A key feature of the Long-Term Evolution (LTE) system is that the packet scheduler can make use of the channel quality information (CQI), which is periodically reported by user equipment either in an aggregate form for the whole downlink channel or distinguished for each available subchannel. This mechanism allows for wide discretion in resource allocation, thus promoting the flourishing of several scheduling algorithms, with different purposes. It is therefore of great interest to compare the performance of such algorithms under different scenarios. Here, we carry out a thorough performance analysis of different scheduling algorithms for saturated User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) traffic sources, as well as consider both the time- and frequency-domain versions of the schedulers and for both flat and frequency-selective channels. The analysis makes it possible to appreciate the difference among the scheduling algorithms and to assess the performance gain, in terms of cell capacity, users' fairness, and packet service time, obtained by exploiting the richer, but heavier, information carried by subchannel CQI. An important part of this analysis is a throughput guarantee scheduler, which we propose in this paper. The analysis reveals that the proposed scheduler provides a good tradeoff between cell capacity and fairness both for TCP and UDP traffic sources

Offering throughput guarantees for cellular wireless networks, carrying real-time traffic, is of interest to both the network operators and the customers. In this article, we formulate an optimization problem which aims at maximizing the throughput that can be guaranteed to the mobile users. By building on results obtained by Borst and Whiting and by assuming that the distributions of the users' carrier-to-noise ratios are known, we find the solution to this problem for users with different channel quality distributions, for both the scenario where all the users have the same throughput guarantees, and the scenario where all the users have different throughput guarantees. Based on these solutions, we also propose two simple and low complexity adaptive scheduling algorithms that perform significantly better than other well-known scheduling algorithms. We further develop an expression for the approximate throughput guarantee violation probability for users in time-slotted networks with the given cumulants of the distribution of bit-rate in a time-slot, and a given distribution for the number of timeslots allocated within a time-window.

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A number of scheduling algorithms for LTE downlink have been proposed and evaluated leveraging the flexibility of the resource allocation in both the time and the frequency domain. However, the existing literature falls short when it comes to schedulers that provide throughput guarantees. In this paper, we contribute to fill this gap by implementing a scheduling algorithm that provides long-term throughput guarantees to the different users, while opportunistically exploiting the instantaneous channel fluctuations to increase the cell capacity. We perform a thorough performance analysis comparing this algorithm with the other well known algorithms by means of extensive ns-3 simulations, both for saturated UDP and TCP traffic sources. The analysis makes it possible to appreciate the difference among the scheduling algorithms, and to assess the performance gain, both in terms of cell capacity and packet service time, obtained by allowing the schedulers to work in the frequency domain

The wide flexibility of LTE resource allocation scheme has led to the definition of various schedulers that attempt to maximize the quality of the service offered to the different users, depending on their channel conditions. Unfortunately, providing service guarantees in dynamic channel conditions typically requires a cost in terms of spectral efficiency of the transmission resource allocation. In this work, we investigate this tradeoff and propose a resource allocation scheme that adapts the service level guarantees to the average channel conditions of the users, in order to provide fair resource allocation among users with homogeneous channel conditions, while improving the cell spectral efficiency. A performance analysis is carried out by comparing the proposed scheduler with other well known schedulers. Results show that the proposed method can improve the cell capacity, while guaranteeing long-term throughput fairness among users of the same class. In addition, we analyze the short-term throughput provided by the proposed scheduler and provide a semi-analytical model to assess the gap with respect to the long-term performance