基于FPGA的OFDM-BPSK链路verilog实现,开发平台为quartusii

目录

一、理论基础

二、核心程序

三、测试结果

---

一、理论基础

       OFDM（Orthogonal Frequency Division Multiplexing）和BPSK（Binary Phase Shift Keying）都是数字通信中常用的调制和多路复用技术。在一个OFDM-BPSK链路中，BPSK用于调制数据信号，而OFDM用于多路复用和传输。

1. BPSK调制（Binary Phase Shift Keying）： BPSK是一种基本的调制方式，它将数字比特转换为相位。在BPSK中，一个逻辑0被映射为一个特定相位（通常是0度），而一个逻辑1被映射为相位的反转（通常是180度）。这样，数字数据可以通过改变相位来调制成模拟信号。在接收端，可以通过检测相位来解调信号。

2. OFDM（Orthogonal Frequency Division Multiplexing）： OFDM是一种多载波调制技术，它将高速数据流分成多个低速子载波，这些子载波之间是正交的。每个子载波都可以独立传输信息，从而提高了频谱效率和抗多径干扰的能力。OFDM还使用了循环前缀（Cyclic Prefix）来抵消多径引起的符号间干扰。

         在一个OFDM-BPSK链路中，BPSK调制通常应用于每个子载波上的符号。OFDM将这些BPSK调制的符号组合成一个复杂的OFDM符号，然后进行传输。接收端将OFDM信号进行解调，分离各个子载波上的符号，再进行BPSK解调以还原原始二进制数据。OFDM-BPSK链路是一种强大的通信系统，通过将OFDM和BPSK相结合，可以实现高效的数据传输，抗多径干扰，以及适应不同信道条件的需求。

       设OFDM信号发射时间周期为[0，T]，子载波数为N，N也是符号序列的时间间隔。可以证明满足子载波正交的条件为：=1/T。（式中为子载波的频率间隔。）输入数据流首先被QAM调制器调制，这里其实是完成一个星座点的映射过程，并没有进行频谱搬移。经过星座映射后得到的符号，存在两个相互正交的分量和。设。所以再进行OFDM调制进行频谱搬移后，已调信号的数学表达式为：

 

       由上式可知，恰好是的逆离散傅里叶变换（IDFT）。所以OFDM调制可以由IDFT实现，解调可以由DFT实现。

      对于调制过程，输入数据流首先被QAM调制器调制，这里其实是完成一个星座点的映射过程，并没有进行频谱搬移。得到了一个复符号流d[0]，d[1]，…，d[N-1]，复符号流通过串/并变换，得到一系列并行的QAM符号d[0]，d[1]，…，d[N-1]。经过IFFT变换，得到一系列并行的符号流，，…，，再将它们经过并/串变换，得到一串串行的符号流，，…，。由于此时符号流为离散的，所以要经过D/A转换，将其变为时间上连续的信号。最后再将信号搬移到射频。解调过程正好相反。

        应此我们设计的数字系统是一个OFDM 通信系统中的基带数据处理部分，就是不包括变频，射频电路部分的设计，甚至没有加入同步的部分，而是只包括信道编码、交织、星座映射、FFT 和插入循环前缀的部分。。下面叙述一下发射和接收端的具体结构。

二、核心程序

`timescale 1 ns / 1 ps
 
module FFT_s2p(
               i_clk,
					i_rst,
					i_I,
					i_Q,
					o_flag,
					o_dout1,
					o_dout2,
					o_dout0,
					test1,
					test2
              );
 
input  i_clk;
input  i_rst;
input signed[7:0]i_I;
input signed[7:0]i_Q;
output    		  o_flag;	  
output     [31:0]o_dout1;				  
output     [31:0]o_dout2;	
output     [31:0]o_dout0;					  
output signed[7:0]test1;
output signed[7:0]test2;				  
				  
