TY - JOUR

T1 - On cubic metric reduction in OFDM systems by tone reservation

AU - Deumal, Marc

AU - Behravan, Ali

AU - Pijoan, Joan Lluís

PY - 2011/6

Y1 - 2011/6

N2 - One of the major drawbacks of multicarrier modulation is the large envelope fluctuations which either requires an inefficient use of high power amplifiers (HPAs) or decreases the system performance. Peak-to-average power ratio (PAPR) is the best known measure of the envelope fluctuations and is widely employed to design multicarrier systems. However, recently, another metric known as cubic metric (CM), is being considered in several multicarrier systems since it can predict HPA power de-rating more accurately. In this paper tone reservation (TR) technique, originally used for PAPR-reduction, is reformulated to reduce CM. We first simplify CM to define the objective function, denoted as objective CM (OCM). Then we demonstrate that OCM is convex and formulate TR for CM-reduction as an unconstrained convex optimization problem. The solution to this problem is found by means of an iterative algorithm which approaches the optimal solution with few steps. In this paper a low-complexity suboptimal algorithm capable of approaching the optimum with sufficient accuracy is also proposed. Simulation results show that for similar computational complexity, the performance of CM-reduction is superior to that of PAPR-reduction both in terms of bit error rate and out-of-band leakage.

AB - One of the major drawbacks of multicarrier modulation is the large envelope fluctuations which either requires an inefficient use of high power amplifiers (HPAs) or decreases the system performance. Peak-to-average power ratio (PAPR) is the best known measure of the envelope fluctuations and is widely employed to design multicarrier systems. However, recently, another metric known as cubic metric (CM), is being considered in several multicarrier systems since it can predict HPA power de-rating more accurately. In this paper tone reservation (TR) technique, originally used for PAPR-reduction, is reformulated to reduce CM. We first simplify CM to define the objective function, denoted as objective CM (OCM). Then we demonstrate that OCM is convex and formulate TR for CM-reduction as an unconstrained convex optimization problem. The solution to this problem is found by means of an iterative algorithm which approaches the optimal solution with few steps. In this paper a low-complexity suboptimal algorithm capable of approaching the optimum with sufficient accuracy is also proposed. Simulation results show that for similar computational complexity, the performance of CM-reduction is superior to that of PAPR-reduction both in terms of bit error rate and out-of-band leakage.

KW - Orthogonal frequency division multiplexing (OFDM)

KW - cubic metric (CM)

KW - nonlinear distortion

KW - peak-to-average power ratio (PAPR)

UR - http://www.scopus.com/inward/record.url?scp=79959536891&partnerID=8YFLogxK

U2 - 10.1109/TCOMM.2011.042111.070613

DO - 10.1109/TCOMM.2011.042111.070613

M3 - Article

AN - SCOPUS:79959536891

SN - 0090-6778

VL - 59

SP - 1612

EP - 1620

JO - IEEE Transactions on Communications

JF - IEEE Transactions on Communications

IS - 6

M1 - 5756418

ER -