CDMA systems use code division multiple access (CDMA) to allow multiple users to access the network simultaneously using the same frequency band. CDMA uses spreading codes to distinguish between users, allowing signals to overlap in both time and frequency. Key aspects of CDMA include soft handoff which provides better call quality during handoffs, rake receivers which mitigate multipath interference, and intelligent vocoders which provide high quality voice compression. CDMA networks also use power control and simple network planning to provide better coverage than comparable systems while using less infrastructure. The cdma2000 1x standard provided increased data speeds and backward compatibility with earlier CDMA networks.
There are several possible methods for increasing
transmission capacity over fixed bandwidth.
These include modulation employing different amplitude
levels, two orthogonal subcarriers and polarization.
In fact, the only remaining unused dimension is Space.
Orthogonal Frequency Division Multiplexing, OFDM uses a large number of narrow sub-carriers for multi-carrier transmission to overcome the effect of multi path fading problem. LTE uses OFDM for the downlink, from base station to terminal to transmit the data over many narrow band careers of 180 KHz each instead of spreading one signal over the complete 5MHz career bandwidth. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates.
The primary advantage of OFDM over single-carrier schemes is its ability to cope with severe channel conditions. Channel equalization is simplified. The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate inter symbol interference (ISI).
SPACE DIVISION MULTIPLE ACCESS (SDMA) SATELLITE COMMUNICATION Soumen Santra
SPACE DIVISION MULTIPLE ACCESS (SDMA)
Definition : The communication channel encountered by this array of antennas.
advanced antenna technology.
Smart Antenna
Uplink Transmission
Downlink Transmission
Block Diagram
Features
Beam Frequency Reuse
Advantages
Disadvantages
There are several possible methods for increasing
transmission capacity over fixed bandwidth.
These include modulation employing different amplitude
levels, two orthogonal subcarriers and polarization.
In fact, the only remaining unused dimension is Space.
Orthogonal Frequency Division Multiplexing, OFDM uses a large number of narrow sub-carriers for multi-carrier transmission to overcome the effect of multi path fading problem. LTE uses OFDM for the downlink, from base station to terminal to transmit the data over many narrow band careers of 180 KHz each instead of spreading one signal over the complete 5MHz career bandwidth. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates.
The primary advantage of OFDM over single-carrier schemes is its ability to cope with severe channel conditions. Channel equalization is simplified. The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate inter symbol interference (ISI).
SPACE DIVISION MULTIPLE ACCESS (SDMA) SATELLITE COMMUNICATION Soumen Santra
SPACE DIVISION MULTIPLE ACCESS (SDMA)
Definition : The communication channel encountered by this array of antennas.
advanced antenna technology.
Smart Antenna
Uplink Transmission
Downlink Transmission
Block Diagram
Features
Beam Frequency Reuse
Advantages
Disadvantages
Basic Telecom concepts
Various Wireless Technologies
Cellular concepts & Principal of cellular Comm.
GSM Network Architecture
GSM channel Architecture
Call Flows in GSM
GSM Planning steps (Nominal Plan & RF surveys)
Alternative means of wireless communication
Walkie - Talkie
Pagers
Trunked private radios
Mobile Phone - the magic technology that enables everyone to communicate anywhere with anybody.
Till 1982 Cellular Systems were exclusively Analog Radio Technology.
Advanced Mobile Phone Service (AMPS)
U.S. standard on the 800 MHz Band
Total Access Communication System (TACS)
U.K. standard on 900 MHz band
Nordic Mobile Telephone System (NMT)
Scandinavian standard on the 450 & 900 MHz band
Basic Telecom concepts
Various Wireless Technologies
Cellular concepts & Principal of cellular Comm.
GSM Network Architecture
GSM channel Architecture
Call Flows in GSM
GSM Planning steps (Nominal Plan & RF surveys)
Alternative means of wireless communication
Walkie - Talkie
Pagers
Trunked private radios
Mobile Phone - the magic technology that enables everyone to communicate anywhere with anybody.
