New Fast Power Control IE for CLPC Document

New Fast Power Control IE for CLPC Document Number: IEEE S 802. 16 maint-08/068 Date Submitted: 2008 -01 -16 Source: Jungnam Yun Dongjun Lee Kukjin Song Jaemyung Jang POSDATA Co. , Ltd. Venue: IEEE 802. 16 Rev 2/D 2 Base Contribution: Email: jnyun@posdata-usa. com Purpose: Adopt the proposed solution and incorporate it in the P 802. 16 Rev 2 draft Notice: This document does not represent the agreed views of the IEEE 802. 16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802. 16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: <http: //standards. ieee. org/guides/bylaws/sect 6 -7. html#6> and <http: //standards. ieee. org/guides/opman/sect 6. html#6. 3>. Further information is located at <http: //standards. ieee. org/board/pat-material. html> and <http: //standards. ieee. org/board/pat >.

MOTIVATION • Problem statements – For FDD mode, CLPC may have higher chance to be used than OLPC for the fast power control. – FPC is preferred to Power control IE for CLPC due to less overhead. – However, the overhead for FPC is still too much (672 bits for 25 users, for example) – We need to reduce the overhead with minimal changes to have better performance.

Current CLPC Methods • Power Control IE • Fast Power Control Message

Current CLPC Methods • Power Control IE – Individual Power Control: Basic CID shall be used for CID in UL-MAP IE – Large overhead: UL-MAP_IE + Power Control IE = 20 + 24 = 44 bits per MS; overhead = 44×N bits – For 20 MS, 880 bits = 110 bytes, which is 19 slots for QPSK ½ and 76 slots for QPSK ½ 4 R; occupies about 5 OFDMA symbols

Current CLPC Methods • Power Control IE Syntax Power_Control_IE(){ Extended UIUC Length Power Control Power measurement frame } Size Notes (bit) -- -4 Power Control = 0 x 00 4 Length = 0 x 01 Signed integer, which expresses the change in 8 power level (in 0. 25 d. B units) that the SS should apply to correct its current transmission power. 8 --- --

Current CLPC Methods • Fast Power Control Message – Can be used for multiple MS – Large overhead: MAC header + FPC Message = 48 + 48 = 96 bits for one MS. For additional MS, 24 bits are added. Overhead = 96 + 24×(N-1) – For 20 MS, 552 bits = 69 bytes, which is 12 slots for QPSK ½ and 48 slots for QPSK ½ 4 R; almost 4 OFDMA symbols.

Current CLPC Methods • Fast Power Control Message Syntax Size (bit) Fast_Power_Control message format() { Management Message Type = 38 Number of Stations Power measurement frame for (i=0; i < Number of Stations; i++) { Basic CID Power adjust } } -8 8 8 -16 8 --- Notes -----

Findings • Fast Power Control Message has less overhead than Power Control IE when there exist more than 4 MS which requires power adjustments • Redundancies in Fast Power Control Messages – Basic CID (16 bits) – can be reduced by using RCID – Power adjust (8 bits) – signed values with step size of 0. 25 d. B ± 1 d. B power adjustment is enough

Uplink Performance Test • Performance Difference of 0. 25 d. B over 1 d. B step size – – – Lab test with channel emulator for PEDA 3 km/h iperf for UDP traffic generation Fixed size packet: 1. 4 Kbytes Set Tx Rate [kbps]: 200, 400, 600, 800, 1000, 1500, 2000 Test over 30 sec for each trial Average throughput for multiple trials shows not much difference • Case 1 – 0. 25 d. B step size power control PC_IE every frame • Case 2 – 1 d. B step size power control PC_IE not every frame Tx Rate [kbps] 200 400 600 800 1000 1500 2000 Throughput Difference of Case 1 over Case 2 -0. 3% 1. 2% 0. 8% -0. 7% 2% 0. 3%

Proposed Method • Fast Power Control IE Syntax Size Notes Fast_Power_Control_IE() { Extended-2 UIUC Length Number of Stations Power measurement frame 4 bits 8 bits New power control = 0 x. XX Length in bytes --0 b 00: Normal CID 0 b 01: RCID 11 0 b 10: RCID 7 0 b 11: RCID 3 -- RCID Type for (i=0; I < Number of Stations; i++) { -- RCID_IE() variable -- Power adjust 1 bit 0 x 0 -1 d. B, 0 x 1 +1 d. B --variable Padding to byte; shall be set to 0 } Padding } 2 bits

Proposed Method • Proposed Fast Power Control IE – Can be used for multiple MS – Small overhead: • RCID 3: UL-MAP IE + Fast Power Control IE = 20 + 40 (including padding 5 bits) = 60 bits, for additional MS; +4 bits. • RCID 7: UL-MAP IE + Fast Power Control IE = 20 + 40 (including padding 1 bits) = 60 bits, for additional MS; +8 bits. • RCID 11: UL-MAP IE + Fast Power Control IE = 20 + 48 (including padding 5 bits) = 68 bits, for additional MS, +11 bits. – For 20 MS: • RCID 7: 212 bits ~27 bytes; 5 slots for QPSK ½ and 20 slots for QPSK ½ 4 R • RCID 11: 292 bits ~37 bytes; 7 slots for QPSK ½ and 28 slots for QPSK ½ 4 R