Wireless data transfer – GSM

Applied Wireless Electronics
Grzegorz Budzyń
Lecture 7:
Wireless data transfer – GSM
Plan
• WiFi - supplement
• GSM 2.5G+ standards
– HSCSD
– GPRS
– EDGE
– UMTS
– HSDPA
– HSUPA
– LTE
WiFi - Supplement
WiFi – new standards
• The old standards cover 80-90 % of the
bandwidth demand of today’s mobile
applications
• New standards enter the market:
– 802.11ac
– 802.11ad
WiFi – 802.11ac
• Major features:
– Wider channels:
• Higher data rates – up to 1.3Gbps per radio
• 802.11ac mandates support of 80MHz wide
channels with optional 160MHz wide channels to
achieve higher data rates than are achieved with
802.11n
WiFi – 802.11ac
• Major features:
– Wider channels:
• Main disadvantage – smaller number of available
channels
WiFi – 802.11ac
• Major features:
– Higher encoding density:
• Higher bit density per packet
• 256-QAM modulation used
– Increased number of spatial streams:
• Higher data rates per AP/client link
• Up to eight spatial streams, further increasing the
data rate for each radio
WiFi – 802.11ac
• Major features:
– Beamforming:
• Greater wireless AP/client link reliability
– Multi-user MIMO
• Greater AP/client capacity and efficient use of spectrum
• Supports simultaneous transmissions to multiple clients
and maximizes RF band utilization
• Up to four distinct clients can receive data
simultaneously from a single AP at full channel data rate
WiFi – 802.11ac
• Timetable for commercial availability
WiFi – 802.11ad
• IEEE 802.11ad is an amendment to the
802.11 WLAN standard which enables up to
7 Gbps data rates in the unlicensed and
globally available 60 GHz band
• The 60 GHz band has wider channels,
enabling higher data rates over short
distances (1m – 10m)
WiFi – 802.11ad
• Main applications:
– Removing wires between High-Definition
multimedia, computer displays, I/O and
peripheral,
– peer to peer data synchronization
– higher speed LAN
WiFi – 802.11ad
• A shared MAC layer with existing 802.11
networks enables session switching between
802.11 networks operating in the 2.4 GHz, 5
GHz and 60 GHz bands
• The 802.11ad MAC layer has been extended:
– to include beamforming support
– address the 60 GHz specific aspects of channel
access, synchronization, association, and
authentication
GSM - Introduction
Cellular Network
• Base stations transmit to and receive from mobiles at the
assigned spectrum
– Multiple base stations use the same spectrum (spectral reuse)
• The service area of each base station is called a cell
• Each mobile terminal is typically served by the ‘closest’ base
stations
– Handoff when terminals move
Cellular Network Generations
• It is useful to think of cellular Network/telephony in
terms of generations:
–
–
–
–
0G: Briefcase-size mobile radio telephones
1G: Analog cellular telephony
2G: Digital cellular telephony
3G: High-speed digital cellular telephony (including video
telephony)
– 4G: IP-based “anytime, anywhere” voice, data, and
multimedia telephony at faster data rates than 3G
(to be deployed in 2012–2015)
GSM Services
• Voice, 3.1 kHz
• Short Message Service (SMS)
– 1985 GSM standard that allows messages of at most 160 chars. (incl.
spaces) to be sent between handsets and other stations
– Over 2.4 billion people use it; multi-billion $ industry
• General Packet Radio Service (GPRS)
– GSM upgrade that provides IP-based packet data transmission up to
114 kbps
– Users can “simultaneously” make calls and send data
– GPRS provides “always on” Internet access and the Multimedia
Messaging Service (MMS) whereby users can send rich text, audio,
video messages to each other
– Performance degrades as number of users increase
– GPRS is an example of 2.5G telephony – 2G service similar to 3G
Data transfer in GSM
• The "data over cellular" bearer services are part of the
Phase 2 implementation of GSM
• The basic data transfer technology is called CSD
(Circuit Switched Data)
• A GSM network’s data transfer facility allows the
digital equivalent of modem transmissions - known as
data streaming - at data speeds of up to 9,600 bits per
second in GSM900 and 14,400 bits per second in
GSM1800 networks
GSM – frequency slots
GSM Frequencies
• Originally designed on 900MHz range, now also
available on 800MHz, 1800MHz and 1900 MHz
ranges.