Till 1982 Cellular Systems were exclusively Analog Radio Technology.
Advanced Mobile Phone Service (AMPS)
U.S. standard on the 800 MHz Band
Total Access Communication System (TACS)
U.K. standard on 900 MHz band
Nordic Mobile Telephone System (NMT)
Scandinavian standard on the 450 & 900 MHz band
1: Direct sequence and frequency hopped spread spectrum, spreading sequence and their correlation functions, Acquisition and tracking of spread spectrum signals.
2: Error probability for DS-CDMA, on AWGN channels, DS-CDMA on frequency selective fading, channels, Performance analysis of cellular CDMA.
3: Capacity estimation, Power control, effect of imperfect power control on DS CDMA performance, Soft Handoffs.
4: Spreading /coding tradeoffs, multi-carrier CDMA, IS-95 CDMA system, third generation CDMA systems, multi-user detection.
you can be friend with me on orkut
"mangalforyou@gmail.com" : i belive in sharing the knowledge so please send project reports ,seminar and ppt. to me .
In CDMA , All user share the same radio channel.If one user take more power than it need, then other will be suffer and capacity will be decreased.
This presentation adresses how to tune The CDMA cellular radio network in order to tolarate interference.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
2. Contents
The characteristics of mobile
communications
CDMA migration from 2G to 3G
CDMA spectrum usage
CDMA Codes
CDMA Channels
The advantage of CDMA
cdma2000 -1x
3. Characteristics of Mobile
Communication
• Mobility:
– flexible and convenient , global personal
communication
• Poor environment and conditions :
– Co-channel interference, multi-path(space and
time)shadow effect and delay, power change and
other noise
• Multiple MS and channels:
– Interference, near and far effect
• Limit of frequency resources
• Reliability is important
– registration, handoff, switching
4. Communications System
AMPS: Advanced Mobile Phone System
TACS: Total Access Communication System
GPRS: General Packet Radio Services
11GG 22GG 33GG
Analog
cellular
DDiiggiittaall cceelllluullaarr DDiiggiittaall cceelllluullaarr
VVooiiccee VVooiiccee //ddaattaa VViiooccee // hhiigghh ssppeeeedd ddaattaa
AAMMPPSS CCDDMMAA 11XXRRtttt CCDDMMAA22000000
TTAACCSS GGSSMM GGPPRRSS WW__CCDDMMAA
8800’’ 11999922 11999999 22000011 22000033
7. CDMA-Its History & Status
1993, the first CDMA standard IS-95 was issued;
In 1995, CDMA technology was put into
commercialization in Hong Kong and America on
large scale;
In April, 2001, China Unicom began to construct
CDMA networks—the largest in the world (about
70Million line now);
At present, CDMA commercial networks are
established in about 40 countries or area, almost
20% of all users in the world.
9. CDMA 800 MHz Cellular
Spectrum Usage
Possible CDMA
Center Freq. Assignments
Channel
Numbers
Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)824
MHz
849
MHz
869
MHz
894
MHz
other
usesA” A”A B A’ B’
1 10 10 1.5 2.5
A B A’ B’
1 10 10 1.5 2.5
991
1023
1
333
334
666
667
716
717
799
991
1023
1
333
334
666
667
716
717
799
~300 kHz. “guard bands” possibly required if adjacent-
frequency signals are non-CDMA (AMPS, TDMA, ESMR, etc.)