reg signed[7:0]rt1,it1;
reg signed[7:0]rt2,it2;
reg signed[7:0]rt3,it3;
reg signed[7:0]rt4,it4;
reg signed[7:0]rt5,it5;
reg signed[7:0]rt6,it6;
reg signed[7:0]rt7,it7;
reg signed[7:0]rt8,it8;
reg signed[7:0]rt9,it9;
reg signed[7:0]rt10,it10;
reg signed[7:0]rt11,it11;
reg signed[7:0]rt12,it12;
reg signed[7:0]rt13,it13;
reg signed[7:0]rt14,it14;
reg signed[7:0]rt15,it15;
reg signed[7:0]rt16,it16;
reg signed[7:0]rt17,it17;
reg signed[7:0]rt18,it18;
reg signed[7:0]rt19,it19;
reg signed[7:0]rt20,it20;
reg signed[7:0]rt21,it21;
reg signed[7:0]rt22,it22;
reg signed[7:0]rt23,it23;
reg signed[7:0]rt24,it24;
reg signed[7:0]rt25,it25;
reg signed[7:0]rt26,it26;
reg signed[7:0]rt27,it27;
reg signed[7:0]rt28,it28;
reg signed[7:0]rt29,it29;
reg signed[7:0]rt30,it30;
reg signed[7:0]rt31,it31;
reg signed[7:0]rt32,it32;
reg signed[7:0]r1,i1;
reg signed[7:0]r2,i2;
reg signed[7:0]r3,i3;
reg signed[7:0]r4,i4;
reg signed[7:0]r5,i5;
reg signed[7:0]r6,i6;
reg signed[7:0]r7,i7;
reg signed[7:0]r8,i8;
reg signed[7:0]r9,i9;
reg signed[7:0]r10,i10;
reg signed[7:0]r11,i11;
reg signed[7:0]r12,i12;
reg signed[7:0]r13,i13;
reg signed[7:0]r14,i14;
reg signed[7:0]r15,i15;
reg signed[7:0]r16,i16;
reg signed[7:0]r17,i17;
reg signed[7:0]r18,i18;
reg signed[7:0]r19,i19;
reg signed[7:0]r20,i20;
reg signed[7:0]r21,i21;
reg signed[7:0]r22,i22;
reg signed[7:0]r23,i23;
reg signed[7:0]r24,i24;
reg signed[7:0]r25,i25;
reg signed[7:0]r26,i26;
reg signed[7:0]r27,i27;
reg signed[7:0]r28,i28;
reg signed[7:0]r29,i29;
reg signed[7:0]r30,i30;
reg signed[7:0]r31,i31;
reg signed[7:0]r32,i32;
 
reg[4:0]cnt;
reg      o_flag;
always @(posedge i_clk or posedge i_rst)
begin
     if(i_rst)
	  begin
	  o_flag <= 1'b0;
	  cnt <= 5'd0;
	r1<= 0;i1<= 0;
r2<= 0;i2<= 0;
r3<= 0;i3<= 0;
r4<= 0;i4<= 0;
r5<= 0;i5<= 0;
r6<= 0;i6<= 0;
r7<= 0;i7<= 0;
r8<= 0;i8<= 0;
r9<= 0;i9<= 0;
r10<= 0;i10<= 0;
r11<= 0;i11<= 0;
r12<= 0;i12<= 0;
r13<= 0;i13<= 0;
r14<= 0;i14<= 0;
r15<= 0;i15<= 0;
r16<= 0;i16<= 0;
r17<= 0;i17<= 0;
r18<= 0;i18<= 0;
r19<= 0;i19<= 0;
r20<= 0;i20<= 0;
r21<= 0;i21<= 0;
r22<= 0;i22<= 0;
r23<= 0;i23<= 0;
r24<= 0;i24<= 0;
r25<= 0;i25<= 0;
r26<= 0;i26<= 0;
r27<= 0;i27<= 0;
r28<= 0;i28<= 0;
r29<= 0;i29<= 0;
r30<= 0;i30<= 0;
r31<= 0;i31<= 0;
r32<= 0;i32<= 0;
rt1<= 0;it1<= 0;
rt2<= 0;it2<= 0;
rt3<= 0;it3<= 0;
rt4<= 0;it4<= 0;
rt5<= 0;it5<= 0;
rt6<= 0;it6<= 0;
rt7<= 0;it7<= 0;
rt8<= 0;it8<= 0;
rt9<= 0;it9<= 0;
rt10<= 0;it10<= 0;
rt11<= 0;it11<= 0;
rt12<= 0;it12<= 0;
rt13<= 0;it13<= 0;
rt14<= 0;it14<= 0;
rt15<= 0;it15<= 0;
rt16<= 0;it16<= 0;
rt17<= 0;it17<= 0;
rt18<= 0;it18<= 0;
rt19<= 0;it19<= 0;
rt20<= 0;it20<= 0;
rt21<= 0;it21<= 0;
rt22<= 0;it22<= 0;
rt23<= 0;it23<= 0;
rt24<= 0;it24<= 0;
rt25<= 0;it25<= 0;
rt26<= 0;it26<= 0;
rt27<= 0;it27<= 0;
rt28<= 0;it28<= 0;
rt29<= 0;it29<= 0;
rt30<= 0;it30<= 0;
rt31<= 0;it31<= 0;
rt32<= 0;it32<= 0;	
	  end
else begin
	  cnt <= cnt + 5'd1;
rt1<= i_I;	  
rt2<= rt1;
rt3<= rt2;
rt4<= rt3;
rt5<= rt4;
rt6<= rt5;
rt7<= rt6;
rt8<= rt7;
rt9<= rt8;
rt10<= rt9;
rt11<= rt10;
rt12<= rt11;
rt13<= rt12;
rt14<= rt13;
rt15<= rt14;
rt16<= rt15;
rt17<= rt16;
rt18<= rt17;
rt19<= rt18;
rt20<= rt19;
rt21<= rt20;
rt22<= rt21;
rt23<= rt22;
rt24<= rt23;
rt25<= rt24;
rt26<= rt25;
rt27<= rt26;
rt28<= rt27;
rt29<= rt28;
rt30<= rt29;
rt31<= rt30;
rt32<= rt31;
it1<= i_Q;
it2<= it1;
it3<= it2;
it4<= it3;
it5<= it4;
it6<= it5;
it7<= it6;
it8<= it7;
it9<= it8;
it10<= it9;
it11<= it10;
it12<= it11;
it13<= it12;
it14<= it13;
it15<= it14;
it16<= it15;
it17<= it16;
it18<= it17;
it19<= it18;
it20<= it19;
it21<= it20;
it22<= it21;
it23<= it22;
it24<= it23;
it25<= it24;
it26<= it25;
it27<= it26;
it28<= it27;
it29<= it28;
it30<= it29;
it31<= it30;
it32<= it31;
	  
