下一代虛擬私有網路核心技術之研究-子計畫二：下一代虛擬私有網路計價收費 技術之研究(2/2)
Date Issued
2003-07-31
Date
2003-07-31
Author(s)
DOI
912219E002033
Abstract
This two year research included three tasks: (1) research
on QoS-based virtual private network (VPN) technology, (2)
the design of pricing scheme for VPN service, and (3)
research on the synchronization problem of OFDM system
In the first year, we adopted differentiated service
(DiffServ) architecture to design and implement a QoS VPN
experimental environment. We designed a QoS VPN
router and a service broker by combining packet
classification, traffic shaping and packet scheduling of
DiffServ routing with encryption, authentication and
tunneling of VPN. They were implemented into a
Linux-based experimental network, where a VPN service
with per flow-based QoS can then be provided.
In the second year, a decision model was developed for
ISP pricing between two types of Internet services:
bandwidth guaranteed VPN and best effort public network
(BEPN). The VPN users are corporates and their
employees, where a corporate subscribes and pays for the
VPN service while its employees are the actual users. Each
VPN user is guaranteed a minimum bandwidth. The BEPN
users are the general public and have no QoS guarantee.
Under this setting, our study found that the price level
affects the number of subscribers. The usage behavior of a
VPN user is insensitive to the pricing policy and the
probability that a BEPN subscriber will actually use the
service depends on the bandwidth level to share among
BEPN subscribers. Bandwidth is shared between VPN and
BEPN but the ISP puts the bandwidth guarantee to VPN
users in a high priority. We also implemented the pricing
scheme and added a NTOPTM-based network traffic
metering and accounting module to the QoS VPN
experiment environment.
In addition, we studied the synchronization problem of
OFDM system, including carrier offsets caused by both
frequency and time. We designed a hybrid frequency offset
correction method that significantly improved for the OFDM
system with low signal-to-noise ratio and short cyclic prefix.
Subjects
Virtual Private Network
DiffServ
Quality of
Service
Service
Pricing
OFDM
offset estimation
Publisher
臺北市：國立臺灣大學電機工程學系暨研究所
Type
report
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