The PhD study will focus on the topic of packet scheduling (PS), in downlink, for the upcoming UTRAN Long Term Evolution (LTE) system. The important features of the LTE system will be support for only packet domain data, peak downlink data rate in the order of 100 Mbps, 2-4x spectral efficiency in comparison to 3G HSDPA, low latency, etc. The air interface will be based on OFDM and MIMO will be an integral part of the system. The packet scheduler functionality becomes critical in this scenario as it will mainly determine system/user performance. The scheduler has a complex task of managing Quality-of-Service (QoS) requests ranging from real-time traffic to best effort delivery, while maintaining high system capacity. In comparison to legacy scheduling algorithms, we will consider packet scheduling in multiple domains, namely, time, frequency, and space. The main objective is to investigate potential of Frequency-Domain Packet Scheduling (FDPS) for the LTE system. In OFDM-type signals adaptation in frequency-domain is known to provide significant improvement in link/system performance, and is commonly known as bit-power loading. Starting from the well known theoretical foundation of such adaptation we will develop algorithms taking into account practical system aspects, such as, limited dynamic range, multi-user multiplexing, amount of signaling overhead, adaptation uncertainties, reasonable convergence and complexity, etc. The investigations will mostly be based on computer simulations. A detailed link and system-level modeling framework will be developed for this purpose. The study will cover a wide range of scenarios including, single-user optimization, multi-user multiplexing, impact of speed, environment and QoS on algorithm performance. In summary, the main topics of research are Frequency-Domain Link Adaptation (FDLA) (i.e., single-user optimization), fast radio-channel aware packet scheduling in frequency-domain (FDPS) (i.e., multi-user case), cross-layer optimization (interplay between QoS parameters, AMC and HARQ) and investigation of signaling overhead requirements. (Akhilesh Pokhariyal, Preben E. Mogensen, Troels E. Kolding, Troels B. Sørensen, Nokia)
|Effektiv start/slut dato
|01/09/2004 → 31/12/2007
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