IEEE Wireless Access Method and Physical Layer Specifications. The potential of Dynamic Power Control

Transcription

1 dc: EEE P82.-92/76 EEE 82. Wireless Access Methd and Physical Layer Specificatins Title: Presented by: The ptential f Dynamic Pwer Cntrl Wim Diepstraten NCR SE-Utrecht NCR/AT&T Netwrk Prduct Grup Nieuwegein The Netherlands (V) (Fax) Wim.Diepstraten@Utrecht.ncr.cm ( ) ssue's addressed: Medium re-use efficiency strategy. What is the strategy fr capacity cntrl Must the MAC wrk n a single channel PHY Requirements fr the MAC/PHY interface. s MAC/PHY exchange needed fr Management What is the MAC Frame structure (7-?) (9-7) (25-3) (2-2) (3-5) (2-4) Abstract: Cnclusin: This paper describes a Dynamic Pwer Cntrl scheme, and its use in a single channel distributed cntrl access prtcl envirnment. The cncept is simulated with the same three "Listen Befre Talk" class f prtcls used in Dc P /5. The medium re-use ptential is explained, and the relevant requirements fr the MAC/PHY interface are given Medium re-use efficiency is a majr cncern fr especially single channel systems. As explained in Dc P82.-92/5, the medium will be (c-channel) interference limited rather than nise limited. A methd t imprve the medium re-use efficiency has been intrduced, that dynamically limits the Transmit pwer (and an assciated "Defer" threshld) t a level needed fr reliable cmmunicatin per individual destinatin. Submissin Page By: Wim Diepstraten

2 dc: EEE P82.-92/76 Analyses and simulatins presented have shwn that large re-use efficiency imprvements can be btained depending n the physical size f the BSA. This Dynamic Pwer Cntrl facility can be an ptin, and it can wrk in a mixed envirnment. The nly thing we need t standardize n is tw extra Bytes in the MAC frame structure that cntain settings fr the transmit pwer with which the packet was transmitted, and a "Silence Level" Byte that represents the average interference level at the lcatin f the transmitter. The resulting requirements fr the MAC/PHY interface wuld be t have a MAC t PRY management interface available fr cntrl and status exchange, ver which the MAC shuld have full cntrl. ntrductin: Cntributin P82.-92/5 cmpared different distributed access prtcl alternatives. One f the relatins simulated was the Ttal Thrughput as functin f the distance between tw netwrks in bth a peer-t-peer (Fig 6), and in a Client-Server (Fig 9) netwrk lad. ndividual statin behavir was shwn in Fig 7 and respectively. t shuld be nted, that this simulatin invlved a hmgeneus envirnment, with the average attenuatin cefficient that represent a typical pen ffice envirnment. Althugh the results shw the sharing effects, it is less realistic fr practical use. n reality yu wn't find buildings that are 8 meters square, withut any majr attenuatin bstructin like cncrete Walls, and things like elevatr shafts, which highly effect the prpagatin cnditins ver larger distances. Therefre it is mre apprpriate t lk at Fig 7a and loa where an additinal 2 db attenuatin step is assumed between 2 netwrks, which can be cnsidered as an effect f a cncrete wall, r flr t flr attenuatin. This still means hwever that under these cnditins and with the sensitivity levels used, the same medium must be shared between a cnsiderable number f BSA's. t lks like that under the described circumstances the medium needs t be shared with 4-6 ther netwrks n the same flr, and at least ne n the flr belw, and ne flr abve fr a multi-stry building. T assure prper receiving cnditins, a sufficient Signal t nterference Rati (SR) is required at the receiver. Therefre it is required t frce ther medium cntenders t be silent in an area arund the intended receiver. The area that needs t be frced silent will depend n the received signal level f the wanted signal at the receiver. When the transmit pwer is adjusted t a level suitable t assure a required SR, significant lwer pwer levels can be used fr all statins clser t the transmitter. This will in tum reduce the c-channel interference levels in neighbr BSA's, and cnsequently allw fr a better re-use f the medium. Submissin Page 2 By: Wim Diepstraten

