Cordless systems can operate in residential, office, and public environments like airports. Cordless standards consider modest handset range, inexpensive devices, and frequency flexibility. Time Division Duplex (TDD) transmits data in one direction at a time, alternating between the two directions. With Simple TDD, the bit stream is divided and transmitted in bursts with guard time. TDMA TDD allows multiple users by assigning time slots. The Digital Enhanced Cordless Telecommunications (DECT) frame format includes fields for preamble, synchronization, network control data, user data, and guard time. DECT uses TDD and supports broadcast, connection-oriented, and connectionless services across its physical and data link control layers.
This presentation based on TDMA technology,How it works,comparison between TDMA,FDMA,CDMA,Advantages and disadvantages of TDMA,Synchronization of TDMA and Evolution of TDMA
Overview
WLAN Technologies - Infrared LANs, Spread Spectrum LANs, Narrowband Microwave LANs
IEEE 802.11 – Architecture, protocols, MAC layer, MAC Frame, MAC Management
Infra Red
Orbits : types of satellites : frequency used link establishment, MA techniques used in satellite communication, earth station; aperture actuators used in satellite – Intelsat and Insat: fibers – types:
sources, detectors used, digital filters, optical link: power line carrier communications: SCADA
Hai I'm Senthilkanth, doing MCA in Mepco Schlenk Engineering College..
The following presentation covers topic called WML for BSc CS, BCA, MSc CS, MCA, ME students.Make use of it. WML Script by Shanti katta.
This presentation agenda like,
This presentation based on TDMA technology,How it works,comparison between TDMA,FDMA,CDMA,Advantages and disadvantages of TDMA,Synchronization of TDMA and Evolution of TDMA
Overview
WLAN Technologies - Infrared LANs, Spread Spectrum LANs, Narrowband Microwave LANs
IEEE 802.11 – Architecture, protocols, MAC layer, MAC Frame, MAC Management
Infra Red
Orbits : types of satellites : frequency used link establishment, MA techniques used in satellite communication, earth station; aperture actuators used in satellite – Intelsat and Insat: fibers – types:
sources, detectors used, digital filters, optical link: power line carrier communications: SCADA
Hai I'm Senthilkanth, doing MCA in Mepco Schlenk Engineering College..
The following presentation covers topic called WML for BSc CS, BCA, MSc CS, MCA, ME students.Make use of it. WML Script by Shanti katta.
This presentation agenda like,
A frequently used class of objects are the quadric surfaces, which are described with second-degree equations (quadratics). They include spheres, ellipsoids, tori, paraboloids, and hyperboloids.
Quadric surfaces, particularly spheres and ellipsoids, are common elements of graphics scenes
A complete power point presentation to know how Public Switching Telephone Network works. Useful for those in the working field or for the ones who want to know more or submitting any project report..
2. Cordless System Operating Environments
Residential – a single base station can
provide in-house voice and data support
Office
A single base station can support a small office
Multiple base stations in a cellular
configuration can support a larger office
Telepoint – a base station set up in a public
place, such as an airport
3. Design Considerations for Cordless Standards
Modest range of handset from base station,
so low-power designs are used
Inexpensive handset and base station,
dictating simple technical approaches
Frequency flexibility is limited, so the
system needs to be able to seek a low-
interference channel whenever used
4. Time Division Duplex (TDD)
TDD also known as time-compression
multiplexing (TCM)
Data transmitted in one direction at a time,
with transmission between the two
directions
Simple TDD
TDMA TDD
5. Simple TDD
Bit stream is divided into equal segments,
compressed in time to a higher transmission rate,
and transmitted in bursts
Effective bits transmitted per second:
R = B/2(Tp+Tb+Tg)
R = effective data rate
B = size of block in bits
Tp = propagation delay
Tb = burst transmission time
Tg = guard time
6. Simple TDD
Actual data rate, A:
A = B /Tb
Combined with previous equation:
The actual data rate is more than double the
effective data rate seen by the two sides
+
+=
b
gp
T
TT
RA 12
7. TDMA TDD
Wireless TDD typically used with TDMA
A number of users receive forward channel
signals in turn and then transmit reverse
channel signals in turn, all on same carrier
frequency
Advantages of TDMA/TDD:
Improved ability to cope with fast fading
Improved capacity allocation
8. DECT Frame Format
Preamble (16 bits) – alert receiver
Sync (16 bits) – enable receiver to
synchronize on beginning of time slot
A field (64 bits) – used for network control
B field (320 bits) – contains user data
X field (4 bits) – parity check bits
Guard (60 bits) – guard time, Tg
9. A Field Logical Control Channels
Q channel – used to broadcast general system
information from base station to all terminals
P channel – provides paging from the base station
to terminals
M channel – used by terminal to exchange
medium access control messages with base station
N channel – provides handshaking protocol
C channel – provides call management for active
connections
10. B Field
B field transmits data in two modes
Unprotected mode - used to transmit digitized
voice
Protected mode - transmits nonvoice data traffic
12. DECT Protocol Architecture
Physical layer – data transmitted in TDMA-TDD
frames over one of 10 RF carriers
Medium access control (MAC) layer – selects/
establishes/releases connections on physical
channels; supports three services:
Broadcast
Connection oriented
Connectionless
Data link control layer – provides for the reliable
transmission of messages using traditional data
link control procedures