chapter 2 cellular wireless technology

Chapter 2Cellular wireless technology

Cellular wireless technology• Introduction

– 1G (1st Generation)• 1970’s – microprocessor inventions + digitization

of control link from mobile phone and cell site.• Launch by US – called as AMPS (Advanced

Mobile Phone System)• Access technology – FDMA technology, can make

voice call within one country.

Cellular wireless technology• Introduction (Cont.)

– 2G (2nd Generation)• Late 1980’s• Digitized both control link and voice signal• GSM (Global System for Mobile Communication)• Access technology – Based on TDMA technology

– 2.5G (2nd Generation)• 2G evolved to medium data transmission rate (about

100kbit/s)• High Speed Circuit Switched Data (HSCSD), a circuit

switched data communication extension of GSM with data transmission rate up to 76.8 kbit/s

• General Packet Radio System (GPRS), a packet switched data communication extension of GSM with data transmission rate of 115.2 kbit/s


– 2.75G (2nd Generation)• 2G evolved to broadband data transmission rate

(up to about 400kbps)• Enhanced Data rates for Global Evolution (EDGE),

faster data communication channels resulting from more efficient radio signal modulation

• EDGE/ECSD (Enhanced Circuit Switched Data) for circuit switched data communication

• EDGE/EGPRS (Enhanced GPRS) for packet switched data communication.


– 3G (3rd Generation)• Digital transmission• Compatible with GSM/EDGE• New base station technology for 2G-2.5G to

achieve broadband data transmission rates• 144 kbps - 384 kbps data transmission rate for

high-mobility and high coverage• Up to 2 Mbps for low-mobility and low coverage• Both circuit switched and packet switched data

communication.


– 3.5G (3rd Generation)• 3G evolved higher broadband data transmission

rates (up to 20 Mbit/s)• High Speed Downlink Packet Access (HSDPA)

which– a. is based on techniques such as adaptive

modulation and hybrid Automatic Repeat Request (ARQ) to achieve high throughput, reduce delay, and achieve high peak rates.

– b. relies on a new type of data communication channel


– 4G and Beyond (4th Generation and Beyond)• Wireless networks with cellular data rates of 20

Mbits/second and beyond.• Wireless World Research Forum (WWRF) for

research in research institutes and telecommunication

• Companies on wireless communications beyond 3G

• Many new technologies and techniques (multiplexing, intelligent antennas, digital signal processing)

• Integration of wireless cellular technologies with other wireless network technologies

Cellular wireless technology• GSM/GPRS/EDGE

– GSM• the most deployed wireless network for cellular mobile

telephony in the world.• considered to be a second generation (2G) mobile phone

system, since it was the first mobile phone protocol that employed digital signaling and speech channels

• GSM networks operate mostly in the 900 MHz or 1800 MHz bands.

• Data transmission rate - only 9600 bit/s or 14,400 bit/s with an improved codec for the air interface.

• More users of GSM – data transmission had to be increased.• Using HSCSD (High Speed Circuit-Switched Data)

technology - theoretical data transmission rate of up to 76,800 bit/s (8×9600 bit/s) for uplink or downlink can be achieved by using ‘channel bundling’ to combine several existing time slots in the air interface


– GSM (Cont.)• Existing GSM networks can be extended to support HSCSD

by using modified base stations and specially designed mobile telephones.

• The basic services voice transmission, call forwarding, roaming, and the SMS messaging service were implemented in 1992-1996

• In 1996 and later supplementary services were added, including conference calls, call handover, call number negotiation and GSM in the 1800-MHz frequency band.

• In the next development step these services were augmented with the functions of the SIM Application Toolkit, HSCSD and GPRS.


– GSM (Cont.)• System architecture

Figure gsm1. The architecture of a GSM Public Land Mobile Network (PLMN)


– GSM (Cont.)• System architecture (Cont.)

– A Base Station Subsystem (BSS) consists of» a Base Station Controller (BSC)» at least one radio access point or Base Transceiver

Station (BTS) for Mobile Stations (MS), which are mobile phones or other handheld devices (for example PDA computers) with phone interface.



– A BTS, with its aerial and associated radio frequency components, is the actual transmission and reception component.

– A Network Cell is the area of radio coverage by one BTS. One or more BTSs are in turn managed by a BSC.

