Abstract
Deploying long term evolution (LTE) system into unlicensed spectrum for offloading faces two challenges: 1) the metrics of instantaneous performance to characterize user satisfaction are no longer applicable due to non-contiguously available channel and 2) in a light traffic scenario, the channel utilization is low due to the added padding bits of simultaneously scheduled users. To tackle these two issues, dynamically configuring channel occupancy duration (COD) and flexibly allocating subcarriers are needed to design for the LTE system operating in unlicensed spectrum (LTE-U system). In this paper, the channel utilization in the COD and a unified user satisfaction are first defined to characterize the performance of LTE-U system. Then, a time-frequency two-dimention optimization problem is formulated to maximize the weighted sum of the two defined performance indexes. To achieve the tradeoff between the two performance indexes, a control factor is introduced. By using Lyapunov optimization and Dinkelback theory, an optimal time-frequency resource management algorithm is developed. The results show that the proposed algorithm outperforms the baselines, as the algorithm can flexibly balance the two performance indexes of the LTE-U system for diverse applications.
Highlights
In recent years, the proliferation of intelligent terminals and diverse applications have led to a dramatic increase in data traffic [1], [2]
For an orthogonal frequency division multiple access (OFDMA)-based long term evolution (LTE)-U system coexisting with a legacy unlicensed system in unlicensed spectrum, this paper studies its resource management that maximizes the weighted sum of the two newly defined performance indexes under the condition of time-varying channel, the constraint of maximum-allowed access period and various user satisfaction requirements
To meet user’s required data transmission rate and enhance the channel utilization, this paper proposes a time-frequency two-dimensional resource management scheme to dynamically adjust channel occupancy duration (COD) length and subcarrier allocation according to instant channel conditions, data arrival rates and user satisfactions
Summary
The proliferation of intelligent terminals and diverse applications have led to a dramatic increase in data traffic [1], [2]. To meet user’s required data transmission rate and enhance the channel utilization, this paper proposes a time-frequency two-dimensional resource management scheme to dynamically adjust COD length and subcarrier allocation according to instant channel conditions, data arrival rates and user satisfactions. In the problem expression, the weights of the newly defined channel utilization and user satisfaction performance indexes are adjustable to achieve application-specific requirement The objective of this optimization problem is to maximize the weighted sum of these two performance indexes in a time-averaged sense, and to find the optimal and dynamical COD lengths and subcarrier assignment indicator matrices for all the frames.
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Published Version
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