network)● Understanding diseases’ pathophysiology.● Requirements: huge data processing, storage and real time

communications.● Constraint: bandwidth limitation.

5G Applications - Miscellaneous● Financial industry.

○ Banking, payments, personal finance management, social payments, peer to peer transaction and local commerce.

● Smart Grids.○ Data collection, power line monitoring, protection and demand/response management.

● Smart Homes.● Smart Cities.

5G Quality Expectations● 1 ms round trip delay, perceived 99.999% availability and 100% coverage.● QoS (Quality of Service):

○ Metrics like bandwidth, error rate, signal strength, along with traditional RTT delay.○ Guaranteed by abundant mm-wave spectrum and deployment of beamforming

antennas.

● QoE (Quality of Experience):○ Perceived end to end quality/satisfaction (high QoS does not mean high QoE).○ Interactiveness, feeling of the product, ability to serve purposes, fitting into the entire

context.

● SON (Self-Organized Network):○ Offer autonomic functionalities of self-configuration, self-optimization and self-healing.○ Improved user experience and network automation by reducing human intervention.

5G Sustainability● ICT impact global energy consumption (backbone: 12% 2010, 20% by

2020).● Energy Aware BS:

○ Substantial portion of energy consumption in wireless networks.○ Sleep-mode, traffic variation deployment scheme, cell zooming, renewable energy

sources.

● Energy-Efficient Backhaul:○ Cognitive backhaul deployment schemes.○ Backhaul multiplexing power.

● Energy and Cost Effective Network:○ CF (Consumption Factor).

● C-RAN to Reduce Overheads and Energy Drains:○ Simplified cell sites (processing shifted to Cloud Data Center).

Conclusion● Increase in data (multimedia) usage and proliferation of smart devices.● Increase in data rate, connectivity and QoS.● New architectural paradigm (air interface, smart antennas, HetNets,

C-RAN).● New underlying physical layer technology (mm-wave channel, LOS/NLOS,

beamforming, massive MIMO).● Adaptations on MAC layer protocols and multiplexing schemes (SDMA).● New emerging applications (D2D, M2M, IoT, IoV, Healthcare).● New QoS, QoE and SON features.● Green and sustainable technology.

Conclusion

QuestionDescribe five 5G open issues/challenges that require research works.

Article: M. Agiwal, A. Roy and N. Saxena, “Next Generation 5G Wireless Networks: A Comprehensive Survey” IEEE Communications Surveys & Tutorials, vol. 18, iss. 3, pp. 1617–1655, Feb 2016.

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IEEE Communications Surveys & Tutorials, vol. 18, iss. 3, pp. 1617–1655, Feb 2016.● T. S. Rappaport et al., “Millimeter wave mobile communications for 5G cellular: It will work!” IEEE

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toward 5G wireless networks” IEEE Commun. Mag., vol. 53, no. 6, pp. 59–65, Jun. 2015.● “5G Technologies- Beamforming Explained.mp4”. Disponível em:

<https://www.youtube.com/watch?v=OidnBOcXvic>. Acesso em 09 de Nov. 2017.● “mmWave massive MIMO for wireless and broadband”. Disponível em:

<https://www.youtube.com/watch?v=38kp5uRrG2s>. Acesso em 09 de Nov. 2017.