Software radio-based OFDM transmitting and receiving machine able to upgrade

[0045] Example

[0046] 1) Transmission of user signals of new transceivers in broadband communities

[0047] When a mobile user MS with a new type of transceiver 3 And MS 2 When data is transmitted in a broadband cell, its coded and modulated symbol series b 3 And b 2 (Length is L b 3 , L b 2 ) Are respectively mapped to M 1 (0 1 1 , 0 b 3 +L b 2 ≤M 1 ) In different subcarriers. After IFFT processing, the baseband output signal of the base station is

[0048] s l ( t ) = 1 T - T cp { Σ k = 0 M 1 - 1 d k 2 exp [ j 2 π N 1 W 1 k ( t - T cp ) ] + Σ k = 0 M 1 - 1 d k 3 exp [ j 2 π N 1 W 1 k ( t - T cp ) ] } 0 ≤ t ≤ T 0 t 0 ort T - - - ( 10 )

[0049] Here T=N 1 /W1+Tcp is the symbol duration interval, Tcp is the cyclic prefix interval, M 1 Is the number of available subcarriers, d k 3 = b 3 v k 3 and d k 2 = b 2 v k 2 , v k i (Such as v k i = 1 , Then v k j = 0 j ≠ i ) indicates that the kth subcarrier is occupied by the ith user. W1 It is the signal bandwidth (such as 40MHz), which is transmitted through the wireless channel (multipath fading channel and additive white Gaussian noise channel AWGN) to reach the MS 3 And MS 2 Respective receivers. Assuming that the user parameters can be estimated correctly, after removing the cyclic prefix and analog-to-digital conversion, the MS 3 The output signal of the kth OFDM signal after FFT processing is

[0050] y k 3 = Σ k ′ = 0 M 1 - 1 d k ′ 3 ∫ T cp T ∫ 0 T cp h ( τ ) exp [ j 2 π W 1 N 1 k ′ ( t - τ - T cp ) ] T - T cp dτ exp [ - j 2 π W 1 N 1 k ] ( t - T cp ) T - T cp dt + n k

[0051] = Σ k ′ = 0 M 1 - 1 d k ′ 3 ∫ T cp T h k ′ exp [ j 2 πk ′ W 1 N 1 ( t - T cp ) ] T - T cp exp ( - j 2 π W 1 N 1 k ( t - T cp ) dt + n k - - - ( 11 )

[0052] = Σ k ′ = 0 M 1 - 1 d k ′ 3 h k ′ δ ( k ′ - k ) + n k

[0053] = d k 3 h k + n k

[0054] Here h k ′ = ∫ 0 T cp h ( τ ) exp ( - j 2 π W 1 N 1 k ′ τ ) dτ is the sampling frequency response of the channel in the frequency domain, n k = ∫ T cp T n ( t ) exp ( - j 2 π W 1 N 1 kt ) dt is Gaussian noise with zero mean. Correspondingly, the signal obtained by MS2 is

[0055] y k 2 = d k 2 h k + n k - - - ( 12 )

[0056] Among them, the narrowband user transmission subcarrier coefficient m ranges from 0 to M 1 -1. The corresponding effective transmission bandwidth is B 1 (B 1 1 ).

[0057] 2) Transmission of different types of user signals in broadband cells

[0058] Since the narrowband basic transceiver user MS 0 And advanced broadband advanced transceiver user MS 3 Can work in different modes, including BTS with advanced transceiver 1 Send and receive two different signals and MS separately 3 And MS 0. MS 0 And MS 3 The data is mapped to length N 1 (N 1N 0 , Especially N 1 = 2N 0 ) IFFT processor M 0 (0 0 0 ) And M 1 (0 1 1 ) On the subcarrier. At the BTS1 transmitting end, the bandwidth is W 1 The OFDM signal transmitted by the baseband is:

[0059] s l ( t ) = 1 T - T cp { Σ m = 0 M 0 - 1 d m 0 exp [ j 2 π W 0 N 0 m ( t - T cp ) ] + Σ k = 0 M 1 - 1 d k 3 exp [ j 2 π W 1 N 1 k ( t - T cp ) ] } 0 ≤ t ≤ T 0 t 0 ort T - - - ( 13 )

[0060] Here, MS 0 The range of signal transmitted frequency W 0; MS 3 The range of the signal being transmitted is W 1 (W 1W 0 ).

