... eg. ToS field of IP
o Problem
l how to avoid everybody sendinghigh priority packets?
Queue Management
1
Quality ofService in IP
Networks
CH-1015 Ecublens
http://icawww.epfl.ch
Prof. Jean-Yves ... Fast Retransmit
o Probability p of choosing a given flow is proportional to the rate of the
flow
l more packets of that flow, higher probability of choosing one of its packets
Queue Management
16
FIFO
o ... duration
o Burst duration - S sec
o Size of the bucket - B bytes
o Maximal departure rate - p bytes/s
o Token arrival rate - r bytes /s
l burst of B + r S bytes
l burst of pS
l B + rS = pS → S = B/(r -...
... that information instead of when a packet arrives. The
140
Chapter 9. QualityofService
Quality ofservice (QoS) is an often-used and misused term that has a variety of meanings. In this book, ... has a variety of meanings. In this book, QoS
refers to both class ofservice (CoS) and type ofservice (ToS). The basic goal of CoS and ToS is to achieve
the bandwidth and latency needed for ... classes of service.
You can base policies on IP addresses, port numbers, protocols, or the size of packets. You can use one of
these descriptors to create a simple policy, or you can use all of...
... or
more of the total number of RF channels required on a
multiple link transport system for a specified amount of
user grade of service. The percentage reduction
depended on the number of radiating ...
5
A
N
N!
B=
i
i!
i=0
N
A
∑
Improving Grade ofService (GOS) While
Reducing RF Channels
Wireless service providers are adopting new deployment strategies
to reduce network costs and improve qualityof service. In one
urban ... “grade ofservice (GOS), which is the
acceptable amount of network blocking of incoming call
attempts. Typical wireless network designs in the United
States provision channels to provide voice services...
... Congestion avoidance, additive increase
24.23
24-5 QUALITYOF SERVICE
24-5 QUALITYOFSERVICE
Quality ofservice (QoS) is an internetworking issue
Quality ofservice (QoS) is an internetworking issue ... SERVICES
24-7 INTEGRATED SERVICES
Two models have been designed to provide qualityof
Two models have been designed to provide qualityof
service in the Internet: Integrated Services and
service ... Four cases of congestion
24.2
24-1 DATA TRAFFIC
24-1 DATA TRAFFIC
The main focus of congestion control and qualityof
The main focus of congestion control and qualityof
service is
service is...
... 105
5.9 References 106
6 Qualityofservice 107
6.1 Introduction 107
6.2 Routing in mobile ad hoc networks 110
6.3 Routing with qualityofservice constraints 112
6.4 Qualityofservice routing in ... independent.
1.5 Qualityof service
All the vulnerabilities enumerated in Section 1.3 above are potential sources of
service impairment in ad hoc networks and hence may degrade the ‘ quality of
service ’ ... associated with providing qualityofservice (QoS)in
ad hoc networks. It should be pointed out that security and qualityof service
are two distinct attributes that are independent of each other in general....
... 2011, 2011:9
http://jwcn.eurasipjournals.com/content/2011/1/9
Page 7 of 13
RESEARCH Open Access
Quality ofservice implications of power control
and multiuser detection-based cross-layer design
Ulrike ... part of the frame is related to a contention phase
and consists of several pairs of minislots. Each minislot
is divided into the transmission of an RTS and a CTS
signal. The second part of the ... rate; PBOA: Progressive
Backoff Algorithm; PHY: physical layer; QoS: qualityof service; SINR: signal-to-
interference-and-noise-ratio.
Author details
1
Institute of Communication Networks, Technische...
... number of bits per symbol of modulation. This number depends on the
MCS used.
c: represents the code rate of the Forward Error Correction (FEC).
VI Contents
Part 2 QualityofService ... the classification of the scheduling mechanisms provided in the Section
Quality ofService and Resource Allocation in WiMAX
4
3. Then, the performance evaluation of these algorithms ... to present state of the art on WiMAX Technology. It has
been constructed with the support of many researchers around the world, working on
resource allocation, qualityofservice and WiMAX...
... of a cellular WiMAX network where a
number of base stations need to communicate simultaneously with their respective active
users
1
. Each of these u sers has typically a certain QualityofService ... Schemes for WiMAX Networks
Quality ofService and Resource Allocation in WiMAX
92
requirements. The packet scheduler provides scheduling for different classes of services for
a single user. ... WiMAX Networks 9
ensure some level of fairness among users, one can use the maximization of a weighted sum
of users achievable rates as the criterion of optimization of the resource allocation.
In...
... analysis of the network in the limit of large number of users.Theaimof
this approach is to obtain op timal values of the resuse factor that no longer depend on the
particular configuration of the ... IEEE802.11e enhancement (IEEE802.16e, 2006), that allows
the quality- of- service management.
Service and performance metric. The main objective of this chapter is to derive and compare
the performance ... the knowledge of t he
signal -quality, the amount of users, the scheduling policy, etc. This entails that in the case of
UE initiated connections, the UE has a complete knowledge of the expected...
... format of the OFDMA slot is 8 data subcarriers
of 6 OFDM symbols. The total number of OFDMA slots in a mobile WiMAX frame
corresponds to S
× T
s
where S =
L
d
8
and T
s
is the number of OFDM symbol ... link. WiMAX also defines a
concept of a service flow. A service flow is a unidirectional flow of packets with a particular
set of QoS parameters and is identified by a service flow identifier (SFID). The ... constraints of each connection. The mapping mechanism is left to the choice of the
provider.
3. State of the art
3.1 Bandwidth sharing strategies: background
To maintain a qualityofservice required...
... studying the impact of different parameters on the
performance of contention-based services of IEEE 802.16.
We evaluate the impact of the number of SSs (N) and the initial backoff window (W)on
various ... traffic load of an SS, ρ. In the following, we will develop the outer set of fixed point
equations for ρ.
3.2 Mean service time of an REQ
This subsection presents the details of Block B of Fig. 2, ... until the start of the
request interval where the backoff of the first attempt is initiated, and its backoff process from
the beginning of the first request interval until the beginning of the request...
... providers.
With regard to QualityofService (QoS) control, the WiMAX system provides service
differentiation based on the combination of a set of communication service classes
supported by ... Policy Scheme
Quality ofService and Resource Allocation in WiMAX
210
quality was maintained during the change of BS. The SS that experienced a hard handover
did not receive 5% of the packets, ... This involves defining three mobility profiles: high,
medium and low. Each mobility profile will be associated with the precise period of time
Quality ofService and Resource Allocation in WiMAX...