1. 20.05.2010 | Tobias Frank Block-Interleaved Frequency Division Multiple Access (B-IFDMA) and its Application in the Uplink of Future Mobile Radio Systems Tobias Frank

2. 20.05.2010 | Tobias Frank Future Mobile Radio Systems 1 mobile terminals base station user mobilities from 0-350 km/h support of various demanding applications wide range of data rates from a few kbps to several hundreds of Mbps support of different scenarios

3. 20.05.2010 | Tobias Frank Requirements for the Multiple Access Scheme 2 mobile terminals base station high bandwidth efficiency high flexibility low delays

4. 20.05.2010 | Tobias Frank 2 mobile terminals base station high bandwidth efficiency low cost high power efficiency high flexibility low delays Requirements for the Multiple Access Scheme

5. 20.05.2010 | Tobias Frank Scenarios 3 mobile terminals base station high bandwidth efficiency low cost high power efficiency high flexibility low delays DownlinkUplink channel info at transmitter side (OFDMA) (OFDMA, LFDMA) no channel info at transmitter side (OFDMA) in the focus of this thesis

6. 20.05.2010 | Tobias Frank Outline 1.B-IFDMA Signal Model 2.Properties of B-IFDMA 3.New Algorithms for B-IFDMA 4.Summary and Conclusion 4

7. 20.05.2010 | Tobias Frank OFDMA Signal Model S/P MAPMAP IDFTIDFT P/S OFDMA signal N N.................. N subcarriers Q data symbols Q 5 CP MAP

8. 20.05.2010 | Tobias Frank DFT pre-coded OFDMA Signal Model N subcarriers Q data symbols 6 DFT pre-coded OFDMA signal DFT MAP S/P MAPMAP IDFTIDFT P/S N N.................. Q DFTDFT CP Q......

9. 20.05.2010 | Tobias Frank 7 B-IFDMA Signal Model user 1 user 2 B-IFDMA Block-interleaved allocation: N subcarriers Q data symbols S/P MAPMAP IDFTIDFT P/S N N.................. Q DFTDFT CP Q...... B-IFDMA signal

10. 20.05.2010 | Tobias Frank Interleaved allocation: Block-interleaved allocation: IFDMA user 1 user 2 7 B-IFDMA Signal Model N subcarriers Q data symbols S/P MAPMAP IDFTIDFT P/S N N.................. Q DFTDFT CP Q...... user 1 user 2 B-IFDMA B-IFDMA signal

11. 20.05.2010 | Tobias Frank user 1 user 2 B-IFDMA Localized allocation: user 1 user 2 LFDMA 7 B-IFDMA Signal Model Block-interleaved allocation: Interleaved allocation: IFDMA user 1 user 2 N subcarriers Q data symbols B-IFDMA signal S/P MAPMAP IDFTIDFT P/S N N.................. Q DFTDFT CP Q......

12. 20.05.2010 | Tobias Frank Implementation in Time Domain (1/2) 8 S/P MAPMAP IDFTIDFT P/S N N............ Q...... Q DFTDFT CP symmetric DFT:  q=0 Q - 1 d (k). e -j2  q p / Q p  n=0 N - 1 D (k). e j2  n m / N n IDFT: MAP: matrix with elements  {0,1} d(k)d(k) q x(k)x(k) n...... Q data symbols B-IFDMA signal

13. 20.05.2010 | Tobias Frank Implementation in Time Domain (2/2) 9 CP Compression & repetition by N/Q cyclic shift by ( M -1) L cyclic shift by L d(k)d(k) q x(k)x(k) n  1. Q data symbols example: N/Q=3 Q data symbols B-IFDMA signal

14. 20.05.2010 | Tobias Frank Implementation in Time Domain (2/2) 9 CP Compression & repetition by N/Q cyclic shift by ( M -1) L cyclic shift by L d(k)d(k) q x(k)x(k) n  1.  2. Q data symbols example: cyclic shift by 2 Q data symbols B-IFDMA signal

