Evolution Of Mobile Communication

Table of Contents

Cellular System

Cordless Telephone System (CT)

Wide Area Paging Systems

Trends for Cellular Radio and Personal Communications

A mobile conversation is a two-way communication between users at different sites using their mobile devices. It was initially a voice-based system, but as time went on, data became a part of it. Cellular phones offer a wide range of services, including E-mails, internet, short messages, electronic address books, games, calculators, and access to the Internet. There are more efforts to get users interested in commercial products. Mobile phones can be carried anywhere by subscribers within the 825-845 MHz spectrum.

Advanced Mobile Phone System, or AMPS for short, was a first-generation digital cellular network that had a data rate as high as 19.2 Kbps. Global System for Mobile communications, or GSM, and Personal Communication Service, also known as PCS are both second-generation wireless technologies that offer a 9.6 kbps data rate.

Due to revolutions in fields such as:

RF circuit fabrication

Large scale circuit integration

Digital circuit design

Miniaturization technology

Mobile communication has a significant impact on personal communication. Bell Laboratories worked on the development of cellular technologies between 1960-1970. Wireless communication grew exponentially. The use of wireless technology is increasing in daily life. Personal and cell communications have been a major factor in revolutionizing the communication industry. Below is a graph that compares mobile communication with other technologies.

Cellular communication technology has developed slowly and globally. It is a technology that has been around for a longer time and with fewer competitors. The graph shows a significant increase.

Amplitude Modulation Systems (AM) were used by police radios in 1934 to transmit. Early cellular networks were plagued with vehicle ignition noise. In the 1960s, mobile phone users could not dial direct telephone numbers. The majority were also not connected to PSTN. Wireless communications are gaining popularity worldwide. Qualcomm, inc. created a better cellular-mobile system using Code Division Multiple Access.

IS-95 is a mobile system that allows a high number of users. It uses Direct Sequence Spread Spectrum technology (DSSS). CDMA cellular phones were free of interference and had better call quality compared to the 1G AMPS cellular systems. The following are some of North America’s, Japan’s and Europe’s mobile standards.

AMPS – Analog Mobile Phone System.

USDC – US Digital Cellular.

CDPD is Cellular Digital Packet Data.

Interim Standard-95, also known as IS-95, is a communications standard.

JTACS is the Japanese Total Access Cellular Systems.

PDC – Pacific Digital Cellular.

NIT is the Nippon Telephone and Telegraph Company.

PHS-Personal Handy Phone System

ETACS is the European Total Access Cellular System.

GSM is the Global System for Mobile.

A cordless telephone, otherwise known as a CT2, is a phone that does not require a physical connection to the phone line. (CT2)

DECT is Digital European Cordless Telephone.

The cellular, PCS and cordless systems all have their own unique features and advantages in mobile communication. So, the switch from analog mobiles to digital mobiles was made over several years. Digital cell telephony, which has many technical advantages and includes cellular coverage, is now widely used around the globe. Cellular radio communication examples.

Cellular telephone system.

Cordless Telephones (CT) System.

Paging System

Below are some examples.

Cellular SystemThe cell phone system connects a Public Switched Phone Network (PSTN), with any distant/near users, provided they are within the range of radio signals. The following is an example of a basic cell system. The Mobile Telephone Switching Office, or MTSO, connects mobile units (also called parties) to PSTN. Each cell is equipped with a base station, including a transceiver/antenna, control circuitry, and antenna. Base stations can handle many full-duplex cellular communications. Mobile switching centers can handle up to 5000 telephone conversations at once and 100,000 subscribers/users of cellular services in a single network. Common Air Interface(CM) specifies 4 channels for cellular communication. The four channels are:

Forward Control Channels

Reverse control channels (RCC)

Forward Voice Channels FVC

Reverse Voice Channels (RVC).

Setup channels is another name for the control channels. These channels will receive and send data messages containing requests for service and call initiators.

Forward Control Channels also known as beacons broadcast continuously the traffic requests of the mobile devices within the cell system. The cell phone scans control channels as soon as it is turned on, looking for the strongest base station signal. The mobile switching center changes the power transmitted of the mobile device and the base station’s channel as the call progresses. This allows the call to be maintained even if the mobile phone is moving.

The call continues to run regardless of frequency changes. The ‘Hand Off Technique’ is used to continue the call without terminating it. As soon as the mobile moves from the cell’s base station or base station it enters, the next base of that cell will take the call. It is a relay system that takes place between several basestations of the cellular network to support the call.

A request signal is sent by the mobile unit whenever it initiates a phone call. By receiving this request, a mobile unit will transmit their Mobile Identification Numbers (MIN), as well the telephone numbers of the subscribers they have called and the Electronic Serial Numbers (ESN). The MSC will then check that the mobile unit’s signals are valid and connect the subscriber to the PSTN.

Mobile communication is used to establish a call, keep it active, and then terminate the call when its over. The mobile communication allows for communication between subscribers despite the large distance.

The cordless telephone system is a full-duplex system. It is designed to connect the portable handsets to a base station dedicated to one specific telephone line. Public Switched Telephone Networks are used to call this number. In the 1980s, cordless phone systems of 1G generation were introduced. But it only covered a distance of a few metres.

Cordless Telephone System (CT) Later, with the second-generation (2G) cordless system, distance was no longer an issue and subscribers could use cordless telephones in mobile environments. The system worked only when the base station covered the subscribers.

Cordless systems can also be used in conjunction with paging systems. This allows the roaming subscriber to first receive a page and then respond with a cordless phone. In the above simple cordless setup, the cordless phone is connected to PSTN by the basestation (fixed port). The cordless handset is connected wirelessly to its base station. Analog Cf & Digital CT are both cordless system types. These cordless systems used to be analog (AnalogCT). They enabled mobility with limited distances. However, they were not without their flaws.

Call qualitys

Interference of waves

Digital cordless systems (Digital CT) were needed to solve these problems. The voice quality was comparable to that of a wired system. The main features of CT2 systems are

ADPCM is a 32-kb/sec technique that digitalizes voice signals.

Bit stream compression facility.

Final bitstream transmission through Gaussian-Frequency Shift (GFSK).

Immune against errors

Data transmissions are supported up to 32 Kb/sec.

Time Division Duplex Access (TDD) is a technique that allows traffic to be separated.

The CT2+ standard, which was later developed, is used to determine the mobility status. These systems transmit short messages. The message sent can be a numeric or alphanumeric data. News headlines, stock quotes and faxes are also included in paging systems. You can send it to a subscriber using a modem with the paging access number or by dialing a phone keypad. This message is known as a page.

In a method called’simulcasting ‘, the wide pager systems send a single page simultaneously from each basestation. Below are the key performance metrics that can be used to make decisions in hand-off situations (mobility).

Probability that a call will be blocked

Probability that a call will drop

Probability that the call will be completed

Handoff delay

Handoff rate

Probability that a handoff is not completed

Probability of blocking a handoff

Interruption time duration

Handoff Probability

There are two main strategies to calculate when the handoff occurs:

Relative Signal Strength Method

Relative Signal Strength with Hysteris Method

Relative Signal Strength with Threshold Method

Prediction techniques.

A paging centre connects a MIN to multiple paging termini.

Wide Area Paging SystemsPaging Systems allow subscribers to communicate regardless of whether they are roaming or not. The system uses low data rates and requires high transmitter power in the order kilowatts.

As shown in the image above, cellular phones are capable of many functions. This includes pagers. Subscribers use it a lot to send short messages. The page or short message is sent to the subscriber no matter where he may be.

Important Terminologies:

Cellular: The smallest geographic area that is considered for mobile communications.

Base station: Base station is the device that connects mobile units to Mobile Switching Centers (MSCs). Base station: The base stations are located in each cell. They connect the mobile units of subscribers with the MSC.

Cell splitting: To ensure radio coverage in high-traffic areas, a cell larger than the average is split up into smaller cells.

Handoff: This is the process that occurs when the mobile unit moves to a new cell. It is done by handing the current call from the base to the transceiver at the cell of the mobile unit.

Cell sectoring is the division of a cell into multiple sectors. Cell sectoring: A cell can be divided in many sectors. The directional antenne should be aimed at each sector.

Umbrella pattern: A macrocell (large cell) is composed of a number of microcells (small cells). There will also be an interaction between the two.

Control Channels: These are used to send and receive information regarding the setting up of base stations for mobile units and cell bases.

Traffic channels: They can be used to transport data or audio between users.

Frequency re-use is an important concept for cellular communication. It allows efficient spectrum use. Frequency reuse is the process of using the same carrier frequencies by multiple cells in a cluster.

Fading occurs in radio propagation. It is common when mobile signaling environments have multiple paths.

Mobile Telecommunication Switching Office/Mobile Switching Center MTSO/MSO: This unit is responsible for connecting the base transceiver to the Public Switched Telephone Network.

Trends for Cellular Radio Systems and Personal CommunicationsWith the aid of digital signal processors, RF and network intelligence systems, subscribers can now enjoy a variety of services. Personal Communication Services started in United Kingdom. The allocated spectrum was 1800 MHz. The focus was on Personal Communication Networking.

PCN has the advantage that subscribers can make or receive calls regardless of whether they are roaming. Personal Communication Systems includes more features in the network and offers greater personalization.

Indoor wireless networks gained in importance when they improved the network connectivity of buildings. The European Telecommunications Standard Institute developed HIPERLAN, a standard compatible with indoor wireless standards.

International Telecommunications Union created a standard that is important for the world, called Future Public Land Mobile Telephone System. IMT-2000, also known as the third-generation (3G) standard, has several advantages.

Interoperability worldwide.

Integrate the cordless, cellular and paging mobile systems with LEO satellites into a single system.

Supports multiple functions.

The digital mobile system is well-known and widely used. Satellite mobile systems are equipped with paging services, data gathering, global roaming as well emergency communications. Network of LEOs satellites are one example.

The rapid growth of wireless personal communications systems has been facilitated by the technological advancements. Wireless networking technology will continue to evolve in order for it to be able meet even more demands and provide additional features within the wireless personal communications sector.