Channel Access Method; Carrier-Sense Multiple Access With Collision Avoidance (Csma/Ca); Time-Division Multiple Access (Tdma) - TRENDnet TEW-840APBO User Manual

TRENDnet User's Guide

Channel Access Method

In wireless networking, Channel Access Method, or Multiple Access Method, refers to
the method used to enable simultaneous isolated communications between multiple
devices all sharing the same "communication medium" of wireless radio airspace.
TRENDnet's TEW-840APBO and TEW-840APBO2K support two methods of channel
access: Carrier-Sense Multiple Access with Collision Avoidance (CSMA/CA, shortened
to just CSMA) and Time-Division Multiple Access (TDMA).
The different methods can be found under Network > Wireless > Channel Access Mode
in the access point web management page.
Carrier-Sense Multiple Access with Collision Avoidance
(CSMA/CA)
CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) is the standard
access mode used in 802.11 networks and is used for both access points and client
device/station connectivity.
Due to allowing connections without any beacon packets and synchronization, CSMA/CA
is better suited for environments with several networks in parallel.
Consequently, due to an increase in interference and energy consumption, CSMA/CA
causes higher collision rates and decreases network throughput in a dense network
when compared with TDMA. Retransmissions resulting from collisions are another factor
in terms of network throughput and energy consumption.

Industry standard.

Simple, distributed, burden-less channel access method.

Allows for fair sharing of network resources between contending nodes, at the
cost of optimal quality of service and a guaranteed balance – especially when
quantity of contending nodes increases.

Example: IEEE 802.11 WiFi
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Time-Division Multiple Access (TDMA)

TDMA (Time Division Multiple Access) is a proprietary access method that can
provide significant benefits in performance and capacity in 802.11 point-to-point
and point-to-multipoint bridge applications between wireless access points.
Through the use of dynamic time slot allocation to client/station access points,
TDMA can eliminate data collisions and manage airtime more efficiently for active
and inactive client/station access points when compared to the conventional CSMA.
Consequently, due to the very precise duty cycling requiring each sensor to wait
their respective turn before communicating, TDMA has an increased
communication delay when the network traffic is low when compared to CSMA/CA.
Additionally, TDMA is unable to avoid inter-network interference as well as CSMA is.

Proprietary

Centralized, scheduled, managed, planned channel access method.

Guarantees your target quality of service and balanced network shares
among all your nodes, at the cost of inter-network interference from other
networks running in parallel.

Example: TEW-840APBO2K
TEW-840APBO / TEW-840APBO2K
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