Tugas Pertemuan ke 2
Multiple Access Technology
Mata Kuliah TEKNOLOGI MOBILE
Disusun Oleh : R. Moh Zuhdhi Malik
NIM 205411152
SEKOLAH TINGGI MANAJEMEN INFORMATIKA DAN KOMPUTER
AKAKOM YOGYAKARTA
Mobile phone or cellular technology
Mobile phone or cellular technology is widely used and is based upon the concept of frequency re-use by the application on a series of coverage cells. Mobile phone or cellular telecommunications technology has been in widespread use since the early 1980s.
Development of cellular communications
Although the basic concepts for cellular communications technology were proposed in the 1940s it was not until the mid-1980s that the radio technology and systems were deployed to enable widespread availability.
– it had taken 12 years since the first network was launched. By comparison it had taken over 100 years for the same figure to be reached for wired telephone connections. Then by 2015 more than 7 billion mobile subscriptions (for all technologies) were active. This is a major feat when it is realized that the global population was just over 7 billion.
Cellular telecommunications generations
1G at 1979 focus in Mobile voice
2G at 1991 focus in Mobile voice
3G at 2001 focus in Mobile Broadband
4G at 2009 focus in Mobile Broadband
5G at 2020 focus in Ubiquitous connectivity
Key cellular communications concepts
cellular telecommunications technology is based around the concept of using a large number of base stations each covering a small area or cell. With each base station communicating.
A cellular communications system has a number of different areas, each of which performs a different function
Mobile handset or user equipment, UE: The user equipment or mobile phone is the element of a mobile communications system that the user sees.
Radio access network, RAN: The radio access network is at the periphery of the cellular communications system. It provides the link to the user equipment from the cellular network
Core network: The core network is the hub of the cellular communications system. It manages the overall system as well as storing user data, manages access control links to the external world and provides a host of other functions.
TDD FDD Duplex Schemes
The forms of duplex transmission used for cellular technologies including FDD (Frequency Division Duplex) and TDD (Time Division Duplex). One of the key elements of any radio communications system is the way in which radio communications are maintained in both directions. Terms including simplex, duplex, frequency division duplex, FDD, and time division duplex, TDD, are all methods that can be used.
Transmission control schemes
- Simplex: Although the definition of simplex is not always clear the ANSI (American National Standards Institute) definition for a simplex transmission, is one that can only occur in one direction.
- Half duplex: This is a duplex scheme whereby communication is possible in two directions, but communication is only possible in one direction at a time. If one transmitter is transmitting, the other one must wait until the first stops before transmitting.
- Full duplex: Full duplex, which is sometimes referred to simply as duplex is a scheme whereby transmissions may be sent in both directions simultaneously. There are two ways of achieving this. One is to use frequency separation (frequency division duplex, FDD, and the other is to use time, time division duplex, TDD.
Frequency division duplex, FDD
Frequency division duplex, FDD, uses the idea that the transmission and reception of signals are achieved simultaneously using two different frequencies. Using FDD it is possible to transmit and receive signals simultaneously as the receiver is not tuned to the same frequency as the transmitter as shown
The spectrum used for FDD systems is allocated by the regulatory authorities. As there is a frequency separation between the uplink and downlink directions, it is not normally possible to reallocate spectrum to change the balance between the capacity of the uplink and downlink directions if there are changing capacity requirements for each direction.Time division duplex, TDD
The other system uses only a single frequency and it shares the channel between transmission and reception, spacing them apart by multiplexing the two signals on a time basis. Time Division Duplex, TDD, is used with data transmissions (data or digitised voice), transmitting a short burst of data in each direction. As the transmission periods are relatively short no time delay is noticed on voice transmissions resulting from the time delays introduced by using TDD.
Inside a Cellphone
Mobile phone contents:
Radio frequency — receiver and transmitter
This area of the mobile phone contains all the transmitter and receiver circuits
- Digital signal processing
undertake all the signal processing. Processes such as the radio frequency filtering and signal conditioning at the lower frequencies are undertaken by this circuitry.
- Analogue / digital conversion
Another crucial area of any mobile phone design is the circuitry that converts the signals between analogue and digital formats that are used in different areas. The radio frequency sections of the design use analogue techniques, whereas the processing is all digital.
- Control processor
The control processor is at the heart of the design of the phone. It controls all the processes occurring in the phone from the MMI (Man machine interface) which monitors the keypad presses and arranging for the information to be displayed on the screen.
- SIM or USIM card
- Power control and battery
