July 2004 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Modified Delayed (Dly) Acknowledgement for IEEE 802.15.3 Systems] Date Submitted: [28th June , 2004] Source: [Sanjeev K. Sharma and Jinwoo Hong] Company [Samsung Electronics] Address [75 W. Plumeria Dr, San Jose, CA, 95134] Voice:[+1-408-544-5978], FAX: [+1-408-544-5666], E-Mail:[sk.sharma@samsung.com] Re: [] Abstract: [ Modified Delayed (Dly) Acknowledgement for IEEE 802.15.3 Systems] Purpose: [For discussion to modify delayed acknowledgement in 802.15.3 Systems and include the proposed modified Dly ACK] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Sanjeev K. Sharma et al, Samsung

Modified Delayed (Dly) ACK for IEEE 802.15.3 Systems July 2004 Modified Delayed (Dly) ACK for IEEE 802.15.3 Systems July 2004 Sanjeev K. Sharma et al, Samsung

July 2004 Problem Definition To use Dly ACK as per current IEEE 802.15.3 MAC draft, Each MPDU received is Delay (Dly) ACKed using 2 Bytes for each MPDU Size of Delayed (Dly) ACK frame increases with increase in number of MPDU blocks Larger size of 802.15.3 Delayed (Dly) ACK frame reduces the probability of its successful transmission, which may cause retransmission of all the frames causing bandwidth wastage Sanjeev K. Sharma et al, Samsung

July 2004 Delayed (Dly) ACK in 802.15.3 Each MPDU needs two (2) bytes for Dly ACK Size of Dly ACK increases with increase in MPDU Blocks Figure 1: Fragmentation Control Field of IEEE 802.15.3 MAC Header octets: 4 FCS 2 MPDU ID block-n … block-2 block-1 1 MPDUs ACKed MAX Frames Burst 10 MAC header bits: b15-b9 Fragment Number b8-b0 MSDU Figure 2: Delayed (Dly) ACK for IEEE 802.15.3 Sanjeev K. Sharma et al, Samsung

Proposed Delayed (Dly) ACK July 2004 Proposed Delayed (Dly) ACK Proposed modified Dly ACK is shown in Figure 3 We need up to 16 bytes (128 bits as there are max 128 fragments) to Dly ACK each MSDU First Fragment Number field is from where we want to start the Dly ACK octets: 4 octets: 4 0~16 0~16 2 2 … … 0~16 0~16 2 2 1 1 1 1 1 1 10 10 octets: 4 octets: 4 0~16 0~16 2 2 … … 0~16 0~16 2 2 1 1 1 1 1 1 10 10 Bitmap for Bitmap for Bitmap for Bitmap for MPDUs MPDUs MAX MAX MAX MAX FCS FCS Bitmap for Bitmap for MSDU n MSDU n … … Bitmap for Bitmap for MSDU 1 MSDU 1 MPDUs MPDUs MAX MAX MAX MAX MAC header MAC header FCS FCS MSDU n MSDU n MSDU n MSDU n … … MSDU 1 MSDU 1 MSDU 1 MSDU 1 ACKed ACKed Frames Frames Burst Burst MAC header MAC header MSDU n MSDU n MSDU 1 MSDU 1 ACKed ACKed Frames Frames Burst Burst bits: b15 bits: b15 - - b9 b9 b8 b8 - - b0 b0 bits: b15 bits: b15 - - b9 b9 b8 b8 - - b0 b0 First Fragment First Fragment MSDU MSDU First Fragment First Fragment MSDU MSDU Number Number Number Number Number Number Number Number Figure 3: Proposed Modified Delayed (Dly) ACK for IEEE 802.15.3 MAC Sanjeev K. Sharma et al, Samsung

Example: Multiple MSDUs (1/2) July 2004 Example: Multiple MSDUs (1/2) Modified Dly ACK for Multiple MSDUs without any MSDU loss is shown in Figure 4. Delay ACKed are fragments 50~60 of MSDU1 and fragments 0~7 of MSDU2. octets: 4 FCS MSDU n 0~16 Bitmap for MSDU 1 2 1 MPDUs ACKed MAX Frames Burst 10 MAC header MSDU 2 ACKed (19) bits: b15 - b9 Number b8 b0 MSDU First Acked Fragment Number (50) (1) b15-b11 b00000 b10 b111..11 bits: b7 Number (0) (2) 1 byte 2 bytes Figure 4: To ACK Multiple MSDUs using Proposed Dly ACK Sanjeev K. Sharma et al, Samsung

Example: Multiple MSDUs (2/2) July 2004 Example: Multiple MSDUs (2/2) Modified Dly ACK for Multiple MSDUs with loss of one fragment (52) is shown in Figure 5. Delay ACKed are fragments 50~60 of MSDU1 and fragments 0~7 of MSDU2. octets: 4 FCS MSDU n 0~16 Bitmap for MSDU 1 2 1 MPDUs ACKed MAX Frames Burst 10 MAC header MSDU 2 ACKed (18) bits: b15 - b9 Number b8 b0 MSDU First Acked Fragment Number (50) (1) b15-b11 b00000 b10 b111..011 bits: b7 b111..11 Number (0) (2) 1 byte 2 bytes Figure 5: To ACK Multiple MSDUs with One Lost Fragment using Proposed Dly ACK Sanjeev K. Sharma et al, Samsung

Performance Comparison July 2004 Performance Comparison Table: Performance Comparison Excluding size of MAC header, Max Burst, Max Frames, and MPDUs ACKed, which is 17 bytes. Saving = (529-53)/529 89.98% Parameter Name Dly ACK Modified Dly ACK Max number of MPDUs to be Dly ACKed 256 Max Number of Fragments 128 Size of Dly ACK frame body for 256 MPDUs (Max) 256*2 = 512 (bytes) 2*18 = 36 (bytes) Size of Dly ACK Frame 512+17 = 529 (bytes) 36+17 = 53 (bytes) Sanjeev K. Sharma et al, Samsung

July 2004 Advantages We save Delay (Dly) ACK overhead significantly (up to 90%) by using the (proposed) bitmap fields. Proposed scheme improves the throughput efficiency of the overall system. Improves the chances of successful transmission of Dly ACK, which reduces the probability of retransmission of all frames. In case of non-fragmented MSDUs, modified Dly ACK is identical to Dly ACK. Easy to implement. Sanjeev K. Sharma et al, Samsung

July 2004 Proposal to 802.15.3b Adopt the modified Delayed (Dly) ACK mechanism in IEEE 802.15.3b Sanjeev K. Sharma et al, Samsung

July 2004 References Wireless Medium Access Control (MAC) and Physical (PHY) Layer Specifications for High Rate Wireless Personal Area Networks (WPAN), Draft P802.15.3/D17, February 2003. Sanjeev K. Sharma et al, Samsung