	  if(cnt == 3)
	  begin
 r1<= rt1;
r2<= rt2;
r3<= rt3;
r4<= rt4;
r5<= rt5;
r6<= rt6;
r7<= rt7;
r8<= rt8;
r9<= rt9;
r10<= rt10;
r11<= rt11;
r12<= rt12;
r13<= rt13;
r14<= rt14;
r15<= rt15;
r16<= rt16;
r17<= rt17;
r18<= rt18;
r19<= rt19;
r20<= rt20;
r21<= rt21;
r22<= rt22;
r23<= rt23;
r24<= rt24;
r25<= rt25;
r26<= rt26;
r27<= rt27;
r28<= rt28;
r29<= rt29;
r30<= rt30;
r31<= rt31;
r32<= rt32;
i1<= it1;
i2<= it2;
i3<= it3;
i4<= it4;
i5<= it5;
i6<= it6;
i7<= it7;
i8<= it8;
i9<= it9;
i10<= it10;
i11<= it11;
i12<= it12;
i13<= it13;
i14<= it14;
i15<= it15;
i16<= it16;
i17<= it17;
i18<= it18;
i19<= it19;
i20<= it20;
i21<= it21;
i22<= it22;
i23<= it23;
i24<= it24;
i25<= it25;
i26<= it26;
i27<= it27;
i28<= it28;
i29<= it29;
i30<= it30;
i31<= it31;
i32<= it32;
	  o_flag <= ~o_flag;
	  end
	  else begin
r1<= r1;
r2<= r2;
r3<= r3;
r4<= r4;
r5<= r5;
r6<= r6;
r7<= r7;
r8<= r8;
r9<= r9;
r10<= r10;
r11<= r11;
r12<= r12;
r13<= r13;
r14<= r14;
r15<= r15;
r16<= r16;
r17<= r17;
r18<= r18;
r19<= r19;
r20<= r20;
r21<= r21;
r22<= r22;
r23<= r23;
r24<= r24;
r25<= r25;
r26<= r26;
r27<= r27;
r28<= r28;
r29<= r29;
r30<= r30;
r31<= r31;
r32<= r32;
i1<= i1;
i2<= i2;
i3<= i3;
i4<= i4;
i5<= i5;
i6<= i6;
i7<= i7;
i8<= i8;
i9<= i9;
i10<= i10;
i11<= i11;
i12<= i12;
i13<= i13;
i14<= i14;
i15<= i15;
i16<= i16;
i17<= i17;
i18<= i18;
i19<= i19;
i20<= i20;
i21<= i21;
i22<= i22;
i23<= i23;
i24<= i24;
i25<= i25;
i26<= i26;
i27<= i27;
i28<= i28;
i29<= i29;
i30<= i30;
i31<= i31;
i32<= i32;
	  o_flag <= o_flag;
	  end
     end
end
wire signed[15:0]rr1,ii1;
wire signed[15:0]rr2,ii2;
wire signed[15:0]rr3,ii3;
wire signed[15:0]rr4,ii4;
wire signed[15:0]rr5,ii5;
wire signed[15:0]rr6,ii6;
wire signed[15:0]rr7,ii7;
wire signed[15:0]rr8,ii8;
wire signed[15:0]rr9,ii9;
wire signed[15:0]rr10,ii10;
wire signed[15:0]rr11,ii11;
wire signed[15:0]rr12,ii12;
wire signed[15:0]rr13,ii13;
wire signed[15:0]rr14,ii14;
wire signed[15:0]rr15,ii15;
wire signed[15:0]rr16,ii16;
wire signed[15:0]rr17,ii17;
wire signed[15:0]rr18,ii18;
wire signed[15:0]rr19,ii19;
wire signed[15:0]rr20,ii20;
wire signed[15:0]rr21,ii21;
wire signed[15:0]rr22,ii22;
wire signed[15:0]rr23,ii23;
wire signed[15:0]rr24,ii24;
wire signed[15:0]rr25,ii25;
wire signed[15:0]rr26,ii26;
wire signed[15:0]rr27,ii27;
wire signed[15:0]rr28,ii28;
wire signed[15:0]rr29,ii29;
wire signed[15:0]rr30,ii30;
wire signed[15:0]rr31,ii31;
wire signed[15:0]rr32,ii32;
assign rr1 = {126*r1}-{25*i1};
assign ii1 = {25*r1}+{126*i1};
assign rr2 = {118*r2}-{49*i2};
assign ii2 = {49*r2}+{118*i2};
assign rr3 = {106*r3}-{71*i3};
assign ii3 = {71*r3}+{106*i3};
assign rr4 = {91*r4}-{91*i4};
assign ii4 = {91*r4}+{91*i4};
assign rr5 = {71*r5}-{106*i5};
