Pricing communication networks P8

Bảo đảm tính phí dịch vụTrong Phần 2.1.5, chúng tôi xác định một dịch vụ được đảm bảo như một cho đó có là hợp đồng giữa các nhà cung cấp dịch vụ và khách hàng. Hợp đồng này quy định các nghĩa vụ cho cả hai bên. Các nhà cung cấp dịch vụ thỏa thuận cung cấp một dịch vụ với các thông số chất lượng nhất định, miễn là lưu lượng truy cập của khách hàng đáp ứng hạn chế nhất định. Nói chung, một hợp đồng cho một dịch vụ đảm bảo có thể cho phép một...
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Pricing communication networks P8 Pricing Communication Networks: Economics, Technology and Modelling. Costas Courcoubetis and Richard Weber Copyright  2003 John Wiley & Sons, Ltd. ISBN: 0-470-85130-98Charging Guaranteed ServicesIn Section 2.1.5 we defined a guaranteed service as one for which there is a contract betweenthe service provider and the customer. This contract specifies obligations for both parties.The service provider agrees to provide a service with certain quality parameters so long asthe customer’s traffic satisfies certain constraints. In general, a contract for a guaranteed service may allow some flexibility. Certain contractparameters, such as maximum peak rate, may be renegotiated and allowed to change theirvalues during the life of the service. For example, the contact might specify that the networkguarantees no information loss so long as the user sends at no more than a maximum rateof h Mbps. The value of h may be renegotiated at the beginning of every minute to besome value between 1 and 2. Thus there is a part of the contract which guarantees no cellloss at a rate of 1. Any extra rate above this must be negotiated. One possibility is thatthe extra rate must be bought in a bandwidth auction. This auction is run by the networkoperator so as to better utilize spare capacity. A second possibility is that the operator postsa price p.t/ and lets the user choose how much bandwidth in excess of 1 he wishes to buy.He sets p.t/ to reflect the present level of congestion in the network. Seeing p.t/, the usermust choose the amount of bandwidth in excess of 1 he would like. Chapter 10 is about charging flexible contracts and pricing methodology that gives usersincentives to make such choices optimally. However, in this chapter we restrict attentionto guaranteed services whose contracts do not allow the users such flexibility. We supposethat all contract parameters are statically defined at the time the contract is established.Equivalently, we restrict attention to that portion of the contract which has no flexibilityand for which the network is bound to provide some minimal requirements, known at thetime the contract is established and persisting throughout its life. In the example above, thisportion of the contract is the obligation to provide a 1 Mbps rate at no cell loss. We use ideasof previous chapters to develop a theory of charging for such contracts. We do this in variouseconomic contexts, such as the maximization of the social welfare or the supplier’s profit. Most interesting guaranteed services have contracts that specify minimum qualities ofservice that the network must provide, such as minimum throughput rate, maximum packetdelay or maximum packet loss rate. This means that the network must reserve resources tomeet the requirements of the active service contracts, and if network resources are finite, thenetwork must operate within its technology set. Recall from Chapter 4 that the technologydefines the set of services and their quantities that it is within the network’s capabilityto provide at one time. In this chapter we analyse, in different economic contexts, the196 CHARGING GUARANTEED SERVICESform of prices that result from considering the particular structure of the constraints oftechnology sets. An important distinction between service contracts for communications services andsome other economic commodities is that the former do not specify fully the resourcesthat are required to produce a unit of output. For example, the resources that are requiredto produce a particular model of personal computer are fixed before its manufacturingstarts, whereas a connection whose service contract specifies only an upper bound on theconnection’s maximum rate may use buffer and bandwidth in a way that can only beknown to the network once the connection ends. The fact that some information is knownonly ‘a posteriori’, rather than ‘a priori’, makes the problem of pricing service contractsquite complex. We will see that by including component of usage in the tariff we canproduce a charge that more accurately reflects the actual resource consumption. This typeof charge can provide a customer with the incentive to change his prospective networkusage in a way that benefits overall system efficiency. Perhaps he might smooth his trafficand make it less bursty, or use some sort of compression scheme to reduce its total volume.If there is no usage component in the charge then customers have no incentive to conserveresources; instead, they may be wasteful of resources and behave in ways that reduce theoverall efficiency and capacity of the network. We argue that flat rate pricing can lead toexactly this sort of waste, and that pricing methods which include a usage charge are to bepreferred. Chapter 4 presented the concept of an effective bandwidth as a proxy for the quantityof network resources consumed by a bursty connection. In Section 8.1 we discuss marketmodels for which it is or is not appropriate to use effective bandwidths as the basis forpricing network connections. In Section 8.2 we investigate the more complex problem ofconstructing tariffs for service contracts. We discuss the pros and cons of flat rate pricingand give justifications for using tariffs that take account of actual network resource usageand charge proportionally to effective bandwidths. As we see in Section 8.3, it is important that the tariffs for service contracts be incentivecompatible. A network can be more competitive and fairer to its users if it presents themwith a range of tariffs, each of which is intended for a specific user type. In the ...