15. 20.05.2010 | Tobias Frank Implementation in Time Domain (2/2) 9 CP Compression & repetition by N/Q cyclic shift by ( M -1) L cyclic shift by L d(k)d(k) q x(k)x(k) n  1.  2. 3. multiply Q data symbols complex factor that is independent from the data symbols  can be calculated offline n element by element with  ( m,k ) n Q data symbols B-IFDMA signal

16. 20.05.2010 | Tobias Frank Implementation in Time Domain (2/2) 9 CP Compression & repetition by N/Q cyclic shift by ( M -1) L cyclic shift by L d(k)d(k) q x(k)x(k) n  1.  2. 3. multiply Q data symbols 4. sum up and insert CP element by element with  ( m,k ) n Q data symbols B-IFDMA signal

17. 20.05.2010 | Tobias Frank Computational Complexity 10 (FFT algorithm is used) - 22 % - 62 % - 94 % block size M complexity of B-IFDMA similar to OFDMA low complexity for small blocks

18. 20.05.2010 | Tobias Frank Outline 1.B-IFDMA Signal Model 2.Properties of B-IFDMA 3.New Algorithms for B-IFDMA 4.Summary and Conclusion 11

19. 20.05.2010 | Tobias Frank Envelope characteristics (1/2) 12 w/o DFT (OFDMA) PAPR of B-IFDMA always better than for OFDMA good PAPR for small and for large blocks QPSK with DFT (B-IFDMA) block size M

20. 20.05.2010 | Tobias Frank Envelope characteristics (2/2) f block interleaved random f 13 random block- interl. (B-IFDMA) random block allocation: low PAPR is lost QPSK block size M

21. 20.05.2010 | Tobias Frank Parameters for performance analysis Bandwidth40 MHz Total number of subcarriers1024 Carrier frequency3.7 GHz ModulationQPSK CodeConvolutional Code Code rate½ DecoderMax-Log-MAP Algorithmus Type of interleavingrandom Interleaving depth0.1 ms Channel: Channel modelWINNER, Base Coverage Wide Area User velocity70 km/h 14

22. 20.05.2010 | Tobias Frank Performance, frequency diversity 15 number L of blocks f Example: 12 = 4 x 3 subcarriers

23. 20.05.2010 | Tobias Frank Performance, frequency diversity 15 block size M f Example: 12 = 4. 3 subcarriers for given number Q = L. M of subcarriers: good performance for small blocks frequency diversity is exploited  low delays

24. 20.05.2010 | Tobias Frank Pilot symbol overhead for channel estimation 16 Pilot symbol = energy additional energy per payload symbol f D = no. of data symbols P = no. of pilot symbols block size M low overhead for large blocks

25. 20.05.2010 | Tobias Frank Robustness to Carrier Frequency Offsets AWGN channel  no diversity effects 17 block size M good robustness for large blocks Frequency offset: -random variable, uniformly distributed in [-f max ; f max ] -maximum offset f max =10 % of subcarrier bandwidth

26. 20.05.2010 | Tobias Frank Properties of B-IFDMA 18 high bandwidth efficiency low cost high power efficiency high flexibility low delays flexible parametrization exploitation of frequency diversity

27. 20.05.2010 | Tobias Frank Properties of B-IFDMA 18 high bandwidth efficiency low cost high power efficiency high flexibility low delays computational complexity: envelope fluctuations: frequency diversity: block size channel estimation overhead: robustness to frequ. offsets: flexible parametrization exploitation of frequency diversity

28. 20.05.2010 | Tobias Frank Properties of B-IFDMA 18 high bandwidth efficiency low cost high power efficiency high flexibility low delays low comput. complexity: low envelope fluctuations: high frequency diversity: block size low channel est. overhead: robustness to frequ. offsets: flexible parametrization exploitation of frequency diversity

29. 20.05.2010 | Tobias Frank Outline 1.B-IFDMA Signal Model 2.Properties of B-IFDMA 3.New Algorithms for B-IFDMA: 4.Summary and Conclusion 19