assign ii5 = {106*r5}+{71*i5};
assign rr6 = {49*r6}-{118*i6};
assign ii6 = {118*r6}+{49*i6};
assign rr7 = {25*r7}-{126*i7};
assign ii7 = {126*r7}+{25*i7};
assign rr8 = {0*r8}-{128*i8};
assign ii8 = {128*r8}+{0*i8};
assign rr9 = {-25*r9}-{126*i9};
assign ii9 = {126*r9}+{-25*i9};
assign rr10 = {-49*r10}-{118*i10};
assign ii10 = {118*r10}+{-49*i10};
assign rr11 = {-71*r11}-{106*i11};
assign ii11 = {106*r11}+{-71*i11};
assign rr12 = {-91*r12}-{91*i12};
assign ii12 = {91*r12}+{-91*i12};
assign rr13 = {-106*r13}-{71*i13};
assign ii13 = {71*r13}+{-106*i13};
assign rr14 = {-118*r14}-{49*i14};
assign ii14 = {49*r14}+{-118*i14};
assign rr15 = {-126*r15}-{25*i15};
assign ii15 = {25*r15}+{-126*i15};
assign rr16 = {-128*r16}-{0*i16};
assign ii16 = {0*r16}+{-128*i16};
assign rr17 = {-126*r17}-{-25*i17};
assign ii17 = {-25*r17}+{-126*i17};
assign rr18 = {-118*r18}-{-49*i18};
assign ii18 = {-49*r18}+{-118*i18};
assign rr19 = {-106*r19}-{-71*i19};
assign ii19 = {-71*r19}+{-106*i19};
assign rr20 = {-91*r20}-{-91*i20};
assign ii20 = {-91*r20}+{-91*i20};
assign rr21 = {-71*r21}-{-106*i21};
assign ii21 = {-106*r21}+{-71*i21};
assign rr22 = {-49*r22}-{-118*i22};
assign ii22 = {-118*r22}+{-49*i22};
assign rr23 = {-25*r23}-{-126*i23};
assign ii23 = {-126*r23}+{-25*i23};
assign rr24 = {0*r24}-{-128*i24};
assign ii24 = {-128*r24}+{0*i24};
assign rr25 = {25*r25}-{-126*i25};
assign ii25 = {-126*r25}+{25*i25};
assign rr26 = {49*r26}-{-118*i26};
assign ii26 = {-118*r26}+{49*i26};
assign rr27 = {71*r27}-{-106*i27};
assign ii27 = {-106*r27}+{71*i27};
assign rr28 = {91*r28}-{-91*i28};
assign ii28 = {-91*r28}+{91*i28};
assign rr29 = {106*r29}-{-71*i29};
assign ii29 = {-71*r29}+{106*i29};
assign rr30 = {118*r30}-{-49*i30};
assign ii30 = {-49*r30}+{118*i30};
assign rr31 = {126*r31}-{-25*i31};
assign ii31 = {-25*r31}+{126*i31};
assign rr32 = {128*r32}-{0*i32};
assign ii32 = {0*r32}+{128*i32};
assign test1 = r22;
assign test2 = i22;
assign o_dout1 = {~rr32[15],~rr31[15],~rr30[15],~rr29[15],~rr28[15],~rr27[15],~rr26[15],~rr25[15],
                  ~rr24[15],~rr23[15],~rr22[15],~rr21[15],~rr20[15],~rr19[15],~rr18[15],~rr17[15],
						~rr16[15],~rr15[15],~rr14[15],~rr13[15],~rr12[15],~rr11[15],~rr10[15],~rr9[15],
						~rr8[15] ,~rr7[15] ,~rr6[15] ,~rr5[15] ,~rr4[15] ,~rr3[15] ,~rr2[15] ,~rr1[15]};
assign o_dout2 = {~ii32[15],~ii31[15],~ii30[15],~ii29[15],~ii28[15],~ii27[15],~ii26[15],~ii25[15],
                  ~ii24[15],~ii23[15],~ii22[15],~ii21[15],~ii20[15],~ii19[15],~ii18[15],~ii17[15],
						~ii16[15],~ii15[15],~ii14[15],~ii13[15],~ii12[15],~ii11[15],~ii10[15],~ii9[15],
						~ii8[15] ,~ii7[15] ,~ii6[15] ,~ii5[15] ,~ii4[15] ,~ii3[15] ,~ii2[15] ,~ii1[15]};						
	
