Improving the Competitive Ratio of the Online OVSF Code Assignment Problem
نویسندگان
چکیده
Online OVSF code assignment has an important application to wireless communications. Recently, this problem was formally modeled as an online problem, and performances of online algorithms have been analyzed by the competitive analysis. The previous best upper and lower bounds on the competitive ratio were 10 and 5/3, respectively. In this paper, we improve them to 7 and 2, respectively. We also show that our analysis for the upper bound is tight by giving an input sequence for which the competitive ratio of our algorithm is 7− ε for an arbitrary constant ε > 0.
منابع مشابه
Online OVSF Code Assignment with Resource Augmentation
Orthogonal Variable Spreading Factor (OVSF) code assignment is a fundamental problem in Wideband Code-Division MultipleAccess (W-CDMA) systems, which play an important role in third generation mobile communications. In the OVSF problem, codes must be assigned to incoming code requests, with different data rate requirements, in such a way that they are mutually orthogonal with respect to an OVSF...
متن کاملOnline Tree Node Assignment with Resource Augmentation
Given a complete binary tree of height h, the online tree node assignment problem is to serve a sequence of assignment/release requests, where an assignment request, with an integer parameter 0 ≤ i ≤ h, is served by assigning a (tree) node at level (or height) i and a release request is served by releasing a specified assigned node. The node assignments have to guarantee that no node is assigne...
متن کاملEfficient OVSF code assignment strategy in UMTS with Multiple Codes
In order to provide variable data rates in a flexible manner to support applications with different bandwidth requirements, the orthogonal variable spreading factor (OVSF) codes, adopted by the third-generation partnership project technical specifications, are used as channelization codes. This paper considers the environment of using multiple OVSF codes to support a request with any data rate,...
متن کاملMultiple OVSF codes Assignment with Crowded Branch First Strategy in WCDMA Systems
-In this paper, we consider the environment of using multiple OVSF codes to support a request with any data rate. This paper presents the Crowded Branch First strategy for multiple OVSF codes assignment system. Based on the new strategy and the code word generation method, the system can allocate the appropriated codes to each request under the constraint of assigned code amount, and under the ...
متن کاملAn Efficient Dynamic Orthogonal Variable Spreading Factor Code Allocation Approach in WCDMA through Modified Adaptive Genetic Algorithm
Orthogonal Variable Spreading Factor (OVSF) codes would give variable data rate transmissions for different bandwidth supplies in Wideband CDMA (WCDMA) networks. These OVSF codes are used for the channelization of codes in WCDMA. In WCDMA, effective utilization of OVSF codes has become an active area of research as the number of codes is very limited. It is a fact that the successor and predece...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Algorithms
دوره 2 شماره
صفحات -
تاریخ انتشار 2008