Space Division Multiple Access (SDMA) is a communication method that allows multiple users to share a single channel by creating parallel spatial channels using advanced smart antenna technology, enhancing system capacity, speed, and quality. It operates in both uplink and downlink modes, focusing on user data to minimize interference. While SDMA improves transmission quality and is free from interference, it also involves high costs and complex construction.

1. SPACE DIVISION MULTIPLE
ACCESS (SDMA)
Soumen Santra

2. Multiple Access
Provide communication service to multiple users.
 Use a single channel.
 It allows for many users at one time by sharing finite
amount of spectrum.

3. It is a channel access method based on creating parallel
spatial channels.
 It uses advanced antenna technology.
 It uses of smart antenna array systems at the base
station.
It exploit spatial diversity.
The communication channel encountered by this array of
antennas.
SDMA : Definition

4. Smart Antenna
A Smart Antenna is an antenna array.
It dynamically adapts its radiation pattern.
It improve system performance.
The overall radiation pattern is determined by the
relative amplitude and phase of the excitation currents.

5. SDMA ?
To increase system capacity, speed and quality.
 To increasing demand for wireless services.
 It increases system capacity.
It can be exploited Spatial diversity in both Uplink
and Downlink.
 Uplink (Mobile User transmitting to Base Station)
 Downlink (Base Station transmitting to Mobile User).

6. Uplink

7. Uplink Transmission
 The smart antenna array is operating in a passive mode.
Electromagnetic signals induce currents on the array
elements from mobile users .

8. Downlink

9. Downlink Transmission
Working upon two mobile users.
Smart antenna is operating in an active mode.
It uses focus mobile user data as an appropriate user.
A null is placing in the radiation pattern of the other
mobile user.
Interference signal of one mobile user to be minimized.

10. SDMA : Block Diagram

11. SDMA : Features
 Spatial separation between multiple transmissions.
 Multiple-Input Multiple Output architecture.
 Set of users in wireless mode communicate with each
other by antennas.
 Used in Wireless, Satellite and Optical Communication.
 Controls the radiated energy in space.
 Stations communicate at the same time using the same
channel.

12. SDMA : Features
 The same set of cell phone frequencies in a given service
area.
 Allocating a separated space to users in wireless network.
 Smart antennas with beams pointed at the direction of the
mobile station.
 It serves with different users within the same region.
 One satellite can communicate with other’s receivers by
same frequency.
 The directional spot-beam antennas of base station can
track a moving user.
 Combination work with FDMA or TDMA or CDMA.

13. SDMA : Beam Frequency Reuse
It is also called as Multiple Beam Frequency Reuse.
It reuses the same set of cell phone frequencies in a given
service area.
Two cells or two small regions can make use of same set of
frequencies if they separated by an allowable distance which
is called the reuse distance.

14. SDMA : Advantages
 Increases the capacity and speed of the system.
 Increases transmission quality by focusing the
signal into narrow transmission beams.
 Free from interference.
 All users can communicate at the same time
using the same channel.
 Two different signals can use the same
frequency.
 The narrow beam width also allows greater
gain and clarity.
 It minimizes system cost.

15. SDMA : Disadvantages
High insertion losses because input must have the
capability to be split into any output.
 Very expensive.
 Complicated to construct and design.

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