Iterative Signal Processing for Mitigation of Analog-to-Digital Converter Clipping Distortion in Multiband OFDMA Receivers

Algorithm 2

Key steps of the proposed receiver clipping compensation algorithm for Receiver B.

Initialization: for all 𝑘∈Ω_𝐴

(1) Set 𝑖=0,𝛼¹⁽⁰⁾=1and𝑍^𝑘(0)=0

(2) Obtain channel estimates 𝐻^𝑘(𝑖) using signal

   𝑌^𝑘(𝑖)=(1/𝛼^1(𝑖))(𝑌_𝑘−𝑍^𝑘(𝑖))

  (3) Channel equalization: 𝑌^𝑘(𝑖)/𝐻^𝑘(𝑖)

Iteration: Increase 𝑖 by one and do the following steps for all

   𝑘∈Ω_𝐴

  (4) Detect 𝑌^{𝑘(𝑖−1)}/𝐻^{𝑘(𝑖−1)} to obtain symbols 𝑋^𝑘(𝑖)

(5) Estimate clipping levels 𝛾̂_𝐼(𝑖) and 𝛾̂_𝑄(𝑖) as well as

   attenuation factor 𝛼^1(𝑖)

  (6) Clip 𝐻^{𝑘(𝑖−1)}𝑋^𝑘(𝑖) according to 𝛾̂_𝐼(𝑖) and 𝛾̂_𝑄(𝑖) in time

   domain to produce 𝑌^𝑘(𝑖)

(7) Calculate clipping distortion estimate

   𝑍^𝑘(𝑖)=𝑌^𝑘(𝑖)−𝛼^1(𝑖)𝐻^{𝑘(𝑖−1)}𝑋^𝑘(𝑖)

  (8) Remove the distortion from the received signal, that is,

   𝑌^𝑘(𝑖)=(1/𝛼^1(𝑖))(𝑌_𝑘−𝑍^𝑘(𝑖))

  (9) Obtain new channel estimates 𝐻^𝑘(𝑖) using signal 𝑌^𝑘(𝑖)

  (10) Channel equalization: 𝑌^𝑘(𝑖)/𝐻^𝑘(𝑖)

After iteration:

  (11) Demap symbols 𝑌^𝑘(𝑖)/𝐻^𝑘(𝑖) to bits, deinterleave and

   decode to obtain output data bits 𝐛̂^(𝑖)