With the arrival of the new technologies,
applications and services in the field of networking, the competition is rising
rapidly. Each of these technologies, services and applications are developed
with an aim of delivering QoS (quality of service) that is either better with
the legacy equipment or better than that. The network operators and the service
providers follow from trusted brands. Maintenance of these brands is of
critical importance to the business of these providers and operators. The
biggest challenge here is to put the technology to work in such a way that all
the expectations of the customers for the availability, reliability and quality
are met and at the same time the flexibility for quick adaptation of the new
techniques is offered to the network operators.
What is Quality of Service?
- The quality of service is
defined by its certain parameters which play a key role in the acceptance of
the new technologies.
- The organization working on several specifications of QoS
is ETSI.
- The organization has been actively participating in the organization
of the inter-operability events regarding the speech quality.
- The importance of
the QoS parameters has been increasing ever since the increasing
inter-connectivity of the networks and interaction between many service
providers and network operators for delivering communication services.
- It is
the quality of service that grants you the ability for the making parameters
specifications based up on multiple queues in order to shoot up the performance
as well as the throughput of wireless traffic as in VoIP (voice over internet),
streaming media including audio and video of different types.
- This is also done
for usual IP over the access points.
- Configuration of the quality of service on
these access points involves setting many parameters on the queues that are
already there for various types of wireless traffic.
- The minimum as well as the
maximum wait times are also specified for the transmission.
- This is done
through the contention windows.
- The flow of the traffic between the access
point and the client station is affected by the EDCA (AP enhanced distributed
channel access) parameters.
- The traffic flow from client to the access point is
controlled by the station enhanced distribution channel access parameters.
Below
we mention some parameters:
Ø QoS
preset: The options listed by the QoS are WFA defaults, optimized for voice,
custom and WFA defaults.
Ø Queue: For different types of data transmissions between AP – to – client station,
different queues are defined:
- Voice (data 0): Queue with minimum delay and high
priority. Data which is time sensitive such as the streaming media and the VoIP
are automatically put in this queue.
- Video (data 1): Queue with minimum delay and high
priority. Video data which is time sensitive is put in to this queue
automatically.
- Best effort (data 2): Queue with medium delay and
throughput and medium priority. This queue holds all the traditional IP data.
- Background (data 3): Queue with high throughput and
lowest priority. Data which is bulky, requires high throughput and is not time sensitive such as the FTP data is queued up here.
Ø AIFS
(inter-frame space): This puts a limit on the waiting time of the data
frames. The measurement of this time is taken in terms of the slots. The valid
values lie in the range of 1 to 255.
Ø Minimum
contention window (cwMin): This QoS parameter is supplied as input to the
algorithm for determining the random back off wait time for re-transmission.
Ø cwMax
Ø maximum
burst
Ø wi – fi
multimedia
Ø TXOP
limit
Ø Bandwidth
Ø Variation
in delay
Ø Synchronization
Ø Cell
error ratio
Ø Cell loss
ratio
