List of Engineering Acronyms --قائمة الاختصرات للمفاهيم الهندسيه

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3GPP              Third Generation Partnership Project
AAS                Adaptive Antenna System
ACK               Acknowledgement (in ARQ protocols)
ACK-CH        Acknowledgement Channel (for WiMAX)
ACLR             Adjacent Channel Leakage Ratio
ACS               Adjacent Channel Selectivity
ACIR              Adjacent Channel Interference Ratio
ACTS             Advanced Communications Technology and Services
AM                 Acknowledged Mode (RLC configuration)
AMC              Adaptive Modulation and Coding
AMPR            Additional Maximum Power Reduction
AMPS            Advanced Mobile Phone System
AMR-WB      Adaptive MultiRate-WideBand
AP                  Access Point
ARIB              Association of Radio Industries and Businesses
ARQ               Automatic Repeat-reQuest
ATDMA          Advanced Time Division Mobile Access
ATIS               Alliance for Telecommunications Industry Solutions
AWGN           Additive White Gaussian Noise
BCCH             Broadcast Control Channel
BCH                Broadcast Channel
BE                   Best Effort Service
BER                Bit-Error Rate
BLER              Block-Error Rate
BM-SC           Broadcast Multicast Service Center
BPSK             Binary Phase-Shift Keying
BS                   Base Station
BSC                Base Station Controller
BTC                Block Turbo Code
BTS                Base Transceiver Station
CC                  Convolutional Code
CCCH            Common Control Channel
CCE               Control Channel Element
CCSA            China Communications Standards Association
CDD              Cyclic-Delay Diversity
CDF               Cumulative Density Function
CDM              Code-Division Multiplexing
CDMA           Code Division Multiple Access
CEPT             European Conference of Postal and Telecommunications Administrations
CN                 Core Network
CODIT           Code-Division Test bed
CP                  Cyclic Prefix
CPC                Continuous Packet Connectivity
CPICH            Common Pilot Channel
CQI                Channel-Quality Indicator
CQICH          Channel Quality Indication Channel (for WiMAX)
CRC               Cyclic Redundancy Check
C-RNTI          Cell Radio-Network Temporary Identifier
CS                  Circuit Switched
CTC               Convolutional Turbo Code
CW                Continuous Wave
DCCH            Dedicated Control Channel
DCH               Dedicated Channel
DCI                 Downlink Control Information
DFE                Decision-Feedback Equalization
DFT                Discrete Fourier Transform
DFTS-OFDM DFT-spread OFDM, see also SC-FDMA
DL                  Downlink
DL-SCH         Downlink Shared Channel
DPCCH          Dedicated Physical Control Channel
DPCH             Dedicated Physical Channel
DPDCH          Dedicated Physical Data Channel
DRS                Demodulation Reference Signal
DRX               Discontinuous Reception
DTCH             Dedicated Traffic Channel
DTX               Discontinuous Transmission
D-TxAA         Dual Transmit-Diversity Adaptive Array
DwPTS          The downlink part of the special subframe (for TDD operation).
E-AGCH        E-DCH Absolute Grant Channel
E-DCH           Enhanced Dedicated Channel
EDGE             Enhanced Data rates for GSM Evolution and Enhanced Data rates for Global Evolution
E-DPCCH      E-DCH Dedicated Physical Control Channel
E-DPDCH      E-DCH Dedicated Physical Data Channel
E-HICH          E-DCH Hybrid ARQ Indicator Channel
eNodeB          E-UTRAN NodeB
EPC                Evolved Packet Core
E-RGCH         E-DCH Relative Grant Channel
ErtPS              Extended Real-Time Polling Service
E-TFC            E-DCH Transport Format Combination
E-TFCI           E-DCH Transport Format Combination Index
ETSI               European Telecommunications Standards Institute
E-UTRA         Evolved UTRA
E-UTRAN      Evolved UTRAN
