Wireless & Mobile Communication Freeha Azmat

Mobile Radio Communication In last 10 years, this industry is fueled by: Digital RF circuit Fabrication New Large Scale Circuit Integration Miniaturization Technologies which make portable radio equipment cheaper, smaller and more reliable

Electronics boom :

Evolution of Mobile Communication 1946: Mobile telephone services in 25 major American cities 120KHz of RF bandwidth in half duplex mode 1950 &1960: IMTS(Improved Mobile Telephone service) came which offered full duplex communication IMTS became saturated due to availability of less channels

1950 and 1960: AT &T labs and other telecom companies developed the theory and techniques for cellular radiotelephony : “The concept of breaking a coverage zone into small cells, each of which reuse portions of spectrum to increase spectrum usage at the expense of greater system infrastructure” AT &T proposed the concept of cellular mobile system to FCC in 1968,although the technology wasn’t present to implement the concept.

In 1983 FCC allocated 666 duplex channels (40MHz spectrum in 800MHz band) Additional 10MHz(166 channels) were allocated in 1989 which made the total spectrum of 50MHz

Frequency Allocation in the US for AMPS January, 2006

Evolution AMPS (Advance Mobile Phone Service) In 1970s,AT&T labs developed the first US cellular telephone system called the AMPS (Advance Mobile Phone Service) By mid 1960s,the FM bandwidth of voice transmission was cut to 30KHz ETACS(European Total Access Communication System) Developed in 1980s Identical to AMPS except the bandwidth was reduced to 25kHz

Evolution (Cont) USDC (US Digital Cellular System) : In 1991,the first digital cellular system hardware was installed in major US cities. Support 3 users in the same 30kHZ bandwidth CDMA (Code Division Multiple Access): Cellular system based on CDMA Can support variable users in 1.25MHz wide channel Improvement in capacity due to FM techniques

Major Mobile Radio Standards in North America January, 2006

Major Mobile Radio Standards in Europe January, 2006

Major Mobile Radio Standards in Japan January, 2006

Wireless Communications System Definitions: January, 2006

Wireless Communication System Definitions:

Types of Mobile Radio Systems: 1)Simplex Radio/TV broadcast 2)Half-Duplex push to talk and release to listen 3) Full Duplex: Cell Phone Full duplex requirement: FDD TDD

Frequency Division Duplexing(FDD) Simultaneous Radio transmission channels for the subscriber and base station. To facilitate FDD, it is necessary to separate the transmit and receive frequencies by about 5% of the nominal frequency.

Time Division Duplexing Share a single radio channel in time Portion of the time consumed from base station to mobile and vice versa Preferred for indoor or small area wireless applications Do you know why?

Comparison of FDD and TDD: FDD is efficient in case of symmetric traffic It makes radio planning easier because base stations do not hear each other. With TDD systems, guard bands between neighboring base stations is necessary TDD has a strong advantage where asymmetry of the uplink and downlink data speed is variable. As the amount of uplink data increases, more bandwidth can dynamically allocated to that and vice versa

Paging Systems Those communication systems that send brief messages to subscriber. The message may either be A numeric message An alphanumeric message A voice message The issued message is called Page. In modern Paging system, news headlines, stock quotations and faxes may be sent Paging systems vary on the basis of complexity and coverage area

A wide area Paging System Simulcast transmitters can be located in the same service area or in different cities and countries

A cordless Telephone system 1st generation Cordless Telephone systems 2nd Generation

A Cellular System January, 2006

Definitions/Acronyms CAI: Common Air Interface For communication between the base station and the mobile It has 4 different channels FVC: Forward Voice Channel (from base station to mobile) RVC: Reverse Voice Channel FCC: Forward Control Channel RCC: Reverse Control Channel ** Control channels are often called setup channels because they are involved in setting up a call and moving to unused channel **Control channels contain handoff instructions ** Control channels make up about 5% of the total channels January, 2006

Definitions/Acronyms (contd.) MSC: Mobile Switching Center also called MTSO: Mobile Telephone Switching office PSTN: Public Switched Telephone Network January, 2006

Call setup Procedure: 1.ESN(Electronic Serial Number): Is unique 32bit identification number embedded in a wireless phone by the manufacturer. Each time a call is placed, the ESN is automatically transmitted to the base station.ESN cannot easily be altered in the field.ESN can be checked electronically to prevent the fraud.

2.MIN(Mobile Identification number) Is 24 bit number corresponding to the actual 7 digit telephone number assigned by the cellular carrier exclusively to a phone, used for billing and for receiving calls. The MIN is paired with ESN. Theoretically both numbers are verified, and in combination, every time a call is placed in order to verify the legitimacy of the call and device

3.System Identification Number(SID) Is unique 5-digit number that has been assigned to identify the particular cellular carrier i.e. the service provider, from whom you are obtaining service. This number identifies your home system

How a Cellular Telephone Call is Made From Land line to Mobile MIN FCC MIN: mobile identification number Free channels RCC PSTN MSC MIN January, 2006

Timing Diagram Illustration for Call from Land line to Mobile Fig. 1.6 January, 2006

How a Cellular Telephone Call is Made From Mobile to Land line MIN/telephone # RCC MIN/telephone MIN: mobile identification number Free channels PSTN MSC January, 2006

Timing Diagram Illustration for Cal from Mobile to Land line Fig. 1.7 January, 2006

Frequency Reuse The problems with cellular concept was: Spectral congestion User capacity

Linear Cells as an Example of Frequency Reuse Total Band width (BW) is divided into three adjacent bands f1, f2 and f3 Such that BW = f1+f2+f3 f1 f2 f3 P I Cell 1 Cell 2 Cell 3 Cluster 1 Cluster 2

Cluster Size 3 Cell Cluster 4 Cell Cluster 1 2 3 4 1 2 3