– A network cell cluster covered by one or several BSSs can be managed as a Location Area (LA).

– All these BSSs must however be controlled by a single MSC.



Figure gsm3. The GSM network architecture for a single MSC controlled Service Area

ME = Mobile Equipment

BTS = Base Receiving Station

BSC = Base Station Controller

MSC = Mobile Switching Center

VLR = Visitor Location Register

OMC = Operation and Maintenance Center

AuC = Authentication Center

HLR = Home Location Register

EIR = Equipment Identity Register

SMSC = Short Message Service Centre


– GSM (Cont.)• Network and switching subsystem (NSS)

– NSS consists of the Mobile Switching Center (MSC) and the Visitor Location Register (VLR). A MSC manages multiple BSSs and is responsible for

» setting up, managing and shutting down connections,» handling call charges» supervising supplementary services, such as call

forwarding, call blocking and conference calling.– VLR contains information about all MSs currently within

range of the associated MSC. – This information is needed for routing a call to a particular

MS (mobile telephone) via the proper BSS and radio cell. – The VLR also maintains a list of MSs belonging to

subscribers of other GSM networks. Such subscribers have logged or roamed into the network of the associated MSC.


– GSM (Cont.)• Network and switching subsystem (NSS)

– The area covered by a MSC is actually called a MSC/VLR Service Area ,which can consist of several LAs.

• Operation Subsystem (OSS)– The OSS consists of

» the Operation and Maintenance Center (OMC)» the Authentication Center (AuC),» the Home Location Register (HLR)» the Equipment Identity Register (EIR)

– OMC is responsible for» regular network operation» subscriber administration » call billing.


– GSM (Cont.)• AuC is the security component on the network side. • AuC generates and manages all cryptographic keys and

algorithms needed for network operation, especially for authentication of the MSs (i.e., the SIMs).

• HLR contains all of the subscriber data as well as the localization data for each of the MS.

• EIR contains essential data, such as the serial numbers of all MSs represented in the network.

• OSS also controls the Short Message Service Centre (SMSC) for transmission of SMS messages.

• SMSC need information in HLR for the routing of SMS messages.


– GPRS• The General Packet Radio System (GPRS) is an extension

of the original GMS system with the purpose is to provide a packet switched data service with a high data transmission rate.

• A maximum data transmission rate of 115.2kbit/s can be achieved by bundling eight available time slots, each of which with a capacity of 14,400 kbit/s.

• GPRS forms a basis for mobile data communications services based on the Internet protocol (IP).


– GPRS• GPRS network services are classified as follows:

a. Point to Point (PTP) services– PTP Connectionless Network Service (PTP-CLNS), based on

IP– PTP Connection Oriented Network Service (PTP-CONS),

based on X.25b. Point to Multipoint (PTM) services

– PTM Multicast (PTM-M), to all subscribers in a given area– PTM Group Call (PTM-G), multicast to a group, which may be

dispersed over a geographical area– IP Multicast (IP-M)

c. Bearer Service for SMS


– GPRS• System architecture

Figure gprs1. The GPRS network architecture for a single operator is a GSM network architecture(see Figure gsm1) augmented withSGSN = Serving GPRS Support Node,GGSN = Gateway GPRS Support Node, andGR = GPRS Register.



– The new GPRS component are:» the Serving GPRS Support Node (SGSN), which

coordinates the data packet exchange with the BSSs. The role SGSN for packet switched data communication is thus analogous to the role of MSC for circuit switched data communication



» the Gateway GPRS Support Node (GGSN), which is an interface to other packet switched data communication services, such as X.25 and IP. The GGSN transforms GPRS data packets into packets corresponding to the other packet switched data communication services and vice versa. The SGSN is subordinate to a GGSN

» the GPRS Register (GR), which is analogous to and co-located with the HLR, manages all of the data related to specific GPRS subscribers. GR stoires routing information and maps IMSI to Packet Data Network (PDN) address, for example an IP address.


– EDGE• Enhanced Data rates for GSM Evolution (EDGE) also known

as Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT- SC).

• extension on top of standard GSM• EDGE/EGPRS is a superset to GPRS and can function on

any network with GPRS deployed on it, provided the carrier implements the necessary upgrade.

• EDGE requires no hardware or software changes to be made in GSM core networks.


