Uplink Access Schemes for LTE-Advanced

Le LIU  Takamichi INOUE  Kenji KOYANAGI  Yoshikazu KAKURA  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.5   pp.1760-1768
Publication Date: 2009/05/01
Online ISSN: 1745-1345
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Radio Access Techniques for 3G Evolution)
LTE-Advanced,  DFT-spread-OFDM,  SC-FDMA,  OFDM,  discontinuous resource allocation,  

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The 3GPP LTE-Advanced has been attracting much attention recently, where the channel bandwidth would be beyond the maximum bandwidth of LTE, 20 MHz. In LTE, single carrier-frequency division multiple access (SC-FDMA) was accepted as the uplink access scheme due to its advantage of very low cubic metric (CM). For LTE-A wideband transmission, multicarrier access would be more effective than single carrier access to make use of multi-user diversity and can maintain the physical channel structure of LTE, where the control information is transmitted on the edges of each 20 MHz. In this paper, we discuss the access schemes in bandwidth under 20 MHz as well as over 20 MHz. In the case of bandwidth under 20 MHz, we propose the access schemes allowing discontinuous resource allocation to enhance average throughput while maintaining cell-edge user throughput, that is, DFT-spread-OFDM with spectrum division control (SDC) and adaptive selection of SC-FDMA and OFDM (SC+OFDM). The number of discontinuous spectrums is denoted as spectrum division (SD). For DFT-S-OFDM, we define a parameter max SD as the upper limit of SD. We evaluate our proposed schemes in bandwidth under 20 MHz and find that SC+OFDM as well as SDC with common max SD or UE-specific max SD can improve average throughput while their cell-edge user throughput can approach that of SC-FDMA. In the case of bandwidth over 20 MHz, we consider key factors to decide a feasible access scheme for aggregating several 20 MHz-wide bands.