End-to-end QoS policy for WiMAX network

In recent years, the mobile communication field presents the trend of data and broadband, WiMAX adopts multicarrier modulation technology, which can provide high-speed data service, and has the characteristics of high frequency spectrum resource utilization, high efficiency bandwidth utilization and large coverage range. The cost of WiMAX is relatively low, it can provide convenience for individuals, families and enterprises, excellent mobile multimedia broadband service and high-speed wireless data transmission. These characteristics of WiMAX technology accord with the development trend of mobile communication, which has aroused wide concern of the industry. Through WiMAX network to carry out multimedia services, we need to solve the end-to-end QoS problem, so that users can obtain satisfactory service, but also effective use of network resources. Currently, many standard organizations and equipment manufacturers are conducting research and development work in this field.

End-to-end QoS Management for WiMAX networks

The IEEE802.16 standard does not define end-to-end QoS mechanisms, and one of the keys to promoting WiMAX technology is to provide End-to-end QoS guarantees for multimedia services such as voice and video. To solve this problem, we first need each network unit to effectively manage the local resources to provide the End-to-end service load to meet the business needs, and at the same time, the QoS parameter mapping of the application layer will load the corresponding attribute parameter. WiMAX network hosting consists of two parts: wireless bearer and IP transport bearer. The wireless bearer provides the service through the IEEE802.16 mechanism, the IP transport host uses the technology of IP network such as DiffServ and MPLS to guarantee QoS.

The WiMAX network model includes the following network entities: Mobile User terminals, ASN (Access service network) access network, CSN (Connectivity Service network) Core service network, as shown in Figure 1. User terminals include the application client and MSS (Mobile Subscriber Station). The QoS management functions that each entity should have in a WiMAX network are as follows:

1 translation mapping: Located in the user terminal, ASN and CSN, in the terminal is mainly responsible for application layer QoS and WiMAX wireless load parameters between the mapping; within the ASN, responsible for the conversion and mapping of QoS information and ASN internal QoS parameters in the service request, This includes mapping of transport-hosted (IP-layer) and wireless-hosted (Mac-and physical-layer) parameters, and conversion of the application-tier QoS parameters to service request information in CSN. (Computer science)

2 access control: Located in user terminals, ASN and CSN, check whether the state of the hosted resource (including transmission resources and wireless resources within the ASN) can meet the QoS of the Application service request.

3 User signing information check: In the ASN, check whether the user's QoS signing information is allowed to accept the requested business, the signing information usually includes the permitted types of business, the largest number of business and so on. The QoS signing information is extracted from the CSN during the initial user access and is stored in the ASN.

4 SLA check: In ASN, where SLAs refer to QoS agreements between ASN and CSN, including service type, bandwidth throttling, QoS level, maximum number of users, and so on. The ASN is responsible for checking that business requests do not exceed SLA limits.

5 Resource Manager: Located in user terminals, ASN and CSN, manage wireless resources and transfer resources, according to service requirements and network resources status, dynamically allocate the host resources. According to the QoS requirements of the application layer, the corresponding transport layer is built. For example, in the wireless side according to the business type to establish the corresponding service flow hosting, in the transmission network side reserve the corresponding bandwidth resources.

6 mac Bearer: Located at User terminal and ASN, provide wireless bearer QoS guarantee mechanism, mainly by IEEE802.16 defined service flow QoS parameters to identify, mainly including service type, rate, delay, jitter, priority and other parameters.

7 Wireless Physical Layer: Located in user terminals and ASN, provide physical layer load, including channel bandwidth, modulation and coding methods and other parameters.

8 IP Transport hosting: Located in ASN and CSN, providing QoS hosting of IP layer, the main QoS parameters for IP network are IP bandwidth (corresponding to the maximum business rate), and IP packet priority (such as DSCP parameter in DiffServ network).

How WiMAX and IMS realize interconnection

IMS was first proposed in the 3GPP R5, the purpose of introducing IMS in Mobile network is to provide mobile multimedia service, the IMS architecture is based on SIP protocol, SIP is an application layer control and signaling protocol, it provides session establishment and QoS negotiation mechanism of application layer, and can provide different application by extending SIP protocol. , support different access mode, can serve for fixed network user, also can serve for mobile user. The IMS technology based on SIP realizes complete operation and control separation and access independence, because of this important characteristic, it has been paid much attention by the industry.

At present, both 3GPP mobile network and NGN fixed network adopt IMS architecture and SIP protocol to provide multimedia service, and it is widely accepted that IMS will become one of the important technical directions for network integration and core control layer development. IMS System provides QoS assurance for user Service, RFC3312 Error! The reference source was not found. This paper defines the mechanism of QoS Resource Reservation during SIP session establishment, and realizes the End-to-end QoS negotiation in IP network. WiMAX as the next generation of broadband wireless access technology, can also provide access to fixed and mobile users, IP network as a transport bearer, but also need to realize the interconnection with the IMS network, so as to enrich the provision of business, enhance the user's attractiveness.

WiMAX and IMS interconnect models with bugs like! The reference source was not found. As shown, IMS can be located in the operator's private network, directly connected to the carrier's backbone network, or in a Third-party network, through a specific application gateway, through the Internet interconnection. In the WiMAX architecture, IMS is located in CSN to differentiate it from the wireless access ASN.

application Example Analysis

After the solution is connected with the IMS, the SIP client software is installed in the WiMAX terminal, which can provide various kinds of business that can be realized in the IMS network, such as IP Phone (VoIP), rendering and instant message, Video conferencing (conferencing), Push to Talk, Short message (SMS) and so on. The following is an example of an application of Alcatel Shanghai Bell WiMAX Network and the NGN IMS Interconnect, as shown in Figure 2.

Fig. 2 Wimax-ims Application Example

In this solution, CSN is the NGN Core network integrated with IMS, 5020(call session Controller) completes the S- function, SBC (session Border Controller) Completes the function of  and IMS Access Gateway, and media gateways are connected with traditional PSTN networks. SBC features both user and control surfaces, and as an IMS access point, SBC is responsible for QoS negotiation with WiMAX access Gateway, in this case SFA is located in AGW. It should be noted that the user movement between BS is transparent to the SBC and does not affect existing network devices. Through the above way, WiMAX end users can easily enjoy the IMS service.

Conclusion

WiMAX technology provides a flexible QoS mechanism, and can easily carry out a variety of IP multimedia services by combining with the existing network technology effectively. WiMAX network standards are still not perfect, the interconnection caused a certain degree of difficulty, WiMAX standards Organization is committed to this area of research. WiMAX technology represents the future development direction of mobile communications, with the continuous improvement of standards, WiMAX technology will certainly be widely used.