Analysis of Quality of Service in Wimax networks

Table 1 WiMAX/802.16 QoS Model 
 Description 
Applications 
Unsolicited Grant 
Service (UGS) 
For Constant Bit Rate 
(CBR) and delay-
dependent applications 
VOIP 

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Real-Time Polling 
Service (rtPS) 
For Variable Rate and 
delay dependent 
applications 
Streaming audio, 
Streaming video 
Extended Real-Time 
Polling Service (ertPS) 
For Variable Rate and 
delay dependent 
applications 
VOIP with silence 
suppression 
Non-real-time Polling 
Service (nrtPS) 
Variable rate and non-real 
time applications 
FTP 
Best Effort (BE) 
Best Effort 
E-mail, web traffic 
These service flows can be created, changed, or deleted by the issuing 
Dynamic Service Addition (DSA), Dynamic Service Change (DSC), and Dynamic 
Service Deletion (DSD) messages. Each of these actions can be initiated by the 
Subscriber Station (SS) or the Base Station (BS) and are carried out through a two or 
three-way-handshake. For example, a new service flow initiated by the SS is built as 
follows. When SS detects the emergence of a new service flow, it will calculate the 
available resources to determine whether a DSA request will be sent or not. Upon 
reception of the DSA request, the BS verifies whether this request can be supported, 
and sends a DSA response. Based on the DSA response, the SS sends a DSA 
acknowledgement and enables the new service flow if the request is approved. The 
standard provides some rules to classify DiffServ IP packets into different priority 
queues based on IP QoS indication bits in IP header. So, in general, the QoS 
architecture of IEEE 802.16 can support both IntServ and DiffServ. 
.

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