QoS vs GoS Description Parameters and how they differ

1. i
QUALITY OF SERVICE AND GRADE OF SERVICE
DESCRIPTION, PARAMETERS AND HOW THEY DIFFER.
BY
DONAIRE CARAPICHOSO
AND
PAULO VANGUI

2. ii
Introduction
As the number of Internet users continues to grow, network performance requirements must increase
right along with them. In addition, many of the latest online services require high amounts of
bandwidth and network performance. Network performance is an element of concern both for the
user and the service provider. Internet service providers need to apply techniques and technologies
to provide the best service possible before their competitors beat them to it.
In this research we are going to discuss about some of these techniques and technologies, i.e. Quality
of Service and Grade of Service, and the differences between them.

3. iii
Table of Content
1 Literature ....................................................................................................................................... 1
1.1 Quality of Service ................................................................................................................ 1
1.1.1 Quality of Service Parameters.................................................................................. 1
1.2 Grade of Service................................................................................................................... 2
1.2.1 Criteria related to Grade of Service.......................................................................... 3
1.3 Table of differences between Quality of Service and Grade of Service.............................. 4
2 Conclusion..................................................................................................................................... 5
3 Reference....................................................................................................................................... 6

4. 1
1 Literature
1.1 Quality of Service
Quality of Service refers to traffic prioritization and resource reservation control mechanisms. It has
ability to provide different priority to different applications, users, or data flows.
1.1.1 Quality of Service Parameters
To achieve a proper quality of service several aspects and parameters of the network service are
taken into consideration:
 Packet loss
 Bit rate
 Throughput
 Transmission delay
 Availability
 Jitter
 Bandwidth
Packet Loss
Packet loss occurs in the network mainly due to dropping packets at routers, transmission errors and
routing processing decisions. For example, when packets are dropped during real-time
communication, such as a voice or video calls, these sessions can experience jitter and gaps in
speech.
Bit rate
The bit rate is the number of bits that pass a given point in a network in a given amount of time
Throughput
It is an important indicator of the performance and quality of a network connection. For example: a
high ratio of unsuccessful message delivery will ultimately lead to lower throughput and degraded
performance.
Transmission delay
The delay of a network specifies how long it takes for a bit of data to travel across the network from
one node or endpoint to another.
Availability
This parameter specifies the time constraints for equipment and system to execute without disruption
or failure. Normally considered during the network design.

5. 2
Jitter
It is the delay variation experienced by packets and results of network congestion, timing drift and
route changes. For example, too much jitter can degrade the quality of voice and video
communication.
Bandwidth
It is the capacity of a network communications link to transmit the maximum amount of data from
one point to another in a given amount of time.
Low bandwidth impacts the ability to deliver high-bandwidth content such as streaming high
definition video and slows down file transfers.
QoS optimizes the network by managing bandwidth and setting priorities for applications that
require more resources than others.
Each of these factors impacts the quality of service that the network presents to applications.
1.2 Grade of Service
Grade of Service (GoS) refers to a set of indicators that assess the capability of a resource or
resource group (channels, processing, etc.) in a given service as specified. Examples of indicators
are: lockout, delay, processing capacity etc.
So basically it is a measure of the probability that a percentage of offered traffic will be blocked or
delayed
Blocking and delay are caused by the fact that the traffic handling capacity of a network or network
component is finite and that the demand traffic is stochastic by nature.
The users of telecommunication services can experience the effects of GoS parameters depending on
their perception of events such as:
 Failure of a call demand or excessive delay to satisfy a call demand;
 Failure of call attempts or excessive delay to satisfy call attempts;
 Failure of automatic re-attempts or excessive delay to satisfy automatic re-attempts.
This may happen due to channel congestion or non-availability of a free channel.
A higher grade of service implies high probability of loss (blocking probability is the chance that a
subscriber will be denied service due to lack of resources).
In other words, a large grade of service indicates a poor service offered to the customer, as the
probability of packet or calls being blocked or delayed is high.

6. 3
1.2.1 Criteria related to Grade of Service
Blocking criteria
Blocking criteria are often used for the dimensioning of switching networks and interoffice trunk
groups. For a system designed on a loss basis, a suitable GOS is the percentage of calls which are
lost because no equipment is available at the instant of call request.
If the design of a system is based on the fraction of calls blocked (the blocking probability), then the
system is said to be engineered on a blocking basis or call loss basis. Blocking can occur if all
devices are occupied when a demand of service is initiated.
Delay criteria
Delay criteria are used in telephone systems for the dimensioning of registers. In waiting system, a
GOS objective could be either the percentage of calls which are delayed or the percentage which are
delayed more than a certain length of time.
If the design of a system is based on the fraction of calls delayed longer than a specified length of
time (the delay probability), the system is said to be a waiting system or engineered on a delay basis.
Grade of Service can be measured using the following equation:
GoS = (Number of blocked calls)/(Total offered calls)

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1.3 Table of differences between Quality of Service and Grade of Service
Quality of Service (QoS) Grade of Service (GoS)
Description Refers to traffic prioritization and
resource reservation control
mechanisms.
Refers to a set of indicators that
assess the capability of a
resource or resource group
(channels, processing, etc.) in a
given service as specified.
Parameters Packet loss
Bit rate
Throughput
Transmission delay
Availability
Jitter
Bandwidth
Lockout/Blocking
Delay
Processing capacity
Implementation/
Measure
Implemented by using
Scheduling/Queues, such as:
First in first out (FIFO), Round
robin (RR), Priority queuing
(PQ), Weighted fair queuing
(WFQ), etc.
Measured by the difference of
the number of offered calls to the
total offered calls

8. 5
2 Conclusion
Based on our research we conclude that to achieve and maintain a given Qualility of Service and to
limit Grade of Service since a higher grade of service implies high probability of loss , the operator
must ensure that sufficient telecommunications circuits or routes are available to meet a specific
level of demand.

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3 Reference
Techopediacom. (c2019). Techopediacom., from //www.techopedia.com/definition/9049/quality-of-
service
Joberto martins, J.M. (c2007). Quality of Service in IP Networks. In Jobertomartins, J.M (Ed),
Telecom (pp. ). Brazil: .