Cooperative Scheduling of Downlink Beam Transmissions in a Cellular Network

Abstract

The next generation of wireless networks (e.g., [1]) will use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, beamforming, in the downlink channel. In each sector a number of fixed beams are used to serve users. For each frame the scheduler chooses a beam and then schedules one or more mobiles that lie within that beam. Since the basestation's power is focused on a narrow beam then the served users can achieve higher rates and the sector coverage is also increased. However, this beam causes more interference in adjacent sectors. If a neighboring sector schedules a user that lies within the coverage of the beam then the achievable rate for that user will be low. The neighboring sectors must therefore schedule users outside of the beam. This requires coordination among the sectors. In this paper we assume that each sector coordinates with the sector that lies directly opposite. We provide a framework and show what information needs to be exchanged and how the schedulers in each basestation uses the exchanged information to schedule users so that beam collisions are avoided. This must be done with the objectives of high spectral efficiencies and also user fairness. We compare our approach with a simple, non-coordinated approach to illustrate the advantages that coordination provides.

Multicell Coordination via Joint Scheduling, Beamforming, and Power Spectrum Adaptation

“…For example, the joint design of beamforming across multiple cells has been considered in [25], [26], [27], [28], [29], [30], [31], [32], but these studies typically focus on the minimization of transmit power for a fixed set of selected users, instead of the optimization of network utility. Likewise, intercell scheduling has been considered in [33], [34], [35], [36], [37], [38], and intercell power control has been considered in [39], [40], but these studies do not include beamforming.…”

Semi-Distributed Coordinative Switch Beamforming with Power Scheduling

“…The semi-distributed algorithm proposed in [1] only considers two facing sectors. The scheduling beams in the coordination area are illustrated in Fig.1 The outline of this semi-distributed algorithm is as follow.…”

“…Assume Shadow fading and Loss factor are identical in each sector. The antenna gain of user k , i.e., We compare our proposed algorithm with the existing round robin beam servicing approach [4] and the approach that applies only beam cooperative scheduling [1] in three simulation scenes.…”

“…The next generation of wireless networks will be based on the OFDMA (Orthogonal Frequency Division Multiple Access) radio transmission technology and will use antenna arrays based MIMO (Multi-Input Multioutput) technology to achieve high spectral efficiency [1]. The system will also adopt full frequency reuse among the cells to realize high transmission speed.…”

“…Ref. [1] proposed a semidistributed algorithm, in which each sector can get the optimal beam applied order independently by coordinate transmissions between sectors. In [1] the transmitted powers of all beams are identical.…”