30. 20.05.2010 | Tobias Frank Outline 1.B-IFDMA Signal Model 2.Properties of B-IFDMA 3.New Algorithms for B-IFDMA: Space-Time Block Coding Accommodation of Different Data Rates 4.Summary and Conclusion 19

31. 20.05.2010 | Tobias Frank Space-Time Block Coding for B-IFDMA (1/2) 20 frequency... time... user 0 user 1 An approach for Space-Time Block Coding for B-IFDMA must not affect the signal envelope should work with implementation in time domain should provide low computational complexity Motivation:

32. 20.05.2010 | Tobias Frank Example: Alamouti Code (1/2) 21 frequency... time D (0) 0,0 D (0) 0,1 Elements of the DFT of the data symbols - 2 transmit antennas, - 2 consecutive OFDM symbols

33. 20.05.2010 | Tobias Frank Example: Alamouti Code (1/2) 21 frequency... time D (0) 0,0 D (0) 0,1 frequency... time D (0) 0,0 -(D (0) ) * 0,1 antenna 0 Elements of the DFT of the data symbols - 2 transmit antennas, - 2 consecutive OFDM symbols

34. 20.05.2010 | Tobias Frank Example: Alamouti Code (1/2) 21 frequency... time D (0) 0,0 D (0) 0,1 frequency... time D (0) 0,0 -(D (0) ) * 0,1 frequency... time D (0) 0,1 (D (0) ) * 0,0 antenna 0 antenna 1 Elements of the DFT of the data symbols - 2 transmit antennas, - 2 consecutive OFDM symbols

35. 20.05.2010 | Tobias Frank Example: Alamouti Code (2/2) 22 Implementation: Low computational complexity for implementation. Maintains envelope of B-IFDMA signal. Can be applied in a similar way also to other Space-Time Block Codes. antenna 0 antenna 1

36. 20.05.2010 | Tobias Frank Requirements for the Multiple Access Scheme 23 high bandwidth efficiency low cost high power efficiency high flexibility low delays Additional performance improvement  exploitation of spatial diversity efficient implementation of STBC algorithm STBC algorithm maintains low envelope fluctuations algorithm can be applied to various STBCs

37. 20.05.2010 | Tobias Frank Outline 1.B-IFDMA Signal Model 2.Properties of B-IFDMA 3.New Algorithms for B-IFDMA: Space-Time Block Coding Accommodation of Different Data Rates 4.Summary and Conclusion 24

38. 20.05.2010 | Tobias Frank Accommodation of Different Data Rates user 1: 4 subcarriers user 2: 6 subcarriers unused subcarriers user 0: 8 subcarriers f subcarriers cannot be assigned for B-IFDMA 25 Motivation:

39. 20.05.2010 | Tobias Frank f 124 12 66444 24 222222222222 Tree Structure 26 example: 24 subcarriers

40. 20.05.2010 | Tobias Frank f 124 222222222222 12 66444 24 26 Tree Structure example: 24 subcarriers

41. 20.05.2010 | Tobias Frank f 124 222222222222 12 66444 24 26 Tree Structure example: 24 subcarriers

42. 20.05.2010 | Tobias Frank f 124 222222222222 12 66444 24 26 Tree Structure example: 24 subcarriers

43. 20.05.2010 | Tobias Frank f 124 222222222222 Example: Assignment of Subcarrier Sets 12 66444 24 27 example: 24 subcarriers user 1 user 2 unused user 0 user 3

44. 20.05.2010 | Tobias Frank f 124 222222222222 12 66444 24 27 example: 24 subcarriers user 1 user 2 unused user 0 user 3 Example: Assignment of Subcarrier Sets

45. 20.05.2010 | Tobias Frank f 124 222222222222 12 66444 24 27 example: 24 subcarriers user 1 user 2 unused user 0 user 3 Example: Assignment of Subcarrier Sets

46. 20.05.2010 | Tobias Frank f 124 222222222222 12 66444 24 27 example: 24 subcarriers user 1 user 2 unused user 0 user 3 Example: Assignment of Subcarrier Sets