[0061] When two users use the same subcarrier spacing (W 0 /N 0 =W 1 /N 1 , Especially 2N 0 =N 1 , 2W 0 =W 1 ), after inserting cyclic prefix and analog-to-digital converter processing, BTS 1 A broadband band-pass filter can be used to receive or transmit signals from different users. The arrangement of subcarriers is shown in Figure 5. Narrowband users can only use W 0 Green frequency B 0 Part, the frequency range available to broadband users is the frequency band W 1 Blue B 1 section. Where Δ and δ respectively represent the guard sideband of the broadband emission spectrum and the guard sideband of the narrowband emission spectrum. Finally, after passing through the radio frequency amplifier, the combined signal of the two users is transmitted by the antenna.

[0062] After wireless channel transmission, MS 3 And MS 0 The receiver separately filters the received signal, removes the prefix, and performs analog-to-digital conversion processing. After respective FFT processing and demodulation, it can obtain the data signal that it expects.

[0063] In MS 0 In the receiver, the bandwidth of the bandpass filter is B 0 , The FFT output signal is:

[0064] y m 0 = Σ m ′ = 0 M 0 - 1 d m ′ 0 ∫ T cp T h m ′ exp [ j 2 π W 0 N 0 m ′ ( t - T cp ) ] T - T cp exp ( - j 2 π W 0 N 0 m ( t - T cp ) dt + n m - - - ( 14 )

[0065] = d m 0 h m + n m

[0066] The value of m ranges from 0 to M 0 -1, the available transmission bandwidth is B 0.

[0067] And in MS 3 In the receiver, the bandwidth of the bandpass filter is W 1 , Its FFT output is

[0068] y k 3 = Σ k ′ = 0 M 1 - 1 d k ′ 3 ∫ T cp T h k ′ exp [ j 2 π W 1 N 1 k ′ ( t - T cp ) T - T cp exp ( - j 2 π W 1 N 1 k ( t - T cp ) dt + n k - - - ( 15 )

[0069] = d k 3 h k + n k

[0070] The value of m ranges from 0 to M 1 -1, the available transmission bandwidth is B 1.

[0071] 3) Signal transmission in narrowband cells

[0072] When there are two users transmitting data in a narrowband cell, one is a narrowband terminal MS 0 And one is a broadband terminal MS 1 , Narrow-band base station BTS 0 Use N 0 The point IFFT/FFT processor communicates with it. Both users use the blue part of Figure 5 to transmit signals.

[0073] After IFFT processing, the output baseband signal is

[0074] s l ( t ) = 1 T - T cp { Σ m = 0 M 0 - 1 d m i exp [ j 2 π N 0 W 0 m ( t - T cp ) ] } 0 ≤ t ≤ T 0 t 0 , ort T - - - ( 16 )

[0075] Here i∈(0,1) represents the i-th user. The baseband output signal has completed the cyclic prefix insertion, analog-to-digital conversion and frequency shift (the center frequency is f 0 ), the transmitting antenna sends this signal out.

[0076] At the receiving end, the narrowband bandpass filter (W 0 ) Receive the signal transmitted by the base station. Through their respective FFT processors, MS 0 And MS 1 The demodulated signal output is

[0077] y m 0 = Σ m ′ = 0 M 0 - 1 d m ′ 0 ∫ T cp T h m ′ exp [ j 2 π W 0 N 0 m ′ ( t - T cp ) T - T cp exp ( - j 2 π W 0 N 0 m ( t - T cp ) dt + n m - - - ( 17 )

[0078] = d m 0 h m + n m

[0079] y m 1 = d m 1 h m + n m - - - ( 18 )

[0080] Here m ranges from 0 to M 0 -1. The sum of available subcarriers for two users is M 0 , The available transmission bandwidth is B 0.

[0081] The invention applies the software radio technology to a new and scalable transceiver of the broadband mobile communication system, so that the broadband mobile station and the narrowband mobile station can effectively access the base station system. The present invention keeps the subcarrier spacing the same in different systems. In a broadband cell, the parameters of each cell user are as follows:

[0082] Comparison table of transceiver parameters for broadband mobile users and narrowband mobile users in broadband communities

[0083] Table 1 wide

[0084] The parameters are as follows:

[0085] Broadband and narrowband terminals and systems have the same sub-carrier: W 0 /N 0 =W 1 /N 1;

[0086] Broadband and narrowband terminals and systems have the same OFDM symbol period: T;

[0087] Broadband terminals and narrowband terminals have different numbers of subcarriers: M 1 And M 0;

[0088] Broadband terminals and narrowband terminals have different available spectrum ranges: B 1 And B 0;