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Wireless Communications Solutions

Universal Mobile Telecommunication System (UMTS)

Overview  |  Reverse/Forward Process  |  Library Components

 

    3G/UMTS - Overview

Referred to as the third generation (3G) cellular communication system, UMTS promises to provide high speed data access at up to 2 Mbps. Nuntius has solutions for UMTS phone developers in Layer 1 and Layer 2 functions of both FDD and TDD modes. Below is a list of some of the characteristics of UMTS. For more information contact Nuntius Systems, Inc.

Standard:
Wideband Code Division Multiple Access (W-CDMA)
Time Division Code Division Multiple Access (TDCDMA)
Speech:
High quality speech using low bit rates
Data rates:
Macro cell   -   144 kbps in rural with max. speed of 500 km/h
Micro cell    -   384 kbps in suburban with max. speed of 120 km/h
Pico cell     -   2Mbps with max. speed of 10 km/h
Channel coding
Forward error correction coding
Convolutional coding (rate 1/2 or 1/3) with block interleaving
Optional outer Reed-Solomon Coding (rate 4/5)
Service specific coding - Turbo coding
Modulation
Quadrature Phase Shift Keying (QPSK) with
Root-raised cosine pulse shaping filters (roll off = 0.22)
Multiple Access
Direct Sequence CDMA
        Orthogonal Variable Rate Spreading Factor Codes (OVSF)
                Spreading factors from 4 - 256 to match different user bit rates

Frequency bands
Uplink
Downlink
Carrier spacing
Chip rate
Information bandwidth    
1920 - 1980 MHz
2110 - 2170 MHz
4.4 - 5.2 MHz
3.84 Mchips/s
8 kbps - 2 Mbps

Duplex - FDD/TDD
Frame Interval     10 ms
 
Time slots per frame     16

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    3G/UMTS - Reverse / Forward Link

Transmitter power:     -    30 dbm (max)

Data rate:
8 kbps to 2 Mbps
Channel codes
Convolutional inner code (1/2 or 1/3)
Optional outer Reed-Solomon code (4/5)
Service specific coding such as Turbo code
Unequal repetition and / or puncturing for rate matching
Interleaving
Inner: Block interleaving with variable block size (10 - 150 ms)
Outer: Block interleaving with variable block size (10 - 150 ms)
Channelization codes
Orthogonal Variable Spreading Factor code (OVSF)
 
Scrambling codes (reverse link)
Primary code         -     256 chip Kasami code
Secondary code    -     Segment of long Gold code
Scrambling codes (forward link)
Segment of long Gold code
Short Orthogonal codes on Physical and Synchronization channels
Modulation (forward link)
Data             -     QPSK

Spreading    -     QPSK


Channels
Common Pilot channel

       Primary common control Physical channel (P-CCPCH)

             Synchronization channel (SCH)

       Secondary common control Physical channel (S-CCPCH)

Paging information
       Physical downlink shared channel (PDSCH)

       Page indication channel (PICH)

       Acquisition indication channel (AICH)

       Dedicated Physical Data Channel (DPDCH)

       Dedicated Physical Control Channel (DPCCH)

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    3G/UMTS - Standard Library Functions

The following is a list of the standard library functions to perform the various aspects of UMTS. Although these functions can be implemented in a DSP or the ARM RISC architecture, due to the high chip rates, it may be necessary to implement some functions in an FPGA or ASIC. However, there are some high MIPS and low power chips coming out into the market that may allow all the layer 1 functions to be implemented in software. The advantage to this is the possibility of mulitprotocol stacks that include layer 1 tasks allowing a mobile to operate in multiple modes with simpler hardware designs.

Speech codec
Adaptive Multirate (AMR) voice codec     -     4.75 to 14 kbps
Channel codes
Forward Error Correction (FEC) coder
Cyclic Redundancy Check (CRC) coder
Convolutional inner coder (rate 1/2 or 1/3 with K=9)
Reed-Solomon outer coder
Service specific Turbo coder
Unequal repetition coder
Puncturing coder
Interleaver
Inner block interleaving
Outer block interleaving
PN codes
Orthogonal Variable Spreading Factor (4 to 256) generator
Short code generator (complex code from two 256 chip Kasami codes)
Long code generator (segment of Gold code)
Channel models
Multipath propogation (1-ray, 2-ray, 3-ray)
Modulation / Demodulation
QPSK
BPSK
RAKE Receiver

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