– EDGE• System architecture

– EDGE enhancement of circuit switched data communication is called ECSD (Enhanced Circuit Switched Data), which updates HSCSD for EDGE modulation in the radio interface.

– EDGE enhancement of packet switched data communication is called EGPRS (Enhanced GPRS).

– BTS and MS devices must be EDGE capable in a GSM/GPRS system architecture.

– BTS units must be enhanced with EDGE Transcoding Units (EDGE TRU) due to the higher data communication rates.


– EDGE• System architecture

Figure edge1. GPRS system architecture enhancement for EGPRS.

Cellular wireless technology• WCDMA/HSPDA

– WCDMA


– WCDMA

• 3G mobile telecommunications networks.

• Radio channels are 5MHz wide.

• Chip rate of 3.84 Mcps

• Supports two basic modes of duplex: frequency division and time division. Current systems use frequency division, one frequency for uplink and one for downlink. For time division, FOMA uses sixteen slots per radio frame, whereas UMTS uses fifteen slots per radio frame.


– WCDMA• Employs coherent detection on both the uplink and downlink

based on the use of pilot symbols and channels. • Supports inter-cell asynchronous operation. • Variable mission on a 10 ms frame basis. • Multicode transmission. • Adaptive power control based on SIR (Signal-to-Interference

Ratio). • Multiuser detection and smart antennas can be used to

increase capacity and coverage. • Multiple types of handoff (or handover) between different

cells including soft handoff, softer handoff and hard handoff.

Cellular wireless technology

• WCDMA/HSPDA– HSDPA

• High-Speed Downlink Packet Access (HSDPA) is an enhanced 3G (third generation)

• High-Speed Packet Access (HSPA) family.• Allows networks based on Universal Mobile

Telecommunications System (UMTS) to have higher data transfer speeds and capacity

• Current HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.4 Mbit/s.

• Further speed increases are available with HSPA+, which provides speeds of up to 42 Mbit/s downlink.


• WCDMA/HSPDA– HSDPA

• Hybrid automatic repeat-request (HARQ)• Fast packet scheduling• Adaptive modulation and coding• Reduces latency and round trip time for applications


• IS-95/CDMA2000-1x, EC-DV, EV-DO– IS-95

• Interim Standard 95 (IS-95) is the first CDMA-based digital cellular standard pioneered by Qualcomm

• The brand name for IS-95 is cdmaOne. IS-95 is also known as TIA-EIA-95.

• 2G Mobile Telecommunications Standard that uses CDMA, a multiple access scheme for digital radio, to send voice, data and signaling data (such as a dialed telephone number) between mobile telephones and cell sites.

http://en.wikipedia.org/wiki/CDMA


• IS-95/CDMA2000-1x, EC-DV, EV-DO– CDMA2000-1x

• CDMA2000 is a hybrid 2.5G / 3G technology of mobile telecommunications standards that use CDMA.

• CDMA2000 is considered a 2.5G technology in 1xRTT and a 3G technology in EVDO

• The CDMA2000 standards CDMA2000 1xRTT, CDMA2000 EV-DO, and CDMA2000 EV-DV are approved radio interfaces for the ITU's IMT-2000 standard and a direct successor to 2G CDMA, IS-95 (cdmaOne).

• The designation "1x", meaning "1 times Radio Transmission Technology", indicates the same RF bandwidth as IS-95: a duplex pair of 1.25 MHz radio channels.


• IS-95/CDMA2000-1x, EV-DV, EV-DO– EV-DV

• CDMA2000 EV-DV (Evolution-Data/Voice) • downlink (forward link) data rates up to 3.1 Mbit/s and uplink

(reverse link) data rates of up to 1.8 Mbit/s.• support concurrent operation of legacy 1x voice users, 1x

data users, and high speed EV-DV data users within the same radio channel.

http://en.wikipedia.org/wiki/Legacy


• IS-95/CDMA2000-1x, EV-DV, EV-DO– EV-DO

• Evolution-Data Optimized or Evolution-Data only• telecommunications standard for the wireless transmission of

data through radio signals, typically for broadband Internet access.

• uses multiplexing techniques including CDMA as well as TDMA to maximize both individual user's throughput and the overall system throughput.


• WLAN– Wireless local area network that links two or more computers or

devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area.

– This gives users the mobility to move around within a broad coverage area and still be connected to the network.

– For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops

chapter 2 cellular wireless technology

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