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#1 2014-Nov-12 04:07:29

adherentx
Member
Registered: 2014-Oct-23
Posts: 45

How long is the decoding time of 802.11 Ref Design on WARP v3?

Actually I have two problems about implementing relaying function on WARP v3.

1. How long is the decoding time (from an OFDM packet is detected to the OFDM data is available) of 802.11 Ref Design on WARP v3?
2. How to re-enqueue a received packet to transmit? (a node acting as a relay)

Thanks.

Last edited by adherentx (2014-Nov-12 04:13:14)

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#2 2014-Nov-12 09:32:22

murphpo
Administrator
From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: How long is the decoding time of 802.11 Ref Design on WARP v3?

1. How long is the decoding time (from an OFDM packet is detected to the OFDM data is available) of 802.11 Ref Design on WARP v3?

The time from detection to completion of decoding is determined by the packet's duration (approximately preamble + rate*length; see IEEE 802.11-2012 18.4.3 "OFDM TXTIME calculation" for the details).

The PHY's overall latency is constrained by the 6usec signal extension provided by the spec. Our PHY implementation meets this requirement for all rates/lengths. The time between reception of the arrival of the sample of a packet and the decoding of the last byte is <6usec. The actual time varies with packet rate/length, but will always be <6usec.

2. How to re-enqueue a received packet to transmit? (a node acting as a relay)

The easiest place for this is in the MAC code in CPU High, as part of the mpdu_rx_process() function. Our AP code actually implements this to handle communication between association stations. If STA 1 has data for STA 2, STA 1 constructs a packet with dest_addr = STA 2 and to_ds = 0, then transmits it to the AP. The AP recognizes the packet as destined to another associated STA. It then constructs a new Tx packet, copies the payload from the received packet, then en-queues it for transmission to STA 2. See mpdu_rx_process() in wlan_mac_ap.c for our implementation of this.

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