Long Term Evolution (LTE)

Both radio and core nework evolution
all-IP packet-switched architecture
standardized by 3GPP
lower CAPEX ans OPEX involved

Evolved from Universal Mobile Telecommunication System (UMTS), which in turn evolved from the Global
Also 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.

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 can 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 duples FD
(MIMO) Multiple Input Multiple Output transmissions – LTE devices have to support this. 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

  1. User Equipment (UE)
  2. Evolved UMTS Terrestrial Radio Access Network (E-UTRAN).
  3. Evolved Packet Core (EPC).

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)

Ref:
3GPP on LTE – https://www.3gpp.org/technologies/keywords-acronyms/98-lte
ETSI on LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception – https://www.etsi.org/deliver/etsi_ts/136100_136199/136101/10.03.00_60/ts_136101v100300p.pdf

One response to “Long Term Evolution (LTE)

  1. Its a good read , but too short , Would ne nicer to see more simplified explanation and diagrams

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