Joint Rate Selection Research Articles

Multi-Cell Cooperative Scheduling for Network Utility Maximization With User Equipment Side Interference Cancellation

Downlink inter-cell interference is a major limiting factor in current cellular systems. Several trends exacerbate the interference problem: cells become denser, more heterogeneous, and are more randomly deployed. To tackle this problem, there are many pure network-side solutions proposed, e.g., eICIC and feICIC in 3GPP LTE. However, these solutions are less spectrally efficient because the interferer usually needs to mute or reduce power to keep its interference power to victims below a tolerable level. In this paper, we consider an alternative solution in which the user equipment may perform interference cancellation (IC). In theory, this is a more spectrally efficient scheme as compared with the pure network-side solutions. In practice, however, to fully exploit the benefit of IC, the network should adopt some IC-aware scheduling rules. We propose a multi-cell joint scheduling, joint rate selection and power allocation problem in an IC-enabled network, trying to maximize the network utility. To make our solutions practical and readily deployable, we consider different settings. We explore both theoretically optimal IC scheme and the more practical symbol-level IC. On the other hand, we propose both dynamic and semi-static solutions, and compare them. Our simulation results show that while the average throughput increases by only around 10%, cell edge users can gain more than 50%.

Coding-Based Data Broadcasting for Time-Critical Applications With Rate Adaptation

In this paper, we dynamically select the transmission rate and design wireless network coding to improve the quality of services such as delay for time critical applications. In a network coded system, with low transmission rate and hence longer transmission range, more packets may be encoded, which increases the coding opportunity. However, low transmission rate may incur extra transmission delay, which is intolerable for time critical applications. We design a novel joint rate selection and wireless network coding (RSNC) scheme with delay constraint, so as to maximize the total benefit (where we can define the benefit based on the priority or importance of a packet for example) of the packets that are successfully received at the destinations without missing their deadlines. We prove that the proposed problem is NP-hard, and propose a novel graph model to mathematically formulate the problem. For the general case, we propose a transmission metric and design an efficient algorithm to determine the transmission rate and coding strategy for each transmission. For a special case when all delay constraints are the same, we study the pairwise coding and present a polynomial time pairwise coding algorithm that achieves an approximation ratio of 1 - 1/e to the optimal pairwise coding solution, where e is the base of the natural logarithm. Finally, simulation results demonstrate the superiority of the proposed RSNC scheme.