assign o_dout0 = ~{rr32[15]^ii32[15],rr31[15]^ii31[15],rr30[15]^ii30[15],rr29[15]^ii29[15],
                  rr28[15]^ii28[15],rr27[15]^ii27[15],rr26[15]^ii26[15],rr25[15]^ii25[15],
						rr24[15]^ii24[15],rr23[15]^ii23[15],rr22[15]^ii22[15],rr21[15]^ii21[15],
						rr20[15]^ii20[15],rr19[15]^ii19[15],rr18[15]^ii18[15],rr17[15]^ii17[15],
						rr16[15]^ii16[15],rr15[15]^ii15[15],rr14[15]^ii14[15],rr13[15]^ii13[15],
						rr12[15]^ii12[15],rr11[15]^ii11[15],rr10[15]^ii10[15],rr9[15]^ii9[15],
						rr8[15]^ii8[15],rr7[15]^ii7[15],rr6[15]^ii6[15],rr5[15]^ii5[15],
						rr4[15]^ii4[15],rr3[15]^ii3[15],rr2[15]^ii2[15],rr1[15]^ii1[15]};				
endmodule

`timescale 1 ns / 1 ps
module tops(
            i_clk,
				i_rst,
				o_signals,
				o_sp,
				o_spflag,
				o_Dreal,
				o_Dimag,
				o_flag_fft,
				o_doutfft1,
				o_Rec
           );
 
input       i_clk;
input       i_rst;
output      o_signals; 
output[31:0]o_sp; 
output      o_spflag;
output signed[8:0]o_Dreal;
output signed[8:0]o_Dimag;
output      o_flag_fft;
output[31:0]o_doutfft1; 
output      o_Rec; 
 
 
signals signals_u(
                 .i_clk  (i_clk),
					  .i_rst  (i_rst),
					  .o_dout (o_signals)
               );
					
//Transform					
s2p s2p_u(
           .i_clk  (i_clk),
			  .i_rst  (i_rst),
			  .i_din  (o_signals),
			  .o_dout (o_sp),
			  .o_flag (o_spflag)
           );
 
//IFFT & P2S		
IFFTs_p2s IFFTs_p2s_u(
							 .i_clk   (i_clk),
							 .i_rst   (i_rst),
							 .i_en    (o_spflag),
							 .i_dn    (o_sp),
							 .o_Dreal (o_Dreal),
							 .o_Dimag (o_Dimag)
							 );
 
 
 
//Reciver
//FFT & S2P	
FFT_s2p FFT_s2p_u(
               .i_clk   (i_clk),
					.i_rst   (i_rst),
					.i_I     (o_Dreal[7:0]),
					.i_Q     (o_Dimag[7:0]),
					.o_flag  (o_flag_fft),
					.o_dout1 (o_doutfft1),
					.o_dout2 (),
					.o_dout0 (),
					.test1   (),
					.test2   ()
              );
 
//P2SA01-119
p2s p2s_u(
           .i_clk  (i_clk),
			  .i_rst  (i_rst),
			  .i_din  (o_doutfft1),
			  .i_en   (o_flag_fft), 
			  .o_dout (o_Rec)
           );
			  
endmodule

三、测试结果

        根据上面的设计原理，使用BPSK作为映射方式，最后获得如下的仿真结果：