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Interference management has been a focus of discussion in the industry. Many
proposals were presented in the standardization meetings with an objective of en-
hancing the e cacy of the next-generation cellular deployment. Most of these
endeavors aim at developing systematic approaches and policies as guidelines for
resource allocation. Notable proposals include inter-cell interference coordination
(ICIC) [35], which suggests allocating disjoint channel resources to cell-edge MSs
that belong to di erent cells; and base station cooperation (BSC) [98], which allows
multiple BSs to transmit coherent signals to multiple MSs concurrently, thereby
turning interference signals to useful ones. Similar mechanisms were suggested for
the multi-cell scenario in 3GPP [8, 9]. Recently, new improvements were proposed
in 3GPP LTE (e.g., [74, 75]) and IEEE 802.16m (e.g., [43]). Most research work
has concentrated on presenting the design concept of ICIC and/or BSC, justifying
the use of these techniques, and obtaining the achievable performance bound.
Graph Approach to Resource Allocation
The channel assignment problem in cellular and mesh networks has been studied in
the context of multi-coloring of a graph for decades [28, 63, 65]. In the traditional
formulation, a graph is constructed and each node in the graph corresponds to a
BS or an access point (AP) in the network to which channels are assigned. The
edge connecting two nodes represents the potential co-channel interference between
these two BSs or APs, which implies their geographical proximity. Then, the chan-
nel assignment problem becomes the node coloring problem, where two interfering
nodes should not have the same color (i.e., using the same channel).
10
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 24 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Interference management has been a focus of discussion in the industry. Many proposals were presented in the standardization meetings with an objective of en- hancing the e cacy of the next-generation cellular deployment. Most of these endeavors aim at developing systematic approaches and policies as guidelines for resource allocation. Notable proposals include inter-cell interference coordination (ICIC) [35], which suggests allocating disjoint channel resources to cell-edge MSs that belong to di erent cells; and base station cooperation (BSC) [98], which allows multiple BSs to transmit coherent signals to multiple MSs concurrently, thereby turning interference signals to useful ones. Similar mechanisms were suggested for the multi-cell scenario in 3GPP [8, 9]. Recently, new improvements were proposed in 3GPP LTE (e.g., [74, 75]) and IEEE 802.16m (e.g., [43]). Most research work has concentrated on presenting the design concept of ICIC and/or BSC, justifying the use of these techniques, and obtaining the achievable performance bound. Graph Approach to Resource Allocation The channel assignment problem in cellular and mesh networks has been studied in the context of multi-coloring of a graph for decades [28, 63, 65]. In the traditional formulation, a graph is constructed and each node in the graph corresponds to a BS or an access point (AP) in the network to which channels are assigned. The edge connecting two nodes represents the potential co-channel interference between these two BSs or APs, which implies their geographical proximity. Then, the chan- nel assignment problem becomes the node coloring problem, where two interfering nodes should not have the same color (i.e., using the same channel). 10 |
