Long Term Evolution (LTE) and 5th Generation Mobile Networks (5G)
Long Term Evolution (LTE)
What is LTE? LTE is the next generation of Mobile broadband technology Data Rates up to 100Mbps Next level of UMTS 3G technology Packet switched 3
Advantages Provides low latency Higher network throughput Increased data tranfer speed More cost effectiveness Improvement over 3G networks 4
Technical Architecture What is an LTE Network made of? LTE technologies LTE architecture LTE network elements 5
LTE Technologies Downlink: OFDM (Orthogonal Frequency Division Multiplexing) Uplink: SC-FDMA (Single Carrier Frequency Division Multiple Access) MIMO (Multiple Input Multiple Output) SAE (System Architecture Evolution) 6
MIMO Utilises the multipath signal propagation, present in all terrestrial communications Different diversity modes to make radiocommunications more robust Time diversity Frequency diversity Spatial diversity Improve data rates Spatial multiplexing 7
MIMO - Spatial Diversity Rx Diversity Different transmission paths, receiver sees two faded signals Increase Signal to Noise Ratio Tx Diversity Same data is transmitted redundantly over two antennas Signal copy is transmitted at different time More interference to other users Space time block codes Explained thoroughly at spatial multiplexing 8
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MIMO - Spatial Multiplexing Divide data into seperate streams Streams are transmitted independently via separate antennas To recover transimitted data stream, high amount of signal processing is needed Receiver uses a matrix to differentiate between the different data streams ri is the received signal in antenna i hij is the transmitted signal from antenna i received from antenna j 10
Spatial Multiplexing 11
MIMO - Beamforming Create a certain required antenna directive pattern Smart antennas are normally used can be controlled automatically according the required performance Combine elements in an antenna array to experience, at particular angles, constructive interference & destructive interference Change directionality by controlling phase and amplitude (beamforming) Phase array* systems predifined patterns switched according to required directionality Adaptive array streams infinite number of patterns, adjusted real-time * Array: More than one antenna lined up 12
Beamforming Send a pulse at different times (phase) Send last the pulse closer to the receiver, first pulse furthest from the receiver Last pulse smallest amplitude First pulse biggest amplitude With amplitude we control the constructive/destructive interference Changing amplitude is not mandatory Phase array beamforming 13
Beamforming θ is the angle we want to get d is the distance between antennas Δφ is the phase difference between components λ is wavelength Δφ = 360 * d * sin(θ) / λ 14
Beamforming To change the directionality we must know where the receiver is We receive a signal to the array We calculate direction of arrival from the different phase in each antenna in the received signal Phase array has pairs of Δφ and θ (patterns) Adaptive array systems can beamform to any direction bigger cost & complexity 15
Beamforming (Switched vs. Adaptive array) Switched beamformer Adaptive beamformer 16
LTE Technologies Adaptive Modulation and Coding Downlink modulations: QPSK, 16-QAM, 64-QAM Uplink modulations: QPSK and 16-QAM Turbo Code Adaptive Spectrum The carrier could be 1.25MHz, 1.6MHz, 2.5MHz, 5MHz, 10MHz, 15MHz, 20MHz 17
LTE Network Elements Evolved Node B (enb) Connects user devices & telephone network Supports air interface Provides Radio resource managment functions Serving Gateway (SGW) Provides Mobility Responsible for Routing and Forwarding 18
LTE Network Elements Packet Data Network Gateway (PDN GW) Provides connectivity to Internet Provides QoS and mobility between 3G and non 3G networks Mobility Managment Entity (MME) Manages Mobility and provides security Operates in control plane and provides authentication User Equipment (UE) Users end device e.g cell phone 19
LTE Architecture 20
LTE Advanced - Outline 4G standard Carrier Aggregation MIMO Relay Nodes CoMP 21
ITU 4G Standards Based on an all-ip packet switched network. Peak data rates of up to 100 Mbit/s for high mobility Peak data rates of up to 1 Gbit/s for low mobility Support more simultaneous users per cell Scalable channel bandwidths of 5 20 MHz, optionally up to 40 MHz Peak link spectral efficiency 15-bit/s/Hz downlink, 6.75-bit/s/Hz uplink System spectral efficiency 3-bit/s/Hz/cell downlink, 2.25-bit/s/Hz/cell uplink (indoors) Smooth handovers across heterogeneous networks 22
Carrier Aggregation Increases capacity by increasing bandwidth Backward compatible with previous versions of LTE Uses more than one carrier at once to increase bandwidth Each carrier corresponds to a different channel in LTE band Each carrier in carrier aggregation is called component carrier The sum of carriers is called aggregated number of component carriers Component carrier bandwidth 1.4, 3, 5, 10, 15 or 20 MHz Maximum 5 component carriers aggregated Aggregated number of component carriers can be different for downlink & uplink Uplink component carriers <= Downlink component carriers Bandwidth of each component carrier can vary for downlink & uplink 23
Carrier Aggregation: Intra-band, Inter-band Component carriers use same band ( Intra-band ) Contiguous or Non-contiguous Contiguous: Each component carrier is adjacent to one another Simple, one transceiver is needed Signals are treated as one Non-contiguous: Component carriers do not need to be adjacent More complex, need for more transceivers Signals cannot be treated as one Component carriers use different bands ( Inter-band ) Non-contiguous Multiple transceivers are needed Impacts cost, performance & power 24
Carrier Aggregation 25