47. 20.05.2010 | Tobias Frank number of subcarriers = 2 n tree structure as for OVSF (DS-CDMA) 16 8 888 44444444 32 Tree with Maximum Granularity example: 32 subcarriers 28

48. 20.05.2010 | Tobias Frank Requirements for the Multiple Access Scheme 29 high bandwidth efficiency low cost high power efficiency high flexibility low delays no resources are wasted efficient implementation by use of a tree structure different data rates can be flexibly assigned

49. 20.05.2010 | Tobias Frank Summary and Conclusions  B-IFDMA can be regarded as DFT precoded OFDMA with block-interleaved subcarrier allocation  B-IFDMA can be efficiently implemented in time domain  Due to its flexibility, B-IFDMA can be parameterized such that a good trade off between the different properties of the scheme can be obtained  Space-Time Block Coding can be efficiently applied to B-IFDMA and maintains the basic advantages of the scheme  Different data rates can be efficiently accommodated to B-IFDMA using a tree- based algorithm 30 Due to its properties, B-IFDMA can be regarded as an interesting multiple access solution for the non-adaptive uplink of future mobile radio systems.

50. 20.05.2010 | Tobias Frank References 1.T. Frank, A. Klein, and T. Haustein, “A survey on the envelope fluctuations of DFT precoded OFDMA,” in Proc. International International Conference on Communications, Beijing, China, Mai 2008. 2.T. Frank, A. Klein, E. Costa, “IFDMA: A Scheme Combining the Advantages of OFDMA and CDMA,” IEEE Wireless Communications Magazine, vol. 14, no. 3, pp. 9– 17, Jun. 2007. 3.T. Frank, A. Klein, and E. Costa, “An Effcient Implementation for Block- IFDMA,” in Proc. PIMRC 2007, Athens, Greece, Sept. 2007. 4.T. Frank, A. Klein, E. Costa, and A. Kühne, “Low Complexity and Power Effient Space-Time- Frequency Coding for OFDMA,” in Proc. of 15th Mobile & Wireless Communications Summit, Mykonos, Greece, Jun. 2006. 5.T. Frank, A. Klein, and E. Costa, "Low Complexity Multi Carrier Multiple Access with Cyclic Delay Diversity," Proc. of International ITG/IEEE Workshop on Smart Antennas 2006, Ulm, Germany, Mar. 2006. 6.T. Frank, A. Klein, E. Costa, and E. Schulz, “Interleaved Orthogonal Frequency Division Multiple Access with Variable Data Rates,” in Proc. International OFDM Workshop 2005, Hamburg, Germany, Aug./Sep. 2005, pp. 179–183. 7.T. Frank, A. Klein, E. Costa, and E. Schulz, “IFDMA - A Promising Multiple Access Scheme for Future Mobile Radio Systems,” in Proc. PIMRC 2005, Berlin, Germany, Sep. 2005. 31

51. 20.05.2010 | Tobias Frank References 8.T. Frank, A. Klein, E. Costa, and E. Schulz,“Low Complexity Equalization with and without Decision Feedback and its Application to IFDMA,” in Proc. PIMRC 2005, Berlin, Germany, Sep. 2005. 9.T. Frank, A. Klein, E. Costa, and E. Schulz, “Robustness of IFDMA as Air Interface Candidate for Future High Rate Mobile Radio Systems,” in Advances in Radio Science, Miltenberg, Germany, Oct. 2004. 10.A. Sohl, T. Frank, and A. Klein, “Channel Estimation for DFT precoded OFDMA with blockwise and interleaved subcarrier allocation,” in Proc. International OFDM Workshop 2006, Hamburg, Germany, Aug. 2006. 11.A. U. T. Amah, T. Frank, and A. Klein, “On Combining SDMA and B-IFDMA: Multi-User Detection and Channel Estimation,” in Proc. of International ITG Workshop on Smart Antennas (WSA) 2010, Bremen, Germany, Feb. 2010, pp. 434–441. 12.T. Svensson, T. Frank, T. Eriksson, D. Aronsson, M. Sternad, and A. Klein, “Block Interleaved Frequency Division Multiple Access for Power Effciency, Robustness, Flexibility and Scalability,” EURASIP Journal on Wireless Communications and Networking, Article ID 720973, 2009. 13.T. Svensson, T. Frank, D. Falconer, M. Sternad, E. Costa, and A. Klein, “B-IFDMA - A Power Effcient Multiple Access Scheme for Non-frequency-adaptive Transmission,” in Proc. 16th Mobile & Wireless Communications Summit, Budapest, Hungary, Jul. 2007. 14.A. Sohl, T. Frank, and A. Klein, "Channel estimation for block interleaved frequency division multiple access scheme," Proc. of International Workshop on Multi-Carrier Spread-Spectrum, Herrsching, Germany, Mai 2007. 32