• All CDMA RF carriers are 1.25 MHz. wide
– Can serve ~20 users /8 kb vocoder
10. CDMA PCS 1900 MHz
Spectrum Usage
Guard Bands
Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)
1850
MHz
B
T
A
B
T
A
B
T
A
B
T
A
B
T
A
B
T
A
Paired Bands
MTA BTAMTABTA MTAMTA
1910
MHz
1930
MHz
1990
MHz
Data Voice
A D B E F C A D B E F C
15 51010 1515151515 555 55
Licensed Licensed
Unlicensed
0
Channel
Numbers
299
300
400
699
700
800
900
1199
0
299
300
400
699
700
800
900
1199
11. CDMA Frequency Channel
Assignment at 800 MHz Cellular
1
334
667
991
1023
333
666
715
799
716
Channel
Numbers
A Band B Band A’A” B’
1019 37 78 119 160 201 242 283 384 425 466 507 548 589 630 691 777
CDMA A-Band Carriers CDMA B-Band Carriers
8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 9 9 8
* ***
* Requires frequency
coordination with non-cellular
interferers
** Requires frequency
coordination with A-band
carrier
A Band Primary Channel 283
A Band Secondary Channel 691
B Band Primary Channel 384
B Band Secondary Channel 777
736
12. Multiple Access
Each pair of users
enjoys a dedicated,
private circuit through
the transmission
medium, unaware that
the other users exist.
Since the beginning of telephony and radio,
system operators have tried to squeeze the
maximum amount of traffic over each circuit. Transmission
Medium• Types of Media -- Examples:
– Twisted pair - copper
– Coaxial cable
– Fiber optic cable
– Air interface (radio signals)
Advantages of Multiple Access
–Increased capacity: serve more users
–Reduced capital requirements since fewer
media can carry the traffic
–Decreased per-user expense
–Easier to manage and administer
13. Multiple Access Schemes
Power
Power
Power
FDMA
TDMA
CDMA
• FDMA Frequency Division Multiple
Access
– Each user on a different frequency
– A channel is a frequency
• TDMA Time Division Multiple Access
– Each user on a different window
period in time (“time slot”)
– A channel is a specific time slot on a
specific frequency
• CDMA Code Division Multiple Access
– A channel is a unique code pattern
– Each user uses the same frequency
all the time, but mixed with
different distinguishing code
patterns
15. Terms & Definitions
• CDMA Channel or CDMA Carrier or CDMA Frequency
– Duplex channel made of two 1.25 MHz-wide bands of electromagnetic
spectrum, one for Base Station to Mobile Station communication (called the
FORWARD LINK or the DOWNLINK) and another for Mobile Station to Base
Station communication (called the REVERSE LINK or the UPLINK)
– In 800 Cellular these two simplex 1.25 MHz bands are 45 MHz apart
– In 1900 MHz PCS they are 80 MHz apart
• CDMA Forward & Reverse Channel
– 1.25 MHz Forward / Reverse Link
• CDMA Code Channel
– Each individual stream of 0’s and 1’s contained in either the CDMA Forward
Channel or in the CDMA Reverse Channel
– Code Channels are characterized (made unique) by mathematical codes
– Code channels in the forward link: Pilot, Sync, Paging and Forward Traffic
channels
– Code channels in the reverse link: Access and Reverse Traffic channels
45 or 80 MHz
CDMA CHANNEL
CDMA
Reverse
Channel
1.25 MHz
CDMA
Forward
Channel
1.25 MHz
16. Walsh Codes
• 64 Sequences, each 64 chips long
– A chip is a binary digit (0 or 1)
• Each Walsh Code is Orthogonal to all other Walsh
Codes
– This means that it is possible to recognize and
therefore extract a particular Walsh code from a
mixture of other Walsh codes which are “filtered
out” in the process
– Two same-length binary strings are orthogonal if
the result of XORing them has the same number
of 0s as 1s
17. Short PN Sequences
• The two Short PN Sequences, I and Q, are 32,768
chips long
• Together, they can be considered a two-dimensional
binary “vector” with distinct I and Q component
sequences, each 32,768 chips long
• Each Short PN Sequence (and, as a matter of fact, any
sequence) correlates with itself perfectly if compared
at a timing offset of 0 chips
• Each Short PN Sequence is special: Orthogonal to a
copy of itself that has been offset by any number of
chips (other than 0)
18. The Long PN Sequence
• Each mobile station uses a unique User Long Code Sequence
generated by applying a mask, based on its 32-bit ESN, to the
42-bit Long Code Generator which was synchronized with
the CDMA system during the mobile station initialization.
