Utilization of null subcarriers for PAPR reduction in 3GPP LTE downlink

Cho, Soobum; Park, Soo Young; Kwon, Du Jin

doi:10.1109/icnidc.2012.6418710

Cited by 1 publication

(2 citation statements)

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“…Firstly, the number of null subcarriers per frame, N spaces,1×1 FRM , is calculated in the physical downlink shared channel (PDSCH) of the LTE SISO system [ 17 ]. The number of data per RB, N data,1×1 RB , can be obtained as

where N symb DL is the number of symbols per slot, which is 7 in normal CP, N sc RB is the number of subcarriers per RB, which is 12, N pilot RB is the number of reference signals (RSs) per RB, which is 4, and N u-pilot,1×1 RB is the number of RSs used in other antenna ports per RB, which is 0 in SISO system.…”

Section: Calculation Of the Null Subcarriers Of The Lte Downlink Smentioning

confidence: 99%

“…The number of dummy sequences needed for the desired PAPR reduction level depends on the feature of the communication systems. In [ 17 ], the number of unused subcarriers was calculated in the LTE single-input single-output (SISO) system and it was used for the dummy sequences with cyclic shifted sequences scheme. However, the PAPR reduction performance was still high, since dummy sequences were not optimally scheduled.…”

Section: Introductionmentioning

confidence: 99%

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Optimized Scheduling Technique of Null Subcarriers for Peak Power Control in 3GPP LTE Downlink

Cho

Park

2014

The Scientific World Journal

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Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system.

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