3 dc: EEE P82.-92/76 Please nte that this is cmpletely independent f the access prtcl used. This paper prpses a methd that allws fr Dynamic Pwer Cntrl, and intrduces the functins required in the MAC and PHY, t supprt this. Therefre it presents the functinality needed in the MAC(PHY interface. Pwer Cntrl System descriptin n the prpsed system the transmit level, and the defer threshld can be changed as a functin f the destinatin f the packet. This means that fr clse-by destinatins much less transmit pwer can be used t achieve an acceptable SR cnditin at the receiver statin. Transmitters in nearby ther netwrks can then utilize the medium at the same time, because they dn't have t defer fr the much weaker signal. This makes re-use f a certain frequency band pssible. When a transmitter wants t transmit t a nearby statin with a reduced pwer level, then its defer threshld shuld be reduced as well t take advantage f the fact that the defer distance can be reduced. Otherwise this transmitter wuld still defer fr any statin within the maximum defer bundary (4 meter as illustrated in figure and 2 in the example system). Hw t determine the transmit and defer levels: The idea is that addressed receivers can measure the signal level f the received signal cming frm a specific surce. By default the attenuatin between tw pints is unknwn after startup f the system, s they shuld transmit at full pwer. Per cnnectin the receive level shuld be averaged ver a number f measurements t decrease the effect f fading when statins are mving. Fr this methd t wrk, the receivers shuld knw the pwer level with which the packet was transmitted. This infrmatin can be included as a separate byte in the MAC frame structure. By reading this byte and subtracting the actual receive level, the signal path attenuatin (at that mment) can be calculated. As already explained, by averaging f this attenuatin value ver a number f packets received frm that surce, the average path attenuatin can be determined. This value can be an input t an algrithm that determines the transmit level and the defer threshld, using apprpriate margins fr fading. The resulting values can s be maintained by the MAC in a table, referenced by the destinatin address, s that every time a packet is t be transmitted, the relevant Tx-pwer level and defer threshld can be prgrammed frm that table. Nte that different algrithms may be needed fr mbile statins, than fr fixed statins, because fr mbile statins, the average attenuatin will vary ver time, s that the averaging algrithm time cnstant shuld be small t allw fast adaptin t the attenuatin situatin. Submissin Page 3 By: Wim Diepstraten

4 dc: EEE P82.-92/76 B Attenuatin ceff = 3.5 Receiver Sensitivity = -75 dbl' tal cverage range = -7 dbl' Defer Threshld = -82 dbl' Signal nterference Rati= B db? Figure Explanatin f Fig-: The figure shws tw relatins. One is the average prbability receive signal level as functin f distance t the transmitter (lcated at the rigin). The transmit utput level measured at meter frm the surce is in this case -6 dbm. The shwn average prbability attenuatin as functin f distance is typical fr an indr pen ffice envirnment. Fr ease f explanatin it is assumed that the envirnment is hmgeneus, s nt further separated by attenuatin bundaries like walls r ceilings. n additin n margins are included yet t limit the utage due t interference. Next n the same axis a number f circles are drawn. The uter circle represents the bundary at which the average attenuatin f the signal is such that its level is equal t the "carrier detect" threshld f the receiver. The transmitter is assumed in the rigin and the destinatin receiver Submissin Page 4 By: Wim Diepstraten

5 dc: EEE P82.-92/76 n the circle. When the radi mdems are using a CSMA type access prtcl, then this is als the average bundary fr which statins will defer fr ther transmitters in this area. Effectively all the transmitters in this area will share the same bandwidth. The middle circle wuld be the average bundary n which packets can be reliably received, when assuming a certain backgrund nise level (in this case 8 db abve thermal nise). Hwever in rder t perate with a certain bit errr rate, the interference level frm ther netwrk activity shuld be an amunt f SR db's lwer then the wanted signal. The SR value depends n the mdulatin methd and quality f the receiver implementatin. Nw when we assume that just utside the uter circle there can be a transmitter active, because we will nt defer fr such a lw level signal. Then all receivers within the inner circle will receive the wanted signal at least SR db higher than the disturbing signal. Therefre the inner circle represents the s called "Safe Cverage Area", which is typically cnsiderably smaller than the middle circle representing the bundary fr nise. On tp f this a fading margin needs t be included, t assure a lw enugh utage prbability due t fading. Advantage f dynamic Pwer Cntrl: When the destinatin f the signal is fr instance lcated at half the "Safe Cverage" distance, then in case f a fixed pwer level situatin the wanted signal is much larger than the interference signal, which will assure reliable peratin. Hwever, because f the defer mechanism, n ther transmissin can take place at the same time in an area as large as the uter circle. When the transmit level wuld have been reduced t a level that is sufficient t guarantee a SR difference between the wanted and interfering signal, then the interference level generated in ther nearby netwrks will be lwer, and cnsequently a transmitter much mre clser by culd be allwed t transmit. At the same time hwever the "Carrier threshld" r "Defer threshld", f the statin that wants t transmit at the reduced pwer level, shuld be reduced as well because therwise we wuld unnecessary defer t nearby transmissins in this case. t can be calculated that the verall re-use f the medium is apprx. a factr 3 imprved (fr the hmgeneus unifrm statin distributin case) when dynamic pwer cntrl is used. An additinal majr advantage is that a dynamic system like this will adjust its transmit pwer level, and assciated carrier threshld such that small clustered netwrks will generate much less interference t neighbr pssibly larger netwrks, s that the ttal thrughput f the system will significantly increase. Submissin Page 5 By: Wim Diepstraten