EV-DO           Evolution-Data Optimized (of CDMA2000 1x)
EV-DV           Evolution-Data and Voice (of CDMA2000 1x)
EVM              Error Vector Magnitude
FACH            Forward Access Channel
FBSS             Fast Base-Station Switching
FCC               Federal Communications Commission
FCH               Frame Control Header (for WiMAX)
FDD               Frequency Division Duplex
FDM              Frequency-Division Multiplex
FDMA           Frequency-Division Multiple Access
F-DPCH        Fractional DPCH
FEC               Forward Error Correction
FFT               Fast Fourier Transform
FIR                Finite Impulse Response
F-OSICH      Forward link Other Sector Indication Channel (for IEEE 802.20)
FPLMTS       Future Public Land Mobile Telecommunications Systems
FRAMES      Future Radio Wideband Multiple Access Systems
FTP               File Transfer Protocol
FUSC            Fully Used Subcarriers (for WiMAX)
FSTD            Frequency Shift Transmit Diversity
GERAN        GSM/EDGE Radio Access Network
GGSN          Gateway GPRS Support Node
GP                Guard Period (for TDD operation)
GPRS           General Packet Radio Services
GPS             Global Positioning System
G-RAKE      Generalized RAKE
GSM            Global System for Mobile communications
HARQ          Hybrid ARQ
HC-SDMA   High Capacity Spatial Division Multiple Access
H-FDD         Half-duplex FDD
HHO             Hard Handover
HLR              Home Location Register
HRPD           High Rate Packet Data
HSDPA         High-Speed Downlink Packet Access
HS-DPCCH High-Speed Dedicated Physical Control Channel
HS-DSCH    High-Speed Downlink Shared Channel
HSPA            High-Speed Packet Access
HS-PDSCH  High-Speed Physical Downlink Shared Channel
HSS              Home Subscriber Server
HS-SCCH    High-Speed Shared Control Channel
HSUPA         High-Speed Uplink Packet Access
ICIC             Inter-Cell Interference Coordination
ICS               In-Channel Selectivity
IDFT            Inverse DFT
IEEE             Institute of Electrical and Electronics Engineers
IFDMA        Interleaved FDMA
IFFT            Inverse Fast Fourier Transform
IMS             IP Multimedia Subsystem
IMT-2000    International Mobile Telecommunications 2000
IP                 Internet Protocol
IPsec            Internet Protocol security
IPv4             IP version 4
IPv6             IP version 6
IR                 Incremental Redundancy
IRC              Interference Rejection Combining
ISDN           Integrated Services Digital Network
ITU              International Telecommunications Union
ITU-R          International Telecommunications Union - Radio communications Sector
Iu                 The interface used for communication between the RNC and the core network.
Iu_cs            The interface used for communication between the RNC and the GSM/WCDMA circuit switched core network.
Iu_ps            The interface used for communication between the RNC and the GSM/WCDMA packet switched core network.
Iub                The interface used for communication between the NodeB and the RNC.
Iur                 The interface used for communication between different RNCs.
J-TACS         Japanese Total Access Communication System
LAN              Local Area Network
LCID             Logical Channel Index
LDPC            Low-Density Parity Check Code
LMMSE        Linear Minimum Mean Square Error
LTE                Long-Term Evolution
MAC             Medium Access Control
MAN             Metropolitan Area Network
MAP              Map message (for WiMAX)
MBFDD         Mobile Broadband FDD (for IEEE 802.20)
MBMS           Multimedia Broadcast/Multicast Service
MBS              Multicast and Broadcast Service
MBSFN         Multicast-Broadcast Single Frequency Network
MBTDD         Mobile Broadband TDD (for IEEE 802.20)
MBWA           Mobile Broadband Wireless Access
MCCH           MBMS Control Channel
MC                 Multi-Carrier
MCE               MBMS Coordination Entity
MCH               Multicast Channel
