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802.16 networks was conducted in [47,66] by combining link-layer queueing with physical-
layer transmission. A vacation queueing model was adopted in [67] to analyze the link-
layer queueing performance of OFDM-TDMA systems with round-robin scheduling. A
queueing model for OFDMA systems was used in [82] to design a scheduling scheme that
balances multiuser diversity and queueing delay.
Although the packet-level analysis has been conducted for OFDM-TDMA or OFDMA
in [47, 66, 67, 82], there are a few open issues to be addressed. We discuss these issues
and point out our contributions below. First, an analytical framework to account for
both OFDM-TDMA and OFDMA systems to facilitate their comparison is missing. By
generalizing results in [23, 24], we propose a framework to achieve this goal here. Sec-
ond, performance evaluation of 802.16 has been conducted primarily by simulation in the
past, e.g., [41, 53]. We conduct an analysis to demonstrate that OFDMA outperforms
OFDM-TDMA in terms of several QoS metrics. This is consistent with the trend of the
latest IEEE Standard 802.16e-2005 [2], which adopts OFDMA as its principal multiaccess
scheme. Third, although packet average delay and maximum delay are useful link-layer
performance measures for non-real-time (e.g., le transfer and web browsing) and real-
time (e.g., voice and video) applications, respectively, most previous work has focused on
the packet average delay. The packet maximum delay and the delay violation probability
will be examined in this work. Finally, the performance of two well-known scheduling
strategies, namely, the round-robin scheduling and the opportunistic scheduling, is exam-
ined for OFDM-TDMA and OFDMA networks so as to understand their pros and cons
in the context of QoS provisioning.
41
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 55 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 802.16 networks was conducted in [47,66] by combining link-layer queueing with physical- layer transmission. A vacation queueing model was adopted in [67] to analyze the link- layer queueing performance of OFDM-TDMA systems with round-robin scheduling. A queueing model for OFDMA systems was used in [82] to design a scheduling scheme that balances multiuser diversity and queueing delay. Although the packet-level analysis has been conducted for OFDM-TDMA or OFDMA in [47, 66, 67, 82], there are a few open issues to be addressed. We discuss these issues and point out our contributions below. First, an analytical framework to account for both OFDM-TDMA and OFDMA systems to facilitate their comparison is missing. By generalizing results in [23, 24], we propose a framework to achieve this goal here. Sec- ond, performance evaluation of 802.16 has been conducted primarily by simulation in the past, e.g., [41, 53]. We conduct an analysis to demonstrate that OFDMA outperforms OFDM-TDMA in terms of several QoS metrics. This is consistent with the trend of the latest IEEE Standard 802.16e-2005 [2], which adopts OFDMA as its principal multiaccess scheme. Third, although packet average delay and maximum delay are useful link-layer performance measures for non-real-time (e.g., le transfer and web browsing) and real- time (e.g., voice and video) applications, respectively, most previous work has focused on the packet average delay. The packet maximum delay and the delay violation probability will be examined in this work. Finally, the performance of two well-known scheduling strategies, namely, the round-robin scheduling and the opportunistic scheduling, is exam- ined for OFDM-TDMA and OFDMA networks so as to understand their pros and cons in the context of QoS provisioning. 41 |
