VoIP and WiMAX are in their respective fields pose a threat to traditional techniques and challenges. Their combination of the two will also put forward on the development of new communication technology requirements, create new effects.

  Priority to support VoIP services Is on WiMAX, VoIP voice service as the basic type of business must be given priority support.

WiMAX network based on IP protocol, the main provider of broadband data services, but only provide the traditional Web browsing and other broadband data services, operators can not satisfy the requirements and market expansion, therefore, WiMAX Forum Application Working Group (AWG ) for a variety of new and different QoS requirements of the business, of which VoIP is a priority to support the business type. In summary, we can see, VoIP business development system from fixed to mobile systems development, WiMAX system consists of the evolution of voice services to data services, both in promoting development, system integration point is WiMAX VoIP application.

VoIP services require the system to guarantee bandwidth, delay and delay jitter control in a certain range, there is no QoS support system can not meet these requirements. Therefore, WiMAX system difficulty lies in the VoIP business VoIP session end to end QoS support system capabilities, including VoIP service flow establishment time permits, session after session is established consultation and radio resource allocation and scheduling, particularly in the mobile environment, users from a base station to another base station, switching the data packet loss and delay the process must be controlled strictly the scope of QoS can be maintained after switching. End to end QoS solution includes two aspects: the air interface, QoS capabilities and the network side QoS architecture.

-End QoS solution WiMAX air interface QoS mechanism in the MAC layer. QoS mechanism consists of two parts, a section on business flow management, which provides an implementation mechanism for uplink and downlink QoS management. The other is the corresponding QoS assurance mechanisms, including the scheduling algorithm, buffer pool management and traffic control, in the agreement of these methods are not defined and elaborated by the equipment manufacturer's specific implementation decisions. Traffic management includes the following:

* Connection-oriented service, MAC layer for each connection.

* Air interface of the five service types and the associated QoS parameters, these five types are: non-business bandwidth allocation request (UGS), real-time polling service (rtPS), extended real-time polling Business (ExtendedReal-time PollingService, ertPS), non-real-time polling service (nrtPS) and do what business (BE).

* QoS for each user-defined parameters, including rates, delay and other indicators.

* Allow the flow of new business strategy for the establishment of the conditions.

Air interface QoS implementation mechanism and classification are closely related, first by collecting (CS) to the upper layer of IP packets sent and a connection identifier (CID) identifies the service flow associated with them, and formed MAC packets, packet QoS service types and the corresponding parameters are included in CID, making each data packet before making scheduling requests with the appropriate QoS. IEEE802.16MAC agreements on the QoS support is divided into three parts: first create the initial service flow and service flow QoS parameter configuration; and dynamic management of the business flow, including the dynamic business increased (DSA), dynamic business change (DSC ) and dynamic business to delete (DSD); last in the communication process of the MAC packet data unit (PDU) based service flow classification and distinction between the type of priority for scheduling.

Side area network, WiMAX Forum NWG specification of network architecture for supporting QoS empty the five kinds of type definition of the network QoS logic entities, triggering processes and corresponding information, through the BS and ASN allocation within QoS control unit, which will be based on the IEEE802.16 standard QoS architecture is extended. WiMAX network QoS QoS functional model includes the following functional units:

* QoS policy database. SS attribution NSP strategy to maintain a predefined database, for authentication and authorization requests for WiMAX business.

* Applications AF. SS NSP supports the attribution of applications. SS application layer control protocol can interact with the AF, as a response, AF may issue a WiMAX service flow incentives to PF.

* SFM. Business Flow Management (SFM) within the logical entity in the ASN, which is responsible for creating, licensing, activation, modification and deletion of service flows. It is controlled by the license (AC) function and composition of the associated local resource information.

* SFA. Traffic authority (SFA) within the logical entity in the ASN, which is based on resource management strategies for network-level admission control. SFA by a QoS policy database and the related strategy function blocks (PF) component. The policy database in the AAA process, the ownership of NSP from the user loads the user predefined QoS attribute information.

QoS policy database is located within the ASN. Through the AAA process, the user attributes can be associated with the QoS information from the ownership of the predefined database NSP sent to the ASN. QoS across the region access to information only through the interface or R5 R3 interfaces, and QoS properties must be consistent with the original.

The user's QoS properties can be considered only for the air interface MAC connection, that is, the QoS property does not require specific access network and core network QoS Implementation.

Access network and core network QoS Implementation and fixed network QoS mechanisms to achieve relevant. There are technical bottleneck

We can see WiMAX network to support VoIP and other QoS requirements of the business side from the air exported to the network has established a relatively perfect QoS mechanism and structure, but some technical issues still not clear, for example, VoIP business within the ASN, ASN to move under the QoS guarantee mechanism, the network structure integrity and reliability, security and authentication, etc., are not limited to WiMAX system, for any wireless system based on IP protocols are the same problems exist So WiMAX technology study on these issues for VoIP service applications in the mobile communication system development is important, and we look forward to these problems and breakthroughs.

VoIP and WiMAX to achieve a good combination of strengths, what they want, but also a good fit in the trend of development of communication technology. The other hand, the combination of the two still do face some short term can not be completely overcome technical bottlenecks, such as: the protection of QoS in mobile environments

I am Mp3 Player Manufacturers writer, reports some information about double beach towel , cheap sofa slipcover.