• Generated at 1.2288 Mcps, this sequence requires 41 days, 10
hours, 12 minutes and 19.4 seconds to complete.
Long Code Register
(@ 1.2288 MCPS)
Public Long Code Mask
(STATIC)
User Long Code
Sequence
(@1.2288 MCPS)
1 1 0 0 0 1 1 0 0 0 P E RMU T E D E S N
AND
=S UM
Modulo-2 Addition
19. Coding Process on CDMA
Forward Channels
WALSH
19
BTSPilot Walsh 0
Walsh 19
Paging Walsh 1
Walsh 6
Walsh 11
Walsh 20
Sync Walsh 32
Walsh 42
Walsh 37
Walsh 41
Walsh 56
Walsh 60
Walsh 55
PN OFFSET 116BTS
PN OFFSET 226BTS
PN OFFSET 510BTS
S
PN
372
x
x
x
PN OFFSET
ANALOG
SUM/MUX
PN OFFSET 372
20. CDMA Code Summary
Walsh Codes
Short PN
Sequences
Long PN
Sequences
Type of
Sequence
Mutually
Orthogonal
Orthogonal with
itself at any time
shift value
except 0
near-orthogonal
if shifted
Special
Properties
64
2
1
How
Many
64 chips
1/19,200 sec.
32,768 chips
26-2/3 ms
75x in 2 sec.
242 chips
~41 days
Length
Orthogonal
Modulation
(information carrier)
Quadrature
Spreading
(Zero offset)
Distinguish users
Reverse Link
Function
User identity
within cell’s
signal
Distinguish Cells
& Sectors
Data Scrambling
to avoid strings
of 1’s or 0’s
Forward Link
Function
21. CDMA Advantages
• Spread Spectrum
• Soft & Softer Handoff
• Rake Receiver
• Variable Rate Vocoder
• High quality voice
• Power Control
• Coverage
• Simple Network Planning
• Green Handset
• Smooth migration to 3G and the operator’s
benefit is protected at the most
22. Spread Spectrum (1)
S(f)
ff0
Before spreading
Signal
S(f)
ff0
After spreading
Signal
S(f)
ff0
After despreading
signal
Interfering noise
f
S(f)
f0
Before despreading
Signal
Interfering noise
24. Spreading Spectrum (3)
“Principle of Using Multiple Codes”
Spreading
Sequence
A
Spreading
Sequence
B
Spreading
Sequence
C
Spreading
Sequence
C
Spreading
Sequence
B
Spreading
Sequence
A
Input
Data
X
Recovered
Data
X
X+A X+A+B X+A+B+C X+A+B X+A
Spread-Spectrum Chip Streams
ORIGINATING SITE DESTINATION
26. Advantages of Spread
Spectrum
Avoid interference arising from jamming
signal or multi-path effects.
Covert operation:Difficult to detect
Achieve Privacy: Difficult to demodulate,
Noise like signal.
Impossible to Eavesdrops on the signal
expect using the same PN sequence
27. Soft & Softer Handoff
Connection first and disconnection
afterwards in handoff.
High quality of service and effective
reduction of call drops.
Softer handoff: same BS &
frequency, between different sectors.
Soft handoff: adjacent cells of
the same frequency.
BSC
BSC MSC
30. Rake Receiver (3)
• Handset uses combined outputs of the three traffic
correlators ―rake fingers‖
• Each finger can independently recover a particular
PN offset and Walsh code
• Fingers can targeted on delayed multipath
reflections, or even on different BTSs
• Searcher continuously checks pilots
34. Power Control
Autonomous power control
On the Uplink tells the MS to vary it’s transmitted power inversely with
the power level it receive from the BS.
Direct power control
On the Uplink measures Eb/No at the base station and sends power
Control Bits over the Downlink to the MS to instruct the MS to
either increase or decrease its transmit power.
