Submission doc.: IEEE ahr0 November 2011 Klaus Doppler, NokiaSlide 1 Sequence design for parallel ACK Date: Authors:

Submission doc.: IEEE ahr0 November 2011 Klaus Doppler, NokiaSlide 2 Abstract Parallel ACK is crucial to the success of Probe and Pull MAC This presentation gives more details on the parallel ACK design for ah

Submission doc.: IEEE ahr0 Parallel ACK Mechanism [1] STAs having data to send transmits ACKs concurrently (in time-aligned manner) Detection at AP impaired by parallel ACKs Need methods for resolving parallel ACKs Slide 3Klaus Doppler, Nokia November 2011 SIFS Probe AP STA1 ACK STA2 ACK STA3 STA4 ACK Pull SIFS have data to send

Submission doc.: IEEE ahr0 Parallel ACKs Parallel ACKs are separated in code-domain Sequence ID identifies STA ID Slide 4Klaus Doppler, Nokia November 2011 Time for ACK frame Sequence 1 (STA 1) Sequence 2 (STA 2) Sequence 3 (STA 3) Sequence 4 (STA 4) Code-domain

Submission doc.: IEEE ahr0 Sequence for STA Identification (1/2) Slide 5Klaus Doppler, Nokia November 2011 root of sequence integer length of sequence Cyclic shift by k

Submission doc.: IEEE ahr0 Sequence for STA Identification (2/2) Slide 6Klaus Doppler, Nokia November 2011

Submission doc.: IEEE ahr0 (a) Map a part of ZC sequence to OFDM subcarriers Meet spectrum mask Take advantage of existing OFDM structure DFT (or IDFT) of ZC sequence has unit amplitude ̶ Limits PAPR and bounds interference to other STAs Parallel ACK Transmission Slide 7Klaus Doppler, Nokia November 2011 PART 1PART 2…PART 8 ZC sequence for STA1 … ACK PART 1PART 2…PART 8 STA1 STA2 ZC sequence for STA2 CPpart 1 CPpart 1 (a) (b) CPpart 8 CPpart 8 (a) (b) (a) (b) … (b) IFFT and add cyclic prefix (CP) ACK_STA1 ACK_STA2 Parallel ACKs to AP

Submission doc.: IEEE ahr0 Parallel ACK Reception Slide 8Klaus Doppler, Nokia November 2011 AP ACK_STA1 + ACK_STA2 T FFT T RTT : max round-trip timeT MD : max. multipath delay T CP T RTT T MD T CP : CP duration T CP CP part 1 CP part 2 CP part 1 CP part 2 … … ACK_STA1 ACK_STA2

Submission doc.: IEEE ahr0 Parallel ACK Detection Active user identification ̶ Joint detection of the number of active users and their identities Asynchronous detection ̶ Packet arrival with delays (maximum delay with 6us) Non-coherent detection ̶ In interference limited scenario (i.e., there are multiple STAs sending ACKs), channel estimation is challenging Slide 9Klaus Doppler, Nokia November 2011

Submission doc.: IEEE ahr0 Simulation Setup Slide 10Klaus Doppler, Nokia November 2011 Channel Bandwidth2MHz Channel modelSCM Urban Macro [2] FFT Size/Number of Subcarriers64/56 IFFT/FFT Period32us/32us Max Propagation Delay6us (1km range) Cyclic Prefix Duration12us (> 6us + 2us) OFDM Symbol Duration44us (12us + 32us) ACK Frame Duration (8 OFDM SYMs)352us Max Number of Sequences64 64 ZC sequences Length of seq. Root indexAmount of cyclic shifts Nzc=443 q= q=

Submission doc.: IEEE ahr0 Simulation Results Slide 11Klaus Doppler, Nokia November 2011

Submission doc.: IEEE ahr0November 2011 Klaus Doppler, NokiaSlide 12 References [1] PP MAC contribution [2] J. Salo et al, “3GPP Spatial Channel Model,” [Online] Available:

Submission doc.: IEEE ahr0Month Year John Doe, Some CompanySlide Template Instructions 1/4 To properly identify your PowerPoint presentation as an IEEE Submission there are 7 steps that you must complete, and 12 data fields that you must fill in. –Step 1. Obtain a document number (has the form yy/xxxx). –Step 2. Title slide: Fill in the presentation subject title text, the full date (in ISO 8601 format of YYYY-MM-DD), and the complete author(s) details (a total of 3 data fields). –Step 3. Abstract slide: Fill in the abstract text. –Step 4. Press “Office” button, Prepare / Properties. Fill in the 2 data fields: Author field = first author's name Title field = Title of presentation

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