[논문]An OFDMA-Based Next-Generation Wireless Downlink System Design with Hybrid Multiple Access and Frequency Grouping Techniques

Lee Won-Ick; Lee Byeong Gi; Lee Kwang Bok; Bahk Saewoong

doi:10.1109/jcn.2005.6387859

An OFDMA-Based Next-Generation Wireless Downlink System Design with Hybrid Multiple Access and Frequency Grouping Techniques 원문보기

Journal of communications and networks, v.7 no.2, 2005년, pp.115 - 125

Lee Won-Ick (School of Electrical, Seoul National University) , Lee Byeong Gi (School of Electrical, Seoul National University) , Lee Kwang Bok (School of Electrical, Seoul National University) , Bahk Saewoong (School of Electrical, Seoul National University)

Abstract ▼ AI-Helper

This paper discusses how to effectively design a next-generation wireless communication system that can possibly provide very high data-rate transmissions and versatile quality services. In order to accommodate the sophisticated user requirements and diversified user environments of the next-generation systems, it should be designed to take an efficient and flexible structure for multiple access and resource allocation. In addition, the design should be optimized for cost-effective usage of resources and for efficient operation in a multi-cell environment. As orthogonal frequency division multiple access (OFDMA) has turned out in recent researches to be one of the most promising multiple access techniques that can possibly meet all those requirements through efficient radio spectrum utilization, we take OFDMA as the basic framework in the next-generation wireless communications system design. So, in this paper, we focus on introducing an OFDMA-based downlink system design that employs the techniques of hybrid multiple access (HMA) and frequency group (FG) in conjunction with intra-frequency group averaging (IFGA). The HMA technique combines various multiple access schemes on the basis of OFDMA system, adopting the multiple access scheme that best fits to the given user condition in terms of mobility, service, and environment. The FG concept and IFGA technique help to reduce the feedback overhead of OFDMA system and the other-cell interference (OCI) problem by grouping the sub-carriers based on coherence band-widths and by harmonizing the channel condition and OCI of the grouped sub-carriers.

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가설 설정

Fourth, the system should be capable of overcoming other-cell interference (OCI) caused by universal frequency reuse and be required to minimize the level of coordination among the neighboring cells. Fifth, the architecture should be designed to render an easy connection and/or expansion to IP networks.

제안 방법

We used QPSK, 16-QAM, and 64-QAM for modulation schemes and rate 1/2 convolutional code with length 7 for channel coding. During the simulation, we applied equal power allocation and adapted the modulation set for each sub-carrier through the adaptive sub-carrier allocation (ASA) and adaptive bit allocation (ABA) algorithms [17] in order to minimize the BER with the constraint of the total rate. We do not adapt the code rate in order to reduce the simulation complexity.
of OFDMA. Focusing on the downlink system design, we detailed the reasoning for adopting the HMA framework and the frame structure in connection with the concept of FG and IFGA techniques. The resulting downlink system is therefore tailored for accommodating various user requirements in diverse environments, with flexible adaptation of multiple access schemes and resource management strategies.
of IFGH and IFGS. For the simulations we took the 7-cell environment composed of the target cell and its six first-tier neighbors. We assumed that each cell uses 2, 048 sub'Carriers in a 20 MHz band at a 2 GHz frequency and the symbol length is 115.
However, this is too small a value for practical use and the reduction of feedback and pilot overheads is not large enough. Noting that, the objective of adopting the FG concept is to reduce the overhead of the D'OFDMA or the S-OFDMA channel used by nomadic users, we may exclude from consideration the models for mobile users such as vehicular model of ITU and the case 3, 5, 6, and 7 models of 3GPP. In addition, we may also exclude the hilly terrain model of COST259 by assuming that the users under this model can be serviced by the FH-OFDMA channel.

대상 데이터

3 shows the simulated performance of the adaptive OFDMA for nomadic users with various different delay spreads and FG sizes. For the simulations we assumed an OFDMA system with 2, 048 sub-carriers in a 20 MHz band at a 2 GHz frequency and a 115.2 μ, s symbol length including a 12.8 /is cyclic prefix (CP). We used a 5-path Rayleigh fading channel with exponential decaying delay profile and used five RMS delay spread values of 0.
1 shows the simulated performances of FH-OFDMA and adaptive OFDMA3 techniques with respect to various mobility speeds. The simulation was performed over an OFDM system with 256 sub-carriers in a 2.5 MHz bandwidth and a 115.2 /is symbol length (including cyclic prefix length of 12.8 口s). We assumed that the frame length is 18 OFDM symbols (i.