MCS               Modulation and Coding Scheme
MDHO           Macro-Diversity Handover
MIB                Master Information Block
MICH             MBMS Indicator Channel
MIMO            Multiple-Input Multiple-Output
ML                  Maximum Likelihood
MLD               Maximum Likelihood Detection
MLSE              Maximum-Likelihood Sequence Estimation
MME               Mobility Management Entity
MMS               Multimedia Messaging Service
MMSE             Minimum Mean Square Error
MPR                Maximum Power Reduction
MRC               Maximum Ratio Combining
MSC                Mobile Switching Center
MSCH             MBMS Scheduling Channel
MTCH             MBMS Traffic Channel
NAK                Negative Acknowledgement (in ARQ protocols)
NAS                Non-Access Stratum (a functional layer between the core network and the terminal that supports signaling and user data transfer)
NMT               Nordisk MobilTelefon (Nordic Mobile Telephony)
NodeB             NodeB, a logical node handling transmission/reception in multiple cells. Commonly, but not necessarily, corresponding to a base station.
nrtPS                Non-Real-Time Polling Service
OFDM             Orthogonal Frequency-Division Multiplexing
OFDMA          Orthogonal Frequency-Division Multiple Access
OOB                 Out-Of-Band (emissions)
OOK                On–Off Keying
OVSF              Orthogonal Variable Spreading Factor
PAN                 Personal Area Network
PAPR               Peak-to-Average Power Ratio
PAR                  Peak-to-Average Ratio (same as PAPR)
PARC               Per-Antenna Rate Control
PBCH               Physical Broadcast Channel
PCCH              Paging Control Channel
PCFICH           Physical Control Format Indicator Channel
PCG                 Project Coordination Group (in 3GPP)
PCH                 Paging Channel
PCI                  Pre-coding Control Indication
PCS                 Personal Communications Systems
PDC                 Personal Digital Cellular
PDCCH           Physical Downlink Control Channel
PDCP              Packet Data Convergence Protocol
PDSCH           Physical Downlink Shared Channel
PDSN             Packet Data Serving Node
PDN                Packet Data Network
PDU                Protocol Data Unit
PF                   Proportional Fair (a type of scheduler)
PHICH            Physical Hybrid-ARQ Indicator Channel
PHY                Physical layer
PHS                 Personal Handy-phone System
PMCH             Physical Multicast Channel
PMI                 Precoding-Matrix Indicator
PoC                 Push to Talk over Cellular
PRACH           Physical Random Access Channel
PRB                 Physical Resource Block
PS                    Packet Switched
PSK                 Phase Shift Keying
PSS                  Primary Synchronization Signal
PSTN               Public Switched Telephone Networks
PUCCH           Physical Uplink Control Channel
PUSC              Partially Used Subcarriers (for WiMAX)
PUSCH           Physical Uplink Shared Channel
QAM              Quadrature Amplitude Modulation
QoS                Quality-of-Service
QPP                Quadrature Permutation Polynomial
QPSK             Quadrature Phase-Shift Keying
RAB                Radio Access Bearer
RACE             Research and development in Advanced Communications in Europe
RACH             Random Access Channel
RAN               Radio Access Network
RA-RNTI        Random Access RNTI
RAT                 Radio Access Technology
RB                   Resource Block
RBS                 Radio Base Station
RF                   Radio Frequency
RI                    Rank Indicator
RIT                  Radio Interface Technology
RLC                 Radio Link Protocol
RNC                Radio Network Controller
RNTI               Radio-Network Temporary Identifier
ROHC             Robust Header Compression
RR                   Round-Robin (a type of scheduler)
RRC                Radio Resource Control
RRM               Radio Resource Management
