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In the third part of the dissertation, we propose a high-performance yet low-complexity
multi-cell OFDMA downlink resource allocation method to enable interference manage-
ment techniques such as ICIC and BSC. Related previous work is reviewed in the follow-
ing.
Multi-Cell OFDMA Resource Allocation
The multi-cell resource allocation problem can be dealt with by extending the single-
cell allocation idea to the multi-cell scenario. This may be done, for instance, by
considering the signal-to-interference-and-noise ratio (SINR) instead of the signal-
to-noise ratio (SNR) in the problem formulation. This formulation is attractive since
most of single-cell OFDMA resource allocation schemes can be directly applied to
the multi-cell context. For instance, Li and Liu [60] proposed a two-level resource
allocation scheme, wherein the radio network controller (RNC) coordinates multiple
cells in the rst level, and performs per-cell optimization in the second level. The
rst level is conducted based on perfect and predetermined knowledge of SINR
for all MSs on all subchannels. A similar approach was adopted in [40] with some
special treatment on ICI. Pietrzyk and Janssen [69,70] proposed heuristic algorithms
for their formulated problems based on SINR, with some quality-of-service (QoS)
consideration. A key assumption in this group of research work is the availability
of SINR, which is however di cult to obtain a priori due to mutual dependency of
ICI. In other words, a multi-cell resource allocation scheme contingent upon global
and perfect knowledge of SINR is not practical.
Interference Management
9
Object Description
| Title | Resource allocation in OFDM/OFDMA cellular networks: protocol design and performance analysis |
| Author | Chang, Yu-Jung |
| Author email | yujungc@usc.edu; yjrchang@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Electrical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2008-09-09 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-29 |
| Advisor (committee chair) | Kuo, C.-C. Jay |
| Advisor (committee member) |
Neely, Michael J. Govindan, Ramesh |
| Abstract | Orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA) are two promising technologies adopted in the IEEE 802.16 standard to support broadband wireless access as well as multimedia quality-of-service (QoS). In this dissertation, we discuss several important topics regarding OFDM/OFDMA: cross-layer performance analysis of OFDM and OFDMA downlinks in terms of several QoS metrics; the medium access control (MAC) protocol design for the OFDMA uplink; and the inter-cell interference (ICI) management in multi-cell OFDMA networks through a systematic approach.; First, performance analysis of OFDM-TDMA and OFDMA networks is performed in terms of cross-layer QoS measures which include the bit rate and the bit error rate (BER) in the physical layer, and packet average throughput/delay and packet maximum delay in the link layer. We adopt a cross-layer QoS framework similar to that in IEEE 802.16, where service classification, flow control and opportunistic scheduling with different subcarrier/bit allocation schemes are implemented. Our analysis provides important insights into the performance differences of these two multiaccess systems. In addition, it is shown by analysis and simulation that OFDMA outperforms OFDM-TDMA in QoS metrics of interest. Thus, we conclude that OFDMA has higher potential in supporting multimedia services.; Second, a distributed MAC algorithm for uplink OFDMA networks under the IEEE 802.16 framework is proposed and analyzed. We present a simple yet efficient algorithm to enhance the system throughput by integrating opportunistic medium access and collision resolution through random subchannel backoff. Consequently, the resulting algorithm is called the opportunistic access with random subchannel backoff (OARSB) scheme. OARSB not only achieves distributed coordination among users but also reduces the amount of information exchange between the base station and users. The throughput and delay performance analysis of OARSB is conducted, and the superior performance of OARSB over an existing scheme is demonstrated by analysis as well as computer simulation. Besides, the proposed OARSB scheme can be easily implemented in 802.16 due to its simplicity.; Lastly, a practical and low-complexity multi-cell OFDMA downlink channel assignment method using a graphic framework is proposed. Our solution consists of two phases: 1) a coarse-scale inter-cell interference (ICI) management scheme and 2) a fine-scale channel-aware resource allocation scheme. In the first phase, the task of managing the performance-limiting ICI in cellular networks is accomplished by a graphic approach, in which no ICI measurement is needed and state-of-the-art ICI management schemes such as ICI coordination (ICIC) and base station cooperation (BSC) can be incorporated easily. In the second phase, channel assignment is accomplished by taking instantaneous channel conditions into account. Heuristic algorithms are proposed to solve both phases of the problem efficiently. Extensive simulation is conducted for various practical scenarios to demonstrate the superior performance of the proposed solution against the conventional OFDMA allocation scheme. Thanks to its practicality and low complexity, the proposed scheme can be used in next generation cellular systems such as the 3GPP Long Term Evolution (LTE) and IEEE 802.16m. |
| Keyword | OFDM; OFDMA; MAC protocol design; performance analysis; resource allocation; interference management; IEEE 802.16; cellular networks |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1704 |
| Contributing entity | University of Southern California |
| Rights | Chang, Yu-Jung |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Chang-2392 |
| Archival file | uscthesesreloadpub_Volume40/etd-Chang-2392.pdf |
Description
| Title | Page 23 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | In the third part of the dissertation, we propose a high-performance yet low-complexity multi-cell OFDMA downlink resource allocation method to enable interference manage- ment techniques such as ICIC and BSC. Related previous work is reviewed in the follow- ing. Multi-Cell OFDMA Resource Allocation The multi-cell resource allocation problem can be dealt with by extending the single- cell allocation idea to the multi-cell scenario. This may be done, for instance, by considering the signal-to-interference-and-noise ratio (SINR) instead of the signal- to-noise ratio (SNR) in the problem formulation. This formulation is attractive since most of single-cell OFDMA resource allocation schemes can be directly applied to the multi-cell context. For instance, Li and Liu [60] proposed a two-level resource allocation scheme, wherein the radio network controller (RNC) coordinates multiple cells in the rst level, and performs per-cell optimization in the second level. The rst level is conducted based on perfect and predetermined knowledge of SINR for all MSs on all subchannels. A similar approach was adopted in [40] with some special treatment on ICI. Pietrzyk and Janssen [69,70] proposed heuristic algorithms for their formulated problems based on SINR, with some quality-of-service (QoS) consideration. A key assumption in this group of research work is the availability of SINR, which is however di cult to obtain a priori due to mutual dependency of ICI. In other words, a multi-cell resource allocation scheme contingent upon global and perfect knowledge of SINR is not practical. Interference Management 9 |