Relay Nodes Two types Type 1: Appears as extra enodeb Type 2: Appears as the main enodeb of the cell Connect to an existing enodeb to relay signals Called Donor enodeb Does not work like a reapeater Retransimtts the actual signal Low power base stations 26
Relay Nodes Fix reduced data rates at the cell edge Cell: area a wireless network is distributed Cell edge: furthest points in a cell Interference from other base stations Provide enhanced coverage and capacity at cell edges Relay closer to cell edge Increase network density More stations can support more user s equipment Network coverage extension Number of scenarios where LTE relay will be advantageous 27
Relay Nodes 28
Relay Nodes Usages 29
Coordinated Multi Point operation (CoMP) Coordination & Multipoint Coordination between multiple geographically seperated enodeb Improve network performance at cell edges Makes better utilisation of network Pass data from least loaded base stations Provides enhanced reception performance Multiple site reception increases received power Interference reduction Specialized coordination techniques, achieve constructive interference between cells 30
Coordinated Multi Point operation (CoMP) Two major types Joint processing: Base stasions simultaneously transmitting/receiving to/from user equipments Receiver data are combined for improved quality Coordinated scheduling or beamforming: Base stasions transmitting/receiving to/from user equipments in a coordinated manner Different signal transmissions in time from each base station 31
Coordinated Multi Point operation (CoMP) Transimission same time 32
Coordinated Multi Point operation (CoMP) Transmission at different time 33
5th Generation Mobile Networks (5G) 34
5th Generation mobile networks - 5G The next proposed telecommunications standard Aims at higher capacity than current 4G Higher density of mobile broadband users Support more reliable and massive machine communications Lower latency & lower battery consumption, for better implementation of the Internet of things. There is currently no standard for 5G deployments 35
5G Draft Standard The minimum requirements for downlink peak data rate is 20Gbit/s The minimum requirements for uplink peak data rate is 10Gbit/s Target downlink (user experienced data rate) is 100Mbit/s Target uplink (user experienced data rate) is 50Mbit/s Downlink peak spectral efficiency is 30bit/s/Hz Uplink peak spectral efficiency is 15bit/s/Hz Minimum requirement for connection density is 1,000,000 devices per km2. Requirement for bandwidth is at least 100MHz Bandwidths up to 1GHz are required for higher frequencies (above 6GHz) https://www.itu.int/md/r15-sg05-c-0040/en 36
Suggestions for 5G LTE Advanced Pro Backwards compatible improvments for LTE Advanced Up to 3Gbps data speeds & 640MHz carrier bandwidth Voice over LTE Packet switched No need for legacy circuit switched networks e.g. 2G, 3G enb-iot Simplification of enodeb to reduce cost & power consumption Machine to machine communications 5G New Radio (5G NR) Latency < 1ms Operations on unlicensed spectrums 37
5G New Radio Will deliver new levels of capability and efficiency Fiber-like speeds Multi-Gbps peak rates for both download and upload Uniform experience Reliable performance in challenging environments or at the cell edge Lower Latency As low as 1ms for interactive content, reduced buffering requirements and lag 38
Radio Access New Radio, Long Term Evolution integral parts of 5G radio access LTE expected to operate below 6 GHz frequencies New Radio envisioned to operate from sub-1 GHz up to 100 GHz Tight integration will enable aggregation of New Radio & LTE traffic Same core architecture for New Radio & LTE New Radio also operate to LTE bands Waveforms is a core technology component Many waveform proposals, most multi-carrier waveforms CP-OFDM was chosen, as in LTE (by 3gpp) 39
Channel Coding LDPC codes High efficiency Significant gains over turbo codes particularly for large block sizes suitable for mobile broadband Low complexity Easily parallelizable decoder scales to achieve high throughput at low complexity Low latency Efficient encoding/decoding enables shorter transmission time interval (TTI) 40
Massive MIMO Most compelling sub-6 GHz physical-layer technology for future wireless access Large antenna arrays at base stations to simultaneously serve many autonomous terminals Excellent spectral efficiency spatial multiplexing of many terminals in the same time-frequency resource Superior energy efficiency by virtue of the array gain, that permits a reduction of radiated power Decoding at the receiver could be energy hungry Complex issue 41
The more antennas, the... 42
The more antennas, the... 43
The more antennas, the... 44
The more antennas, the... 45
mmwave 30GHz - 300GHz Wavelength from 1cm to 1mm (milimiter wave) λ = c/f High atmospheric attenuation Propagation only to line-of-sight Numerous wireless challenges Path loss Blockage from hand, body, foliage Increased RF front end complexity Circuitry between antenna and mixer 46
Qualcom Research on mmwaves Utilise adaptive beamforming Increase coverage Minimize interference Expirement on channel response Alternate paths can have a very high receive signal Overcome hand blocking Home measurements penetration of walls path loss when walls obstruct line of sight 47
Reflected signal has higher voltage than original. We can exploit that 48
Hand blocking Shadowing occurs from user s hand Use multiple antennas to beamform around users hand Greater RF front end complexity Qualcom measured gain of the approach for all direction 49
Hand blocking 50
Wall penetration Shadowing from walls when indoors We measure the path loss from wall shadowing Better estimate nodes needed for indoors communications Results can vary based on construction materials Qualcom measurements for frequencies from 22 to 43GHz For one or two walls 51
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