1 WP2.3 “Radio Interface and Baseband Signal Processing” Content of D15 and Outline of D18 CAPANINA Neuchatel Meeting October 28th, 2005 – Marina Mondin –

2 WP2.3 “Radio Interface and Baseband Signal Processing” Participants: JSI, Polito, Eucon, UPC, UOY Objectives: to propose the most suitable adaptive modulation schemes and coding techniques to be used with the selected communication standards in targeting fixed and mobile operating scenarios to develop advanced signal processing algorithms for HAP using software radio architecture to implement and assess the performance of selected signal processing algorithms on a DSP platform.

3 Focus of WP2.3 From Annex 1… Proposal of possible modifications of radio interface of the selected broadband communication standards, for the implementation in identified operating scenarios Addressed baseband signal processing techniques: joint modulation and coding schemes MIMO/diversity techniques channel estimation and equalization carrier and clock synchronization Implementation on DSP platform of selected signal processing algorithms

4 Deliverable D15 “Report on required adaptations of radio interface and on baseband signal processing” Delivered by M18 (end of April 2005) MAIN QUESTIONS Do we want to suggest modifications to the IEEE SC radio interface? We have to provide consistent comparisons with different transmission systems (i.e. modulations and coding schemes, algorithms for the adaptability of the transmission schemes, bit rates, channelizations, synchronization and channel estimation algorithms etc...)

5 Focus of D15 Design and performance analysis of adaptive coding and modulation schemes, variable-rate variable-length concatenated codes, spatial and polarization diversity, MIMO coding schemes, and on the efficient implementation and testing of adaptive channel estimation algorithms. The proposed approaches are shown to be able to either increase the throughput, or to improve bit error rate performance with respect to standard solutions.

6 Advanced Coding Techniques for IEEE (Single Carrier) Example of puncturing schemes Variable-rate, variable-length bit-interleaved modulation and channel coding scheme Block diagram of the SCCC encoder. The overall code rate is Rs =RoRi

7 Advanced Coding Techniques for IEEE (SC): Comparisons The standard foresees the serial concatenation of such a RS code with a punctured CE (Convolutional Encoder) of rate 2=3 so that the overall concatenation yields a rate-1/2 code with frame sizes k = 144; n = For comparison, we designed two equivalent concatenated codes having the same rate and the same frame sizes. In particular, we considered a SCCC of size k = 144; n = 295, and a PCCC of size k = 144; n = 295.

8 Advanced Coding Techniques for IEEE (SC): Performance Evaluation of BER performance: Different coding schemes (combination of coding rates and puncturing patterns) Ricean fading channel with Rice factor equal to 10, 15 and 20 dB

9 Performance of ACM Combined with Spatial Diversity Applying space diversity to adaptive coding and modulation significantly increases the system throughput and bandwidth efficiency increase in average bandwidth efficiency using different combining methods: Selective Combining: +20% Equal Gain Combining: +30% Maximum Ratio Combining: +250% Platform diversity: when the signal from one platform is blocked due to high obstacles, the platform diversity can generally provide an alternative propagation channel with LOS conditions

10 Dual Polarized Antennas (I) Transmitter and receiver of the hybrid spatial multiplexing and space-time block codes system based on dual-polarized antennas (PM-STBC).

11 Dual Polarized Antennas (II) BER performance of PM-STBC compared to that of STBC over Ricean fading channel (K = 10) BER performance of PM- STBC compared to that of STBC over Rayleigh fading channel.

12 Channel Estimation & Synchronization Kalman filter based algorithms have been investigated as one of the most serious candidate for channel estimation and synchronization. The performance of the Kalman equaliser algorithms through DSP have been assessed by reproducing real working conditions

13 Experimentation setup Experimentation setup used to test the baseband signal processing algorithms

14 Testing the Equaliser: Some Results (a) Received and (b) equalised constellations (64-QAM, bit rate=120 Mbits, Fd=4500. Rice factor K=20 dB, Eb/No=20 dB). Eb/No BER (c) 64-QAM, bit rate=120 Mbits, Fd=4500. Rice factor K=15 dB (x-x) and K=20 dB (*-*). Training sequence length: bac

15 Conclusions of D15 In BWA the wireless link is the bottleneck, and improvements in wireless link performance directly translate to the overall improvement of the end-to-end system. In WP 2.3 advanced signal processing techniques tailored to time variant HAP-train wireless channel with IEEE /a have been proposed, and in particular: adaptive modulation and coding, highly efficient variable-rate, variable-length channel codes, spatial diversity, polarization diversity coupled with trelliscode modulations and space-time codes, adaptive channel estimation based on a Kalman filtering approach. Simulation results obtained over Rice/Rayleigh fading channels showed the effectiveness of the proposed approaches to achieve target QoS levels, often overcoming the performance of other common modulation and coding schemes, even those proposed in the IEEE standard.

16 WP2.3: the way forward Milestone M30: Implementation of selected signal processing algorithms on a DSP board Deliverable D18: Report on signal processing implementation on a DSP board (M30) Participants: JSI, Polito, Eucon, UPC, (UoY) Objectives: to implement and assess the performance of selected signal processing algorithms on a DSP platform.

17 WP2.3: contribution to D18 POLITO: finite precision implementation of selected FEC coding schemes for IEEE (SC) Analysis of metric quantization effects on the codes performances EUCON: DSP implementation of synchronization algorithms for IEEE (SC) receivers UPC: DSP implementation of Equalization algorithms for HAP applications