Efficient integration OVSF code management strategies in UMTS

Chen, Min-Xiou

doi:10.1016/j.comcom.2008.04.019

Cited by 12 publications

(7 citation statements)

References 18 publications

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“…In the simulation, we use a uniform distribution to randomly select the desired rates. 5. Each data point in the following figures represents an average of at least 20 runs with identical experimental mode, but different randomly generated scenarios.…”

Section: Simulation Resultsmentioning

confidence: 99%

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Graph Model for OVSF Code Placement

Ouyang

Wang

et al. 2010

2010 5th International Conference on Future Information Technology

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The orthogonal variable-spreading-factor (OVSF)-CDMA systems can support multimedia applications with different bandwidth requirements. Code management schemes, including code placement and replacement, significantly impact the code utilization of the system. Many researches have studied these two closely related problems and are solving them independently. For replacement, the optimality concerns the minimization of the reassignment number. There is no definition about the placement optimality yet.We formally define the placement optimality for code placement schemes and presented a novel graph model, constrained independent dominating set problem (CIDP), which is proved to be NP-complete for general graphs. A unified algorithm is provided to firstly address both OVSF code placement and replacement issues at the same time which achieves placement optimality in linear time complexity. This demonstrated that OVSF code placement optimality problem is in P. Another simple and practical unified solution is presented and is shown to be reasonably effective.

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Section: Simulation Resultsmentioning

confidence: 99%

“…Chen [5] presented a fast and efficient code word generation method for multiple codes assignment system. Their method can find the optimal code word under the constraint of an assigned code amount, under the constraint of a maximal resource waste ratio, and under the constraint of realistic situation of the current residual codes.…”

Section: Related Workmentioning

confidence: 99%

Graph Model for OVSF Code Placement

Ouyang

Wang

et al. 2010

2010 5th International Conference on Future Information Technology

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“…In the DCA scheme, the blocking probability is reduced using reassignments based on the cost function. The multicode scheme [16] derives the optimal code under the constraints of allocated code amount and maximal resource wastage ratio. In FSP, the code tree is divided into a number of subtrees according to the input traffic distribution.…”

Section: Existing Ovsf Code Assignment Designsmentioning

confidence: 99%

“…The multirate multicode compact assignment [15] scheme uses the concept of compact index to accommodate users with differentiated QoS requirements. The multicode scheme [16] derives the optimal code under the constraints of allocated code amount and maximal resource wastage ratio. It gives superior performance using two and three codes in a multicode with a crowded-groupfirst strategy.…”

Section: Existing Ovsf Code Assignment Designsmentioning

confidence: 99%

Reducing code wastage in orthogonal variable spreading factor‐based wideband code division multiple access networks

Saini

Gupta

Joshi

2011

Int J Communication

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Most third-generation and beyond wideband code division multiple access networks use the orthogonal variable spreading factor code tree for channelization codes. The codes in this code tree are limited and the performance of a wireless network depends upon the code assignment for new calls. In this paper, we introduce a term called 'wastage capacity', which gives us the amount of wastage caused when a code (single or multiple) with a data rate higher than the rate of the incoming call is assigned to it. We suggest two methods to keep wastage capacity below an arbitrary threshold value or zero. In the first method, we devised an algorithm in which wastage up to a certain threshold would be tolerated and the minimum rakes to get this wastage capacity were identified. In the second approach, we reduced the wastage capacity to zero irrespective of the number of rakes at the expense of higher cost and complexity.

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“…In dynamic code assignment [19], the multimedia rates are differentiated by QoS parameters like delay, jitter, bandwidth and reliability. The multi code design [20] identifies the optimal code for a given set of allocated codes and specified maximal resource wastage ratio. The superior performance of multi code design is achieved using two or three codes with crowded-group-first facility.…”

Section: Related Workmentioning

confidence: 99%