Downlink scheduling in CDMA data networks

Abstract

Packet data is expected to dominate third generation wireless networks, unlike current generation voice networks. This opens up new and interesting problems. Physical and link layer issues have been studied extensively, while resource allocation and scheduling issues have not been addressed satisfactorily.In this work, we address resource management on the downlink of CDMA packet data networks. Network performance (for example, capacity) has been addressed, but user centric performance has not received much attention. Recently, various non-traditional scheduling schemes based on new metrics have been proposed, and target user performance (mostly without reference to wireless). We adapt these metrics to the CDMA context, and establish some new results for the ofitine scheduling problem. In addition, we modify a large class of online algorithms to work in our setup and conduct a wide range of experiments. Based on detailed simulations, we infer that:• Algorithms which exploit "request sizes" seem to outperform those that do not. Among these, algorithms that also exploit channel conditions provide significantly higher network throughput.• Depending on continuous or discretized bandwidth conditions, either pure time multiplexing or a combination of time and code multiplexing strikes an excellent balance between user satisfaction and network performance.• Discrete bandwidth conditions can lead to degraded user level performance without much impact on network performance. We argue that the discretization needs to be fine tuned to address this shortcoming.

Improving TCP/IP Performance over Third-Generation Wireless Networks

“…Differentiation for short flows in wireless networks has also been studied in [23] and [24]. In [24], ForegroundBackground (FB) scheduling [25] is used for scheduling between multiple flows of a single user, and PF scheduling is used for scheduling packets across users.…”

“…In this paper, we propose both new intrauser and interuser scheduling algorithms. In [23], the goal is to minimize the average stretch (the ratio of the actual job completion time over the minimum job completion time) over all jobs. This approach requires advance knowledge of all job sizes, which may not be available.…”

A delay bounded approach for streaming services in CDMA cellular networks

“…The size of each request (e.g., file length of an HTTP request) is assumed to be known a priori. However, in contrast to our work here, channel conditions in [5] are assumed to be time-invariant during the entire period of serving any single request.…”

“…The following highlights some related results. In [5], the authors evaluate the performance of various scheduling algorithms for serving user requests on the downlink. The size of each request (e.g., file length of an HTTP request) is assumed to be known a priori.…”

Downlink Throughput Maximization in CDMA Wireless Networks

“…The common objective in these studies is either to maximize the sum of rates (or utility), or to minimize the total transmit power, subject to constraints on individual transmit power assignments, total bandwidth, the quality of reception in terms of SINR targets, minimum service requirement of each user (fairness), or delay. For the CDMA downlink, resource allocation problems are studied in [7][8][9][10][11][12][13][14]. A hierarchical SIR and rate control algorithm is proposed in [7].…”