Pricing communication networks P9

Chương này diễn tả hiện tượng tắc nghẽn, và những cách thức mà nó có thể ảnh hưởng đến quyết định giá. người sử dụng Internet là đặc biệt quen thuộc với các hiện tượng tắc nghẽn và sự suy giảm chất lượng dịch vụ xảy ra là số lượng người dùng đồng thời tăng. Điều này tương tự các hiệu ứng tắc nghẽn bởi kinh nghiệm lái xe khi cuộc hành trình lần và tăng số vụ tai nạn do xe ô tô ngày càng nhiều trên đường. Trong chương này, chúng tôi hiển thị như thế nào giá...
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Pricing communication networks P9 Pricing Communication Networks: Economics, Technology and Modelling. Costas Courcoubetis and Richard Weber Copyright  2003 John Wiley & Sons, Ltd. ISBN: 0-470-85130-99CongestionThis chapter deals with the phenomenon of congestion, and the ways in which it canaffect pricing decisions. Internet users are especially familiar with the phenomenon ofcongestion and the decline in service quality that occurs as the number of simultaneoususers increases. This is similar to the congestion effects experienced by car drivers whenjourney times and accident numbers increase because more cars are on the road. In thischapter, we show how pricing can be used to control congestion and increase the value ofservices to users. In previous chapters we have neglected the effects of congestion by supposing that thebenefit that a user obtains from a communications service depends only upon parametersof that service and the amount of the service he obtains. We have imagined that if user ibuys a quantity of a service xi at a price p then his net benefit takes the form u i .xi / pxi (9.1)where for user i’s demand we write xi rather than x i , since his demand is one-dimensional.Once we know the users’ demand functions, the suppliers’ cost functions and theirtechnology sets, the problems of maximizing the suppliers’ profit or the social welfarecan be solved by using prices to allocate services to the users who value them most andto match the demand for services to supply. This is all true for a service that has staticallydefined guarantees that may not vary during the life of the service. In this case, congestionis expressed in terms of packet loss rate or packet delay, and a maximum tolerable level ofcongestion is part of the service specification. Call admission control is used to maintaincongestion below this level. Hence u i .xi / in (9.1) denotes the utility of using a quantity ofservice xi that has this level of congestion. When services have contracts with dynamic parameters (e.g. the maximum sending ratemay vary during the life of the service), and there is no strict guarantee on minimumperformance levels, users will be tempted to demand the most that they can from thenetwork. But a decision by the network to grant such requests to all its customers maymake performance intolerable. It is clear that (9.1) fails to capture the effects of the arbitrary levels of congestion that canoccur if the network does not use controls such as call admission to restrict the maximumcongestion level. In modelling congestion, we suppose that when a user receives more ofa service the value of the service deteriorates, as it is experienced by him and all otherusers.220 CONGESTION The models in this chapter are concerned with the effects of congestion and pricing thattake congestion into account. In the case of services sharing a common resource pool,we model congestion by supposing that user i has a net benefit that depends upon theamounts of service demanded by other users. That is, he enjoys net benefit of a formsuch as u i .xi ; y/ pxi (9.2) Pwhere y D i xi =k, for some constant k. Here k parameterizes the resource capacity of thesystem. The intuition is that congestion depends upon the load of the system, as measured Pby y. Full load may correspond to i xi D k. If user i requests a quantity of service that is small compared with the total requests ofall users, then y does not vary much with different choices of xi , and so the problem ofmaximizing (9.2) reduces to that of maximizing (9.1), with y taken as fixed. In this chapterwe suppose y is not fixed, and consider the problem of determining p so that when themarket is in equilibrium we maximize some measure such as social welfare or the serviceprovider’s profit. When a participant in a market can, without suffering penalty, make choices of variablesthat adversely affect the utilities of other participants, we say there is a negative marketexternality. Congestion is a good example of a negative market externality. Positive marketexternalities are also possible. For example, when a consumer purchases a particularmodel of mobile phone he increases the popularity of that phone; its increased popularityencourages the manufacturer to provide spare parts and accessories, making it more valuableto all its owners. Returning to our model of congestion: how can users be po ...