Downlink power control
Attempts to use minimum power needed to meet to a Frame Error Rate
(FER) threshold at the MS s.
35. Coverage
• The coverage radius is 2 times of
standard GSM.
• Coverage of 1000 km2: GSM
needs 200 BTS 's, while CDMA
requires only 50.
• Under the same coverage
conditions, the number of BTS 's
is greatly decreased
38. Functions of the CDMA
Reverse Channels
• There are two types of CDMA Reverse
Channels:
– TRAFFIC CHANNELS are used by
individual
users during their actual calls to transmit
traffic
to the BTS.
– ACCESS CHANNELS are used by mobile
stations not yet in a call to transmit
registration requests, call setup requests, page
responses, order responses, and other
signaling information
39. Coding Process on CDMA
Reverse Channels
• Each mobile is uniquely identified by the User Long
Code, which it generates internally.
• All mobile stations transmit simultaneously on the
same 1.25 MHz wide frequency band.
• Any nearby BTS can dedicate a channel element to
the mobile station and successfully extract its signal.
• Mobile stations also use the other CDMA spreading
sequences, but not for channel-identifying purposes.
• Short PN Sequences are used to achieve phase
modulation.
• Walsh Codes are used as Orthogonal Modulation to
give ultra-reliable communications recovery at the
BTS.
40. Benefits of the cdma2000 1x
Standards
• Increased mobile standby battery life (via Quick
Paging Channel)
• Total backward compatibility to reuse switch
and call processing features
• 2-3 dB better coverage
• High speed 153.6 kbps packet data capabilities
• cdma2000 1x = 1.25 MHz Radio Transmission
Technology
41. Backward Compatible with
IS-95 Air Interface
IS-95 mobiles are supported in the IS-
2000 standard for 1xRTT:
• No need to change any RF infrastructure
• Capacity improvements will not be
realized until most IS-95 subscribers
disappear
42. Channel List: 1xRTT vs. IS-95
• IS-95B built on the IS-95A channels, and introduced two new channels
– Fundamental channel was the same as IS-9A traffic channel
– Supplemental code channels assigned to support rates above 14.4Kbps
• IS-2000 1xRTT continue to build on the IS-95 channels
– IS-95 channels continue to be supported in IS-2000 to support IS-95
mobiles
Pilot channel
Sync channel
Paging channel Access channel
Forward Traffic Channel Reverse Traffic Channel
Fundamental channel Fundamental channel
Supplemental Code channel (F-SCCH) Supplemental Code channel (R-SCCH)
Supplemental channel (F-SCH) Supplemental channel (R-SCH)
Quick Paging channel (F-QPCH) Reverse Pilot channel (R-PICH)
IS-95B
1xRTT
IS-95A
Forward Reverse
43. Discriminating Among Forward
Code Channels
• A Mobile Station receives a Forward Channel from a sector
in a Base Station.
• The Forward Channel carries a composite signal of up to 64
forward code channels.
• Some code channels are traffic channels and others are
overhead channels.
• A set of 64 mathematical codes is needed to differentiate the
64 possible forward code channels.
– The codes in this set are called “Walsh Codes”
SyncPilot
FW Traffic
(for user #1)
Paging
FW Traffic
(for user #2)
FW Traffic
(for user #3)
44. Discriminating Among Base
Station
• A mobile Station is surrounded by Base Stations, all of them transmitting on
the same CDMA Frequency.
• Each Sector in each Base Station is transmitting a Forward Traffic Channel
containing up to 64 forward code channels.
• A Mobile Station must be able to discriminate between different Sectors of
different Base Stations.
• Two binary digit sequences called the I and Q Short PN Sequences (or Short
PN Codes) are defined for the purpose of identifying sectors of different
base stations.
• These Short PN Sequences can be used in 512 different ways in a CDMA
system. Each one of them constitutes a mathematical code which can be
used to identify a particular sector.
A B
Up to 64
Code Channels
Up to 64
Code Channels