52. 20.05.2010 | Tobias Frank Thank you!

53. 20.05.2010 | Tobias Frank General Signal Model S/P MAPMAP IDFTIDFT P/S modulated data vector of user k N N............ L...... N = number of subcarriers L/Q = CDMA spreading factor N/L = no. of users separated by FDMA K = N/Q = number of users CP = insertion of cyclic prefix S = Spreading Matrix P = non-redundant pre-coding matrix vector of Q data symbols of user k Q PS............ L CP

54. 20.05.2010 | Tobias Frank B-IFDMA Receiver Model received symbol vector with CP r CP -1 S/P...... DFTDFT...... DEMAPDEMAP............ d (K-1) NNQQQ estimates the K vectors of Q data symbols of user k=0,...,K-1...... N – number of subcarriers K – number of users = N/Q CP -1 – removal of cyclic prefix DFT – Discrete Fourier Transform (OFDM demodulation) DEMAP – subcarrier demapping, user separation FDE (k) – frequency domain equalizer for user k IDFT – Inverse Discrete Fourier Transform FDE ( K-1 ) IDFT d (0) FDE (0) IDFT Advantage: Low complexity for user separation and channel equalization.

55. 20.05.2010 | Tobias Frank Cyclic Channel CP -1 h (k) CP P/S S/P IDFTIDFT DFTDFT............ Channel of user k insertion of CP removal of CP............ A 0 A 1 A 2 A 3. A N-1 B 0 B 1 B 2 B 3. B N-1 A 0 A 1 A 2 A 3. A N-1 B 0 B 1 B 2 B 3. B N-1 H (k) 0 0... 0 0 H (k) 0... 0 0 0 H (k) 0... 0 0 0... 0 H (k)........................... 0 1 2 N-1 DFT of the elements of h (k)

56. 20.05.2010 | Tobias Frank Envelope characteristics (2/2) 14 w/o DFT (OFDMA) with DFT LFDMA, IFDMA w/o DFT (OFDMA) with DFT LFDMA, IFDMA For higher order modulation the envelope fluctiations of B-IFDMA increase. For 64QAM the envelope fluctuations are still much lower than for OFDMA. QPSK 64QAM

57. 20.05.2010 | Tobias Frank Performance, comparison with LFDMA with frequency hopping Performance of LFDMA + FH improves with increasing number N t of hops. BER performance for different numbers N t of hops (B)-IFDMA with sufficient number of blocks performs better than LFDMA + FH. LFDMA (B)-IFDMA Q = 64 subcarriers per user LFDMA + FH

58. 20.05.2010 | Tobias Frank Performance, frequency diversity Performance improves Required E b /N 0 at BER=10 -3 with increasing number L of blocks. with increasing number Q of subcarriers per user, i.e., increasing data rate. number L of subcarrier blocks increasing data rate LFDMA IFDMAsaturation at L  B/B c B =system bandwidth B c = coherence bandwidth

59. 20.05.2010 | Tobias Frank SDMA

60. 20.05.2010 | Tobias Frank Time Domain Implementation, IFDMA