• Separate Uplink and Downlink frequencies
– One example channel on the 1800 MHz frequency band,
where RF carriers are space every 200 MHz
UPLINK FREQUENCIES
1710 MHz
DOWNLINK FREQUENCIES
1785 MHz
1805 MHz
UPLINK AND DOWNLINK FREQUENCY SEPARATED BY 95MHZ
1880 MHz
Data bursts – Normal burst
• Modulation used in GSM is GMSK -> 270kb/s
GSM Architecture
Data transfer in GSM
Data transfer in GSM
Mobile telephony generation
Data transfer standard
2G
CSD
2.5G
HSCSD
GPRS
EDGE
3G
UMTS
Data transfer in GSM
Mobile telephony generation
Data transfer standard
3.5G
HSDPA
HSUPA
HSPA+
LTE
4G
LTE Advanced
WiMAX
GSM 2.5G+ standards
HSCSD
• High-speed circuit-switched data (HSCSD), is
an enhancement to circuit switched data
(CSD), with data rates up to 57.6 kbit/s
• Channel allocation is done in circuit-switched
mode, as with CSD
• Higher speeds are achieved as a result of
superior coding methods, and the ability to
use multiple time slots to increase data
throughput (up to 4 slots)
HSCSD
• Pro:
– Flexible bearer service (BS) for higher data rates
up to 57.6kb/s (1800MHz) or 38.4kb/s (900MHz)
– Transparent and non-transparent bearer
services
– Rate adaptation for several standard interfaces
incl. X.30/V.110, V.24, etc.
HSCSD
• Cons
– Circuit-switched access, which is often
inefficient for data services that are bursty in
nature
– Higher call blocking probability due to multi-slot
allocation
– Possible high cost of service as it competes with
voice service for the same resources
GPRS
GPRS
• General packet radio service (GPRS) is a
packet oriented mobile data service
• It is available both in 2G and 3G networks
• In 2G systems, GPRS provides data rates of
56-114 kbit/second
• Allows for efficient use of the bandwidth
(statistical multiplexing)
• Circuit switching & Packet switching can be
used in parallel
Source: [1]
GPRS – statistical multiplexing
GPRS - Features
•
•
•
•
Constant connectivity
GPRS is an overlay network over GSM
Billing based on volume of data transferred
GPRS uses radio channel 200kHz wide carring
271kbps of data
• This is divided into 8 slots 34kbps each (14.4
kbps after corrections)
• 8*14.4 = 114kbps
GPRS - Coding
• GMSK and channel encoding based on a
convolutional code used
• Four coding schemes:
– CS-1 – speed: 8.0 kb/s per slot
– CS-2 – speed: 12.0 kb/s per slot
– CS-3 – speed: 14.4 kb/s per slot
– CS-4 – speed: 20.0 kb/s per slot
GPRS Terminals
• Class A:
– MS supports simultaneous operation of GPRS
and GSM services
• Class B:
– MS able to register to both services but works
only in a chosen one
• Class C:
– MS works either in GPRS or in GSM mode
EDGE
EDGE
• Enhanced Data rates for GSM Evolution
(EDGE) is further improvement of data
transmission in GSM networks
• Packet switched technology
• Main difference comparing to GPRS is the
change of modulation technology: from
GMSK to 8PSK
• Performance sensitive to radio conditions
Influence of EDGE on the GSM
network structure
Source: [3]
EDGE - modulation
Source: [3]
EDGE - performance
UMTS
UMTS
• UMTS - Universal Mobile
Telecommunications System is part of 3G
and 4G systems
• Unlike previously described techniques
UMTS requires new base stations and new
frequency allocations
• UMTS network is very similar to GSM
• The most common form of UMTS uses WCDMA but also TD-CDMA and TD-SCDMA
UMTS – Network architecture
• RNC – Radio Network Controller
UMTS modes
• UMTS works in two modes – UMTS–FDD or
UMTS-TDD
• In both modes there are used:
– CDMA
– QPSK modulation
– Multiple channel coding and bearer rates
– Asynchronous operation
• Data rate up to 2 Mbps
UMTS - Features
• Full packet driven architecture
– For voice and data transmission
– Packet based networks allow for an increased amount
of traffic on a medium
– The only time that part of the medium is blocked is
during transmission/reception
• Services
UMTS - Features
• UMTS supports maximum theoretical data
transfer rates of 42 Mbit/s (with HSPA+)
• At the moment users in deployed networks
can expect a transfer rate of up to 384 kbit/s
for R99 handsets, and 7.2 Mbit/s for HSDPA
handsets in the downlink connection
UMTS - Features
• Data rates over radio interface:
– 2Mbps in fixed or in-building environments
– 384kbps in pedestrian or urban environments
– 144kbps in wide area mobile environments
– Variable data rates in large geographic area
systems (satellites)
Source: [3]
UMTS – Data rates
HSPA
HSDPA
• HSDPA - High-Speed Downlink Packet Access
- is an enhanced 3G (third generation) mobile
telephony communications protocol in the
High-Speed Packet Access (HSPA) family
• HSDPA allows for higher data rates in UMTS
networks
• Current HSDPA deployments support downlink speeds of 1.8, 3.6, 7.2 and 14.0 Mbit/s
HSDPA
• The first phase of HSDPA has been specified