RS                   Reference Symbol
RSN                Retransmission Sequence Number
RSPC              IMT-2000 radio interface specifications
RTP                 Real Time Protocol
rtPS                 Real-Time Polling Service
RTWP             Received Total Wideband Power
RV                   Redundancy Version
S1                   The interface between eNodeB and the Evolved Packet Core.
SA                  System Aspects
SAE                System Architecture Evolution
S-CCPCH      Secondary Common Control Physical Channel
SC-FDMA     Single-Carrier FDMA
SDMA            Spatial Division Multiple Access
SDO               Standards Developing Organization
SDU               Service Data Unit
SEM               Spectrum Emissions Mask
SF                   Spreading Factor
SFBC              Space-Frequency Block Coding
SFN                Single-Frequency Network or System Frame Number (in 3GPP)
SFTD              Space–Frequency Time Diversity
SGSN             Serving GPRS Support Node
SI                    System Information message
SIB                 System Information Block
SIC                 Successive Interference Combining
SIM                 Subscriber Identity Module
SINR               Signal-to-Interference-and-Noise Ratio
SIR                  Signal-to-interference ratio
SMS                Short Message Service
SNR                Signal-to-noise ratio
SOHO             Soft Handover
SR                   Scheduling Request
SRNS              Serving Radio Network Subsystem
SRS                 Sounding Reference Signal
SSS                 Secondary Synchronization Signal
STBC              Space–Time Block Coding
STC                Space–Time Coding
STTD              Space-Time Transmit Diversity
TACS              Total Access Communication System
TCP                Transmission Control Protocol
TC-RNTI        Temporary C-RNTI
TD-CDMA      Time Division-Code Division Multiple Access
TDD                Time Division Duplex
TDM               Time Division Multiplexing
TDMA            Time Division Multiple Access
TD-SCDMA   Time Division-Synchronous Code Division Multiple Access
TF                   Transport Format
TFC                Transport Format Combination
TFCI               Transport Format Combination Index
TIA                 Telecommunications Industry Association
TM                 Transparent Mode (RLC configuration)
TR                  Technical Report
TrCH              Transport Channel
TS                  Technical Specification
TSG               Technical Specification Group
TSN               Transmission Sequence Number
TTA                Telecommunications Technology Association
TTC               Telecommunications Technology Committee
TTI                Transmission Time Interval
UCI               Uplink Control Information
UE                 User Equipment, the 3GPP name for the mobile terminal
UGS              Unsolicited Grant Service
UL                 Uplink
UL-SCH        Uplink Shared Channel
UM                Unacknowledged Mode (RLC configuration)
UMB             Ultra Mobile Broadband
UMTS           Universal Mobile Telecommunications System
UpPTS          The uplink part of the special subframe (for TDD operation).
USIM            UMTS SIM
US-TDMA    US Time Division Multiple Access standard
UTRA            Universal Terrestrial Radio Access
UTRAN         Universal Terrestrial Radio Access Network
VRB               Virtual Resource Block
WAN             Wide Area Network
WMAN         Wireless Metropolitan Area Network
WARC           World Administrative Radio Congress
WCDMA       Wideband Code Division Multiple Access
WG                Working Group
WiMAX         Worldwide Interoperability for Microwave Access
WLAN           Wireless Local Area Network
VoIP               Voice-over-IP
WP8F            Working Party 8F
WRC             World Radiocommunication Conference
X2                 The interface between eNodeBs.
ZC                 Zadoff-Chu
ZF                  Zero Forcing
ZTCC            Zero Tailed Convolutional Code