6 dc: EEE P82.-92/76 When fixed levels are used, then the transmit level and receiver threshlds are t be set as a trade-ff between cverage distance and thrughput/sharing, depending n the applicatin. This will hwever als mean that when we have nly a relative small netwrk clustered ver a small distance then we still use the full pwer and receiver sensitivity, s that we have t share the medium with all neighbring systems within a pretty large area, althugh fr reliable peratin we culd d with a lt less pwer. Als the relative thrughput f the system will increase significantly when nly enugh pwer is used as needed fr a small clustered netwrk like described. Given this situatin, then the re-use imprvement can be much higher than a factr 3, and may easily be in the rder f 3 r mre. Hw t determine the Tx-evel and Rx threshld? The attenuatin between transmitter and receiver can be determined in the receiver by measuring the received level in the receiver, and subtracting the transmit level. This transmit level shuld be indicated in a byte in the MAC frame. n additin t that als the "silence" level as measured at the transmitter side shuld be included as infrmatin in the MAC frame. At a receiver lcatin this calculated attenuatin and the silence level shuld be stred in a table indexed by the address f the transmitter. Given the measured attenuatin, an ptimum transmit level can be calculated, r lked up in a pre-calculated table, tgether with a new "defer" threshld. The "silence" level shuld be used t verify that the expected receive level is at least SR db higher than this "silence" level. f nt, than the transmit level shuld be increased accrdingly. Nte that the "silence" level is a measure fr the cntinuus interference level at that particular receiver lcatin. Hw t learn the system. The system shuld start at default maximum transmit levels and assciated defer threshlds, and will learn the mre ptimum settings when cmmunicatin prgresses. N interchange f infrmatin ther than the silence and pwer level included in the MAC frame are needed. The system culd learn frm nly the cmmunicatin addressed t that wrkstatin, and build a table nly fr thse statins that it cmmunicates with. t culd als learn frm every packet crssing the medium, and maintain a table fr all cmmunicatin it can hear. This will cst large tables, als fr thse destinatins which will prbably never be addressed by this particular wrkstatin, s this methd is nt recmmended. Usually it is imprtant t cmmunicate with a server statin. When packets frm server statins r access pints t a wired backbne are uniquely identifiable then the system culd learn frm every transmissin frm such a server statin. Submissin Page 6 By: Wim Diepstraten

7 dc: EEE P82.-92/76-6 ' - Figure 2 Pwer Cntrl f'f'ec-t DiQgrQM Nte: Fr ease f explanatin, nly the average prbability curve is shwn. n practice an apprpriate fading margin needs t be added (t the SR). Explanatin Figure-2: n figure 2 again a level versus distance plt is given fr a typical ffice envirnment, but the envirnment is assumed hmgenus withut walls. t shws that when the Defer threshld is - 82 dbm, the transmitter will defer fr all transmitters within a 4 meter range. When an interfering statin is active just utside this bundary then all statins within a 4 meter radius frm the transmitter will meet the SR criterium. Nw assume that an intended receiver is lcated at 7 meter frm the transmitter, then this lcatin culd be reached with a 6 db lwer transmit level, while sufficient SR separatin is assured fr the nminal level transmitters lcated as clse as 27 meter. Als the defer threshld can be decreased with 6 db t allw start f transmissin when n ther transmitter is active within 27 meter rather than the riginal 4 meter. Submissin Page 7 By: Wim Diepstraten

8 dc: EEE P82.-92/76 Ptential medium re-use gain. t has been analyzed that the prpsed methd has the ptential t increase the medium re-use efficