5G

In the course of evolution of RAN ( Radio Access layer) technologies 5G outsmarts 4G-2010 which comes in succession after 3G-2000 , 2.5G, 2G -1990 and 1G / PSTN -1980 respectively . Among the mosy striking features of 5G –

  • entirely IP based
  • ability to connect 100x more devices ( IOT favourable )
  • speed upto 10 Gbit/s
  • high peak bit rate
  • high data volume per unit area
  • virtually 0 latency hence high response time

Thus it can accomodate the rapid growth of rich mulimedia application like OTT streaming of HD content, gaming , Augmented reality so on while enabling devices connected to Internet of Things sto onboard the telecommunication backbone with high system spectral efficiency and ubiquitious connectivity .

Infact 5G has seen maximum investment in year 2020 in revamping infrastrcuture as compared to other technologies such as IoT or even Cloud. This could be partly due to high rise in high speed communication for streaming and remote communication owining to steep rise in remote learning adn working from home scenarious.

img source statista – global-telecom-industry-priority-investment-areas

Spectrum

5G is specified to operate over range 1 GHz to 100 GHz.

  • Low-band spectrum (below 2.5 GHz) provides excellent coverage,
  • mid- band spectrum (2.5–10 GHz) provides a combination of good coverage and very high bitrates,
  • high band-spectrum (10–100 GHz) provides the bandwidths needed for the highest bitrates (up to 20 Gb/s) and lowest latencies

Workplan for 5G standardisation and release

The Workplan started in 2014 and is ongoing as of now (2018)

image source : 3GPP “Getting ready for 5G”

3GPP is the standard defining body for telecom and has specified almost all RAN technologies like GSM , GPRS , W-CDMA , UMTS , EDGE , HSPAand LTE before .

Applications of 5G

5G targets three main use case

  • enhanced mobile broadband (eMBB),
  • massive machine type communications (mMTC)
  • ultra-reliable low latency communications (URLLC) (also called critical machine type communications (cMTC))
sources : whitepaper ericsson

Long Term Evolution (LTE), VOLTE and VOWifi

LTE stands for Long Term Evolution and is a registered trademark owned by ETSI (European Telecommunications Standards Institute) for the wireless data communications technology and a development of the GSM/UMTS standards.

  • Both radio and core network evolution
  • All-IP packet-switched architecture
  • standardised by 3GPP
  • lower CAPEX ans OPEX involved

LTE evolved from an earlier 3GPP system known as the Universal Mobile Telecommunication System (UMTS), which in turn evolved from the Global System for Mobile Communications (GSM). Also it is aligned with 4G (fourth-generation mobile)

LTE is backward compatible with GSM/EDGE/UMTS/CDMA/WCDMA systems on existing 2G and 3G spectrum , even hand-over and roaming to existing mobile networks.

Motivation for evolution

Wireless/cellular technology standards are constantly evolving for better efficiency and performance.LTE evolved as a result of rapid increase of mobile data usage. Applications such as voice over IP (VOIP), streaming multimedia, videoconferencing , cellular modemetc.

It provides packet-switched traffic with seamless mobility and higher qos than predecessors. Also high data rate, throughput, low latency and packet optimized radioaccess technology on flexible bandwidth deployments.

Timeline of Evolution 

  • GSM  : calls  on circuit switching ( CS ) between 2 parties for communication. Dedicated circuits are used for voice and SMS.
  • GPRS : packet switching (PS) is introduced for data services
  • UMTS / 3G : network elements begin evolving into PS . No changes to core.
  • EPC / LTE/VOLTE : No circuit switched domain at all .

Performance

Peak Data Rate
uplink – 75Mbps(20MHz bandwidth)
downlink – 150 Mbps(UE Category 4, 2×2 MIMO, 20MHz bandwidth) , 300 Mbps(UE category 5, 4×4 MIMO, 20MHz bandwidth)

carrier bandwidth

range from 1.4 MHz up to 20 MHz. Ultimately bandwidth used by carrier depends on frequency band and the amount of spectrum available with a network operator

Mobility 350 km/h

Multiple Access Schemes
uplink: SC-FDMA (Single Carrier Frequency Division Multiple Access) 50Mbps+ (20MHz spectrum)
downlink: OFDM (Orthogonal Frequency Division Multiple Access) 100Mbps+ (20MHz spectrum)

Multi-Antenna Technology , Multi-user collaborative MIMO for Uplink and TxAA, spatial multiplexing, CDD ,max 4×4 array for downlink

Coverage

5 – 100km with slight degradation after 30km

LTE architecture supports hard QoS and guaranteed bit rate (GBR) for radio bearers.

Technology

All interfaces between network nodes are IP based
Duplexing – Time Division Duplex (TDD) , Frequency Division Duplex (FDD) and half duplex FD

MIMO ( Multiple Input Multiple Output ) transmissions –

Allows the base station to transmit several data streams over the same carrier simultaneously.
Modulation Schemes

QPSK, 16QAM, 64QAM(optional)

LTE Architecture

Primarily composed of

User Equipment (UE)

  • Mobile Termination (MT)
  • Terminal Equipment (TE) 
  • Universal Integrated Circuit Card (UICC) : also known as the SIM card for LTE equipments. It runs an application known as the Universal Subscriber Identity Module (USIM).

2. Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)

handles the radio communications between the mobile and the evolved packet core. High level representation for  eNodeB or eNB

role of eNB :

sends and receives radio transmissions to all the mobiles using the analogue and digital signal processing functions of the LTE air interface.

eNB also controls the low-level operation of all its mobiles, by sending them signalling messages such as handover commands.

3. Evolved Packet Core (EPC)

This sub system resembles IMS environment.

Packet Data Network (PDN) Gateway (P-GW) communicates with the outside world simillar to GGSN ( GPRS support node ) and SGSN ( serving GPRS support node ) in UMTS and GSM.

Home Subscriber Server (HSS) is a central database that contains information about all the network operator’s subscribers. Almost simillar to HLR/AAA in 2G /3G architcture.

Mobility management entity (MME) controls the high-level operation

For a roming user in Visited-PLMN , he is connected with the E-UTRAN, MME and S-GW of the visited LTE network. However, LTE/SAE allows the P-GW of either the visited or the home network to be used, as shown in below:

For roaming prepaid charging , accounting flows are made to access prepaid customer data, via P-Gateways or CSCF in an IMS environment.

LTE-Advanced

LTE devices capable of CAT6 speeds (Category 6 )
Increased peak data rate – downlink 3 Gbps, Uplink 1.5 Gbps ( 1 Gbps = 1000 Mbps)
Spectral efficiency from 16bps/Hz in R8 to 30 bps/Hz in R10
Carrier Aggregation (CA)
Enhanced use of multi-antenna techniques
Support for Relay Nodes (RN)

References :

MIMO ( multiple-input and multiple-output )

SISO – Single Input Single Output
SIMO – Single Input Multiple output
MISO – Multiple Input Single Output
MIMO – Multiple Input multiple Output

Multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation.
Key technology for achieving a vast increase of wireless communication capacity over a finite electromagnetic spectrum.

Antenna configuration – implies antenna spatial diversity by useing arrays of multiple antennas on one or both ends of a wireless communication link
boost channel capacity.
combats multipath fading
enhance signal to noise ratio,
create multiple communication paths

Applies to wifi
IEEE 802.11n (Wi-Fi), IEEE 802.11ac (Wi-Fi)
as well as cellular networks
HSPA+ (3G)
WiMAX (4G)
Long Term Evolution (4G LTE)
power-line communication for 3-wire installations as part of ITU G.hn standard and HomePlug AV2 specification

Large capacity increases over given bandwidth and S/N resources
Greater throughputs on bands below 6 GHz,

multi-user MU-MIMO

simultaneous independent data links to multiple users over a common time-frequency resource

massive MIMO

enable the expansion of the useful spectrum to microwave and millimeter wave bands within the framework of 5G cellular communication.

microdiversity MIMO

MIMO modes (60m)

Diversity – Alamouti algorithm
Beam forming – create and aim the antenna pattern electronically
Spatial multiplex – use of precoding and shaping to unravel the multipath signals

challenges faced by mobile equipment vendors implementing MIMO in small portable devices.

Functions

3main categories: precoding, spatial multiplexing (SM), and diversity coding.

Precoding

multi-stream beamforming ( signal is emitted from each of the transmit antennas with appropriate phase and gain weighting such that the signal power is maximized at the receiver input ) , increases reception and reduce multipath fading

In line-of-sight propagation, beamforming results in a well-defined directional pattern. However, conventional beams are not a good analogy in cellular networks, which are mainly characterized by multipath propagation. When the receiver has multiple antennas, the transmit beamforming cannot simultaneously maximize the signal level at all of the receive antennas, and precoding with multiple streams is often beneficial. Note that precoding requires knowledge of channel state information (CSI) at the transmitter and the receiver.

Spatial multiplexing

High-rate signal is split into multiple lower-rate streams and each stream is transmitted from a different transmit antenna in the same frequency channel. If these signals arrive at the receiver antenna array with sufficiently different spatial signatures and the receiver has accurate CSI, it can separate these streams into (almost) parallel channels.

increasing channel capacity at higher signal-to-noise ratios (SNR).

Diversity coding

when there is no channel knowledge at the transmitter , a single stream is transmitted. The signal is emitted from each of the transmit antennas with full or near orthogonal coding. Diversity coding exploits the independent fading in the multiple antenna links to enhance signal diversity.

Ref :
https://www.comsoc.org
https://en.wikipedia.org/wiki/MIMO