Broadband packet wireless access appropriate for high-speed and high-capacity throughput

Atarashi, Hiroyuki; Abeta, Sadayuki; Sawahashi, Mamoru

doi:10.1109/vetecs.2001.944906

Cited by 88 publications

(29 citation statements)

References 6 publications

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“…Shah et al [6] compare the performance of OFCDM and OFDM systems as an application in 4G systems. Nippon telegraph and telephone (NTT) DoCoMo has built a 4G prototype system using OFCDM which has achieved 5 Gbit/s over a bandwidth of 100 MHz [7,8].…”

Section: Introductionmentioning

confidence: 99%

Two‐dimensional spreading scheme employing 2D orthogonal variable spreading factor codes for orthogonal frequency and code division multiplexing systems

Puri

Singh

2013

IET Communications

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Future 4G systems require transmission of richer multimedia services which inevitably implies an increase in data rate. Orthogonal frequency and code division multiplexing (OFCDM) technique has shown promising results in achieving a high data rate while simultaneously combating multipath fading. OFCDM is an amalgamation of orthogonal frequency division multiplexing and two-dimensional (2D) spreading. 2D spreading helps to achieve diversity gains in both time and frequency domains. The present OFCDM systems employ 1D orthogonal variable spreading factor (OVSF) codes to achieve the required 2D spreading in code multiplexed channels. However, 2D OVSF codes have better correlation properties in comparison to 1D OVSF codes. Motivated by this principle, the authors propose a spreading scheme for OFCDM systems using 2D OVSF codes. The spreading scheme is designed to increase the system throughput and reduce multi-code interference. Here, the authors study the OFCDM system performance using the proposed spreading scheme in a multipath fast fading channel with varying spreading factors in both time and frequency domains. The results are compared with the existing OFCDM systems using 1D OVSF codes.

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Section: Introductionmentioning

confidence: 99%

Two‐dimensional spreading scheme employing 2D orthogonal variable spreading factor codes for orthogonal frequency and code division multiplexing systems

Puri

Singh

2013

IET Communications

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“…In 3GPP [1], as the data rate increases in 4G by using a broadband channel, NTT-DoCoMo has proposed the Orthogonal Frequency and Code Division Multiplexing (OFCDM) [2]- [4] to satisfy bandwidth requests in future mobile communications. Based on the air interfaces of Multi-carrier CDMA (MC-CDMA) [5] and the Orthogonal Frequency Division Multiplexing (OFDM) [6], OFCDM can operate at a broadband channel with approximate 100 MHz, and supports the data rate ranging from 100Mbps to 5GMbps.…”

Section: Introductionmentioning

confidence: 99%

MDP-Based CAC for Two-Dimension Spreading VSF-OFCDM in 4G Cellular Communications

Chang

Liang

et al. 2009

GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference

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The VSF-OFCDM system has been proposed as the forward link interface for achieving high data rate in 4G mobile communications, which allocates orthogonal channelization codes of an OVSF code tree in two-dimension (2D) spreading in the time and frequency domains. However, it suffers from two disadvantages namely moderate utilization and low transmission quality. Moderate utilization is caused by code blocking, and low transmission quality is due to the multicode interference from high channel loading in the time domain of the 2D spreading. A trade-off thus exists between code blocking and multicode interference. Lower code blocking means higher interference. For achieving high utilization while also providing high transmission quality is a critical issue that should be addressed in 4G VSF-OFCDM. Therefore, this paper proposes a 2D spreading approach based on Adaptive Load-balancing with Markov decision process (denoted by ALM). The ALM approach consists of three phases: 1) the adaptive 2D spreading phase to select the 2D spreading combinations, 2) a dynamic re-combination of a 2D spreading to decrease channel load while supporting transmission quality, and 3) the cost-based Markov decision process (MDP) code selection approach to minimize code blocking and to select the least cost channelization code as the optimal solution. Numerical results indicate that the proposed approach outperforms other approaches in transmission quality ratio and fractional reward loss.

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“…Multiple-input and multiple-output (MIMO) [1] multiplexing is widely taken as an effective technique to provide high speed transmissions. On the other hand, combining OFDM with two-dimensional (2-D) spreading [2], an orthogonal frequency and code division multiplexing (OFCDM) [3] system has been proposed as a promising wireless access technique for the downlink transmission in future wireless communications. Based on OFDM, OFCDM can combat the severe multipath interference in a broadband channel.…”

Section: Introductionmentioning

confidence: 99%

Joint Iterative Detection for Multi-Code MIMO-OFCDM Systems

Zhou¹

2008

2008 4th IEEE International Conference on Circuits and Systems for Communications

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This paper investigates a two-dimensionally spread orthogonal frequency and code division multiplexing (OFCDM) system with multi-code transmission and multiple input multiple output (MIMO) multiplexing, where desired data signals are interfered by not only co-channel signals from other transmit antennas (or multi-antenna interference (MAI)), but also multicode interference (MCI) from other code channels on the same antenna. Combining the iterative detection in the space domain and the hybrid MCI cancellation and minimum mean square error (MMSE) detection in the frequency domain, a joint iterative detection algorithm is proposed to cancel out MAI and MCI. For the 0 th loop of the joint iterative detection, a 2-stage hybrid detection is needed in the frequency domain, while for later loops, a 0-stage hybrid detection or pure MMSE is sufficient. The system performance improves as the number of loops in the joint iterative detection increases. Moreover, using joint iterative detection, larger frequency diversity gain can be achieved and the performance improves as the frequency domain spreading factor increases.

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Broadband packet wireless access appropriate for high-speed and high-capacity throughput

Cited by 88 publications

References 6 publications

Two‐dimensional spreading scheme employing 2D orthogonal variable spreading factor codes for orthogonal frequency and code division multiplexing systems

Two‐dimensional spreading scheme employing 2D orthogonal variable spreading factor codes for orthogonal frequency and code division multiplexing systems

MDP-Based CAC for Two-Dimension Spreading VSF-OFCDM in 4G Cellular Communications

Joint Iterative Detection for Multi-Code MIMO-OFCDM Systems

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