BY:- VATSALYA SAXENA Mobile communication generations
Jun 28, 2015
BY:- VATSALYA SAXENA
Mobile communication generations
Overview
Communication generations
1G 2G 3G 4G
First Generation Cellular Systems
•
First generation (1G) of cellular systems introduced in the late 1970s and early 1980s
1G systems were based on analogue communication in the 900MHz frequency range
Voice transmission only
The most prominent 1G systems are Advanced Mobile Phone Systems (AMPS) - AmericaNordic Mobile Telephone (NMT) - FranceTotal Access Communications System (TACS) – UKJan 1985 Vodafone introduced the TACS system
First Generation Cellular Systems
Frequency Division Multiple Access (FDMA)
– Splits allocated spectrum into 30 channels, each channel is 30kHz
– Allocates a single channel to each established phone call
– Ineffective methods since each analogue channel can only be used by one user at a time
First Generation Cellular Systems
Frequency Division Multiple Access (FDMA)
First Generation Cellular Systems
• LIMITATIONS
– Ineffective methods since each analogue channel can only be used by one user at a time
– FDMA does not take full advantage of available spectrum
Actual data transfer speed vary from 2.9kbps to 5.6kbps which is very low
2G-TECHNOLOGY
• GSM(TDMA -based)
• IS-95(CDMA-based)
• PDC(TDMA-based) used in Japan
• iDEN (TDMA-based) used in United states
• IS-136 aka D-AMPS (TDMA-based)
GSM System – Radio Interface
• Base frequency: 900MHz
• Channel spacing 200kHz
• Time Division Multiple Access (TDMA)
• Hard Handover (MAHO)
• Maximum Bandwidth available: 9600 bits per second
GSM System – Multiple Access
Time Division Multiple Access (TDMA)
– Allows larger transmission rates than in an FDMA system
– Based on the idea to break individual frequencies into 8 timeslots of is 0.577 ms length (total 4.615ms) – these are referred to as a frame
– Each mobile device uses a particular slot different from slots used by other users
– Information transmitted in one slot is referred to as burst
– TDMA requires timeslot synchronisation
GSM System – Multiple Access
Time Division Multiple Access (TDMA)
– Guard Time: Interval between bursts used to avoid overlapping– Preamble: First part of the burst– Message: Part of burst that includes user data – Postamble: Last part of burst – used to initialise following burst
Slot 1 Slot 2 Slot 8 Slot 8Slot 1
Frame 1 Frame N
Multiframe
Guard Time Preamble Message Postamble Guard Time
Slot
Slot i ……..
GSM System – Multiple Access
Time Division Multiple Access (TDMA)
Frequency
Time
GSM-Supplementary Services
– User Identification– Emergency Calls– Call Hold– Advice of Charge– Call Barring– Call Forwarding– Multiparty calls
GSM System – Multiple Access
Code Division Multiple Access (CDMA)
– Multiple access technique used by american System (NOT used by the European GSM system)
– Based on the spread-spectrum technique
– Access technique realised before transmission by addition of a code that is independent of the data sequence
– Allows many devices to transmit simultaneously in the same frequency band
GSM System – Multiple Access
• Code Division Multiple Access (CDMA)
Code
Frequency
Time
Channel 1
Channel 2
Channel 3
Channel N
GSM System – Multiple Access
Code Division Multiple Access (CDMA)
– CDMA provides protection against multipath fading interference, privacy, interference rejection, anti-jamming capability, low probability of interception and allows macrodiversity
Handover
– Mobile-assisted handover (MAHO) as mobile measure signal strength but network-controlled as the network makes decision
Second Generation Cellular Systems
• Advantages-
• Phone conversations were digitally encrypted
• 2G systems were significantly more efficient allowing for far greater mobile phone penetration levels
• 2G introduced data services for mobile starting with SMS
• By a large majority of companies using the same technology the availability to communicate across the infrastructures can be achieved (known as Roaming)
What Next….?
•
3G-spacifications
• Technical specifications were made available under the name IMT-2000 by ITU
• Minimum transmission rates of 144 kbps in mobile (outdoor) and 2 Mbps in fixed (indoor) environments
• Three of the five approved standards-• CDMA2000 • TD-SCDMA• WCDMA
Difference between 2G and 3G Technology
• Cost
• Data Transmission
• Function
• Frequencies
• Implication
• Speed
3G -TECHNOLOGY
• The main technological difference that distinguishes 3G technology from 2G technology is the use of Packet switching rather than circuit switching for data transmission
• CDMA2000-1X delivers theoretical maximum data speeds of up to
307 kbit/s. • 3.5G, 3G+ or turbo 3G, which allows networks based on Universal
Mobile Telecommunications System (UMTS) to have higher data
transfer speeds and capacity. • 3GPP standards introduce a maximum downlink speed of 42Mbps
Limitations of 3G
Difficulty of CDMA to provide higher data rates
Need for continuously increasing data rate and
bandwidth to meet the multimedia requirements
Limitation of spectrum and it’s allocation
Inability to roam between different services
To introduce a better system with reduces cost
4G - Technology
• 3G technology with more bandwidth and services
• . The first two commercially available technologies billed as 4G were the WiMAX standard and the LTE standard
• 4G networks are defined as networks that will offer speeds from 100 Mbps to 1 Gbps, providing robust performance for the most bandwidth intensive applications, such as high quality streaming video
• WiMAX stands for Worldwide Interoperability of Microwave Access previously worked as fixed wireless facility under the 802.16e band. Now the modified standard 802.16m has been developed
4G-Technology
• LTE is developed on radio waves technology.
• LTE is using MIMO (Multiple input multiple output)
References
• H yumiba et al:overview of IMT-2000 network systems,Ntt DoCoMo tech. journal,6,4,p.8-13(1999)
• K. yamamoto et al:Core network technologies. Ntt docomo tech. journal,3,3,p.16-30(2001)
• www.google.com • www.en.wikipedia.org/wiki/4G• www.4g.co.uk• www.uscwc.com/4GReport• www.four-g.net/
QUERIES....???
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