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Constellation diagram interpretation

The constellation diagram provides graphical representation of the complex envelope of each possible symbol state.

The X-axis of the diagram is called in-phase component and the y-axis represents the quadrature component.

 The distance between signals on constellation diagram relates to how different the modulation waveforms are and how well the receiver can differentiate between all possible symbols when random noise is present.
 
Some of properties of the modulation scheme can be inferred from the constellation diagram:

BW occupied by the modulation signals decreases as no. of points increases : i.e. if modulation scheme has a densely packed constellation it would be more bandwidth efficient.

Pe is proportional to the distance between the closest points in constellation : densely packed modulation scheme is less energy efficient than the modulation scheme that has sparse constellation

Comparison between constellation diagram interpretation on power and BW efficiencies. 

Probability of error and constellation diagram:
The constellation diagram can also be employed to find the upper bound for symbol error rate in AWGN channel with PSD=No
Is

And dij is Euclidean distance between ith and the jth points.

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Digital Modulation techniques

What Is The Modulation?

     Modulation is the process of encoding information from a message source in a manner suitable for transmission. 
It is generally involves translating a baseband message signal (called the source) to a bandpass signal at frequencies that are very high when compared to the base band frequency. 

The bandpass signal is called the modulated signal, and the baseband message signal is called the modulating signal. 

Modulation may be done by varying the amplitude, phase or frequency of a high frequency carrier in accordance with the amplitude of the message signal. 

Demodulation is the process of extracting the baseband message from the carrier so that it may be processed by the intended receiver.

Why we modulate signals?

• In order to ease propagation process and use an antenna of a suitable length. Since the effective radiation of EM waves requires antenna dimensions comparable with the wavelength:

        eg.  -Antenna for 3 kHz would be ~100 km long. 

               -Antenna for 3 GHz carrier is 10 cm long.

•  Sharing the access to the telecommunication channel resources:

       This is done by using FDM (Frequency division multiplexing) technique.

•  In order to transmit larger power for wide area:

         If we amplify the data power using power amplifiers, it will be distorted, so we perform modulation and amplify the carrier power.

•  In order to reduce noise effects in case of non-white Gaussian noise.

 Why Digital? (Analog versus Digital):

Modern mobile communication systems use digital modulation techniques.

Advancements in very large-scale integration (VLSI) and digital signal processing (DSP) technology have made digital modulation more cost effective than analog transmission systems.

Digital modulation offers many advantages over analog modulation.
Some advantages include greater noise immunity and robustness to channel impairments, easier multiplexing of various forms of information (e.g., voice, data, and video), and greater security.

Furthermore, digital transmissions accommodate digital error-control codes which detect and/or correct transmission errors, and support complex signal conditioning and processing techniques such as source coding, encryption, and equalization to improve the performance of the overall communication link.

New multipurpose programmable digital signal processors have made it possible to implement digital modulators and demodulators completely in software.

Instead of having a particular modem design permanently frozen as hardware, embedded software implementations now allow alterations and improvements without having to redesign or replace the modem. Table (1.1) shows a comparison between analog and digital modulation schemes to conclude the assessment of both modulation schemes usage in Wireless communication systems.

Table (1.1) comparisons between analog and digital modulation schemes

Factors that influence the choice of digital modulation:

A desirable modulation scheme should provide: Low bit error rates at low received signal to noise ratio.

•  Performs well in multi-path and fading conditions, and in interference environment.

•  Occupies a minimum bandwidth.

•  Easy and cost-effective to implement.

•  Cost and complexity of the receiver subscribers must be minimized.

•  Modulation which is simple to detect is most attractive.

Note That: There is no modulation scheme that satisfies all these requirements, so trade-offs are made when selecting a modulation scheme.

The performance of a modulation scheme:

The performance of the modulation scheme is measured by

•  Power efficiency (ηP).
•  Bandwidth efficiency(ηB).
•  Power spectral density.
•  System complexity.

 Power efficiency ηP:

The power efficiency is defined as the required Eb/No (Ratio of the signal energy per bit to noise power spectral density) at the input of the receiver for a certain bit error probability Pb over an AWGN channel
.
Power efficiency describes the ability of a modulation technique to preserve the bit error probability of digital message at low power levels.

In digital modulation systems, in order to increase the noise immunity, it is necessary to increase the signal power, so there is a trade-off between the signal power and the bit error probability.

The power efficiency is a measure of how favorably this trade-off is made.


Bandwidth efficiency (Spectral efficiency) ηB:

Bandwidth efficiency describes the ability of a modulation scheme to accommodate data within a limited bandwidth. As the data rate increases, pulse width of the digital symbols decreases and hence the bandwidth increases.

 The system capacity of a digital mobile communication system is directly related to the bandwidth efficiency for a modulation scheme.
So a modulation scheme with greater value of ηB will transmit more data in a given spectrum allocation.
Note that the maximum possible bandwidth efficiency is limited by the noise in the channel according to Shannon's Theorem as:

Where C is the channel capacity in bps , and S/N is the signal to noise ratio .

Bandwidth efficiency, Power efficiency Trade-off:

Adding error control coding to message increases the required bandwidth, then ηBdecreases, but the required received power for a particular bit error rate decreases and hence ηP increases.

On the other hand using high levels M'ary modulation schemes (except in M‘ary FSK modulation which isn‘t bandwidth limited modulation scheme), decreases the bandwidth occupancy, ηB increases, but the required received power for a particular bit error rate increases and hence ηP decreases.
 
System Complexity:

System complexity refers to the amount of circuits involved and the technical difficulty of the system.

Associated with the system complexity is the cost of manufacturing, which is of course a major concern in choosing a modulation technique.

Usually the demodulator is more complex than the modulator. Coherent demodulator is much more complex than no coherent demodulator since carrier recovery is required.

For some demodulation methods, sophisticated algorithms like the Viterbi algorithm are required. Also note that, for all personal communication systems which serve a large user community, the cost and complexity of the subscriber receiver must be minimized, and a modulation which is simple to detection is most attractive All these are basis for complexity comparison.

Since power efficiency, bandwidth efficiency, and system complexity are the main criteria of choosing a modulation technique, we will always pay attention to them in the analysis of modulation techniques.

Other considerations:

While power and bandwidth efficiency considerations are very important, other factors also affect the choice of a digital modulation scheme.

For example The performance of the modulation scheme under various types of channel impairments such as Rayleigh and Rician fading and multipath time dispersion, given a particular demodulator implementation, is another key factor in selecting a modulation.

 In cellular systems where interference is a major issue, the performance of a modulation scheme in an interference environment is extremely important.

Sensitivity to detection of timing jitter, caused by time-varying channels, is also an important consideration in choosing a particular modulation scheme.

In general, the modulation, interference, and implementation of the time varying effects of the channel as well as the performance of the specific demodulator are analyzed as a complete system using simulation to determine relative performance and ultimate selection.

Digital modulation techniques may be classified into coherent and non-coherent techniques depending on whether the receiver is equipped with a phase-recovery circuit or not.

The phase recovery circuit ensures that the oscillator supplying the locally generated carrier wave in the receiver is synchronized (in both frequency and phase) to the transmitter oscillator.

Fig.(1.1) Digital modulation according to demodulation type

The modulation schemes listed in the fig. (1.2) and the tree are classified into two large categories: constant envelope and non-constant envelope.

 Under constant envelope class, there are three subclasses: FSK and PSK. Under non constant envelope class, there are three subclasses: ASK and QAM.

Fig.(1.2) Digital modulation hierarchy

  

Types of modulation schemes in different advanced digital communication systems:

Table (1.2) shows examples of the used modulation schemes in different wireless modern communication systems

 

Table (1.2) Modulation schemes used in advanced communication systems

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Long Term Evolution (LTE)introduction

     Long Term Evolution (LTE) is a 4G wireless broadband technology developed by the Third Generation Partnership Project (3GPP), an industry trade group. 


     3GPP engineers named the technology "Long Term Evolution" because it represents the next step (4G) in a progression from GSM, a 2G standard, to UMTS, the 3G technologies based upon GSM. 

     LTE provides significantly increased peak data rates, with the potential for 100 Mbps downstream and 30 Mbps upstream, reduced latency, scalable bandwidth capacity, and backwards compatibility with existing GSM and UMTS technology, Future developments to could yield peak throughput on the order of 300 Mbps. 

     The upper layers of LTE are based upon TCP/IP, which will likely result in an all-IP network similar to the current state of wired communications.

     LTE will support mixed data, voice, video and messaging traffic.

     LTE uses OFDM (Orthogonal Frequency Division Multiplexing) and, in later releases, MIMO (Multiple Input Multiple Output) antenna technology similar to that used in the IEEE 802.11n wireless local area network (WLAN) standard. 

     The higher signal to noise ratio (SNR) at the receiver enabled by MIMO, along with OFDM, provides improved coverage and throughput, especially in dense urban areas.

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