in the 3rd Generation Partnership Project
(3GPP) release 5:
– Up to 14Mbps
• The second phase of HSDPA is specified in
the 3GPP release 7 and has been named
HSPA Evolved:
– Up to 42Mbps
– MIMO
Source: [1]
HSDPA
HSDPA - Features
• Fast downstream throughput:
– Data rates up to 10 Mbps
– Peak data rates even 14Mbps, with MIMO even
~20Mbps
• Significant capacity increase (vs UMTS):
– 3-4 times improved system capacity
– 1-2 times improvement for „best-effort” packet
data
– Improved capacity for streaming services (50%)
HSDPA – How it is done
• Adapting to environment with adaptive
modualtion and coding
• Fast channel scheduling with fast quality
feedback
• MIMO
• Fast retransmissions
• Higher order modulations (QPSK+16QAM)
• More efficient processing
HSDPA – Categories
HSUPA
• HSUPA - High-Speed Uplink Packet Access - is
an enhanced 3G (third generation) mobile
telephony communications protocol in the
High-Speed Packet Access (HSPA) family
• HSUPA allows for higher data rates in UMTS
networks
• Current HSUPA deployments support up-link
speeds up to 5.76 Mbit/s
• Works similar to HSDPA but in uplink
direction
HSPA+
• HSPA - Evolved High-Speed Packet Access
(HSPA) family
• Provides provides HSPA data rates up to 56
Mbit/s on the downlink and 22 Mbit/s on the
uplink with MIMO technologies and higher
order modulation (64QAM)
• The 56 Mbit/s and 22 Mbit/s represent
theoretical peak sector speeds. The actual
speed for a user will be lower
HSPA+
• Main enhancements in comparison to HSPA:
– 64QAM in DL with (1x2) SIMO
– 16QAM in DL with (2x2) MIMO
– 16QAM in UL
– 64QAM in DL with (2x2) MIMO
HSPA+ vs WiMAX
Source: [4]
HSPA+ vs WiMAX
LTE
Comparison of LTE Speed
LTE
• LTE - Long Term Evolution - is the latest
standard in the mobile network technology tree
• The LTE bases on a another radio interface than
GSM/UMTS networks
• Uses Orthogonal Frequency Division Multiplexing
(OFDM) for downlink
• Uses Single Carrier Frequency Division Multiple
Access (SC-FDMA) for uplink
• Uses Multi-input Multi-output(MIMO) for
enhanced throughput
LTE
LTE - features
• High spectral efficiency
– OFDM in Downlink, Robust against multipath interference & High
affinity to advanced techniques such as Frequency domain channeldependent scheduling & MIMO
– DFTS-OFDM (“Single-Carrier FDMA”) in Uplink, Low PAPR, User
orthogonality in frequency domain
– Multi-antenna application
• Very low latency
– Short setup time & Short transfer delay
• Support of variable bandwidth
– 1.4, 3, 5, 10, 15 and 20 MHz
Advantages of LTE
LTE – Major Parameters
LTE – User Equipement Categories
LTE Advanced
LTE vs LTE Advanced
LTE Advanced
• LTE Advanced – evolution of LTE towards
improved data bandwidth
• LTE Advanced – 3GPP project Releases 10 and
beyond
•
•
•
•
Finalized by 3GPP in March 2011
LTE Advanced is backward compatible with LTE
100 MHz aggregated bandwidth
3.3 Gbit peak download rates per sector of the
base station under ideal conditions
LTE Advanced - features
• Coordinated multipoint (CoMP) transmission
and reception
• UE Dual TX antenna solutions for SU-MIMO and
diversity MIMO
• Scalable system bandwidth exceeding 20 MHz,
up to 100 MHz
• Carrier aggregation of contiguous and noncontiguous spectrum allocations
• Flexible spectrum usage
• Cognitive radio
LTE Advanced - features
• Automatic and autonomous network
configuration and operation
• Support of autonomous network and device
test, measurement tied to network
management and optimization
• Enhanced precoding and forward error
correction
• Interference management and suppression
• Asymmetric bandwidth assignment for FDD
• Hybrid OFDMA and SC-FDMA in uplink
• SONs, Self Organized Networks methodologies
• Multiple carrier spectrum access.
Application example
Application example
GSM module - features
•
•
•
•
•
•
Tri-band GSM/GPRS SMT module
Size 33x33x3 mm !
An embedded TCP/IP protocol stack
Control via AT command
Supply voltage 3.4 … 4.5 V
Data rates:
– GPRS: 85.6 kbps in downlink
– CSD up to 14.4 kbps
• Many interfaces: SPI, GPIO, antena, SIM card, serial
interface, 2 x analog audio interface
Thank you for your attention
References
[1] www.wikipedia.org
[2] Lundmark T., „ WiMAX - a sneak preview”, TietoEnator
[3] Michaud F., „GPRS & EDGE « First steps toward Wireless data »”
[4] Sridhar Iyer, „ WiMAX: IEEE 802.16 - Wireless MANs”,
http://www.it.iitb.ac.in/~sri
[5] http://www.rfcafe.com/references/electrical/gsm-specs.htm
[6] http://gsmfordummies.com/tdma/tdma.shtml
[7] http://www.transanatolia.eu/analyses/wireless%20networks/edge1.pdf
[8]
http://www.cs.ucy.ac.cy/courses/EPL657/pitsillides_slides_2009/EPL%206
57%20UMTS-protocols%20and%20architecture.pdf
[9] http://cp.literature.agilent.com/litweb/pdf/5990-6706EN.pdf