이론/모형

As there exist multiple S-OFDMA channels and multiple users, it is necessary to group users to share the same S-OFDMA channel by considering the service requirements and environment. In the proposed HMA framework, we dynamically assign up to eight users into an S-OFDMA channel and adopt the CDF-based scheduling (CS) algorithm [12] for opportunistic scheduling. When a new user requests an NRT service, we select an appropriate existing S-OFDMA channel or a new S-OFDMA channel depending whether or not the assignment of the new user violates the QoS requirement of the readily admitted users.

참고문헌 (20)

lTU, 'Report of eighth meeting of ITU-R working party 8F,' Ottawa, Japan, May-June 2002
R. Nee and R. Prasad, OFDM for Wireless Multimedia Communications, Artech House, 2000
H. Rohling and R. Funeid, 'Performance comparison of different multiple access schemes for the downlink of an OFDM communications system,' in Proc. IEEE VTC'97, 1997
H. Sari, 'Orthogonal frequency division multiple access with frequency hopping and diversity,' in Proc. Inter. Workshop Multi-Carrier Spread-Spectrum (MC-SS), 1997
R. Laroia, J. Li, and M. D. Vanderveen, 'Orthogonal frequency divi￢sion multiplexing based spread spectrium multiple access,' US Patents no. 6,473,418 B1, Oct. 2002
S. Hara and R. Prasad, 'Design and performance of multicarrier CDMA system in frequency-selective Rayleigh fading channels,' IEEE Trans. Veh. Technol., vol. 48, no. 5, 1999

상세보기
H. Atarashi, S. Abeta, and M. Sawahashi, 'Variable spreading factor-orthogonal frequency and code division multiplexing (VSF-OFCDM) for broadband packet wireless access,' IEICE Trans. Commun., vol. E86-B, no. 1, 2003
S. Kaiser, 'MC-FDMA and MC-TDMA versus MC-CDMA and SS-MC-MA: Performance evaluation for fading channels,' in Proc. IEEE ISSSTA '98, 1998
A. Jalali, R. Padovani, and R. Pankaj, 'Data throughput of CDMA-HDR a high efficiency-high data rate personal communication wireless system,' in Proc. IEEE VTC 2000, 2000
X. Liu, E. K. P. Chong, and N. B. Shroff, 'Opportunistic transmission scheduling with resource-sharing constraints in wireless networks,' IEEE J. Select. Areas Commun., vol. 19, no. 10, 2001
S. Borst and P. Whiting, 'Dynamic rate control algorithms for HDR throughput optimization,' in Proc. IEEE INFOCOM 2001, 2001
D. Park et aI., 'A new wireless packet scheduling algorithm based on the CDF of user transmission rates,' in Proc. IEEE GLOBECOM 2003, 2003
X. Liu, E. K. P. Chong, and N. B. Shroff, 'A framework for opportunistic scheduling in wireless networks,' Computer Networks, vol. 41, 2003
C. Y. Wong et al., 'OFDMA with adaptive subcarrier, bit, and power allocation,' IEEE J. Select. Areas Commun., vol. 17, no. 10, 1999

상세보기
W. Rhee and J. M. Cioffi, 'Increase in capacity of OFDMA system using dynamic subchannel allocation,' in Proc. IEEE VTC 2000 Spring, 2000
D. Kivanc, G. Li, and H. Liu, 'Computationally efficient bandwidth allo￢'cation and power control for OFDMA,' IEEE Trans. Wireless Commun., vol. 2, no. 6, 2003
H. S. Kim et aI., 'Efficient subcarrier and bit allocation algorithm for OFDMA system with adaptive modulation,' in Proc. IEEE VTC 2004 Spring, 2004
O. Edfors et aI., 'OFDM channel estimation by singular value decomposition,' in Proc. IEEE VTC'96 Spring, 1996
S. Kallel and D. Haccoun, 'Generalized type II hybrid ARQ scheme using punctured convolutional coding,' IEEE Trans. Commun., vol. 38, no. 11, 1990
A. J. Paulraj et aI., 'An Overview of MIMO Communications - a key to gigabit wireless,' Proc. IEEE, vol. 92, no. 2, 2004

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