New Fast Power Control IE for CLPC Document Number: IEEE S802.16maint-08/068 Date Submitted: Source: Jungnam Yun Dongjun Lee Kukjin Song Jaemyung Jang POSDATA Co., Ltd. Venue: IEEE802.16Rev2/D2 Base Contribution: Purpose: Adopt the proposed solution and incorporate it in the P802.16Rev2 draft Notice: This document does not represent the agreed views of the IEEE 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 Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and.

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 = = 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 4R; occupies about 5 OFDMA symbols

Current CLPC Methods Power Control IE Syntax Size (bit) Notes Power_Control_IE(){-- Extended UIUC4Power Control = 0x00 Length4Length = 0x01 Power Control8 Signed integer, which expresses the change in power level (in 0.25 dB units) that the SS should apply to correct its current transmission power. Power measurement frame8-- }

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

Current CLPC Methods SyntaxSize (bit)Notes Fast_Power_Control message format() {-- Management Message Type = Number of Stations8-- Power measurement frame8-- for (i=0; i < Number of Stations; i++) {-- Basic CID16-- Power adjust8-- } } Fast Power Control Message

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 dB  ± 1dB power adjustment is enough

Uplink Performance Test Performance Difference of 0.25 dB over 1 dB step size –Lab test with channel emulator for PEDA 3km/h –iperf for UDP traffic generation –Fixed size packet: 1.4Kbytes –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 Case1 – 0.25 dB step size power control  PC_IE every frame Case2 – 1 dB step size power control  PC_IE not every frame Tx Rate [kbps] Throughput Difference of Case 1 over Case %1.2%0.8%-0.7%2%0.2%0.3%

Proposed Method Fast Power Control IE SyntaxSize Notes Fast_Power_Control_IE() { Extended-2 UIUC4 bitsNew power control = 0xXX Length8 bitsLength in bytes Number of Stations8 bits-- Power measurement frame8 bits-- RCID Type2 bits 0b00: Normal CID 0b01: RCID11 0b10: RCID7 0b11: RCID3 for (i=0; I < Number of Stations; i++) {-- RCID_IE()variable-- Power adjust1 bit0x0 -1dB, 0x1 +1dB }-- PaddingvariablePadding to byte; shall be set to 0 }

Proposed Method Proposed Fast Power Control IE –Can be used for multiple MS –Small overhead: RCID3: UL-MAP IE + Fast Power Control IE = (including padding 5 bits) = 60 bits, for additional MS; +4 bits. RCID7: UL-MAP IE + Fast Power Control IE = (including padding 1 bits) = 60 bits, for additional MS; +8 bits. RCID11: UL-MAP IE + Fast Power Control IE = (including padding 5 bits) = 68 bits, for additional MS, +11 bits. –For 20 MS: RCID7: 212 bits ~27 bytes; 5 slots for QPSK ½ and 20 slots for QPSK ½ 4R RCID11: 292 bits ~37 bytes; 7 slots for QPSK ½ and 28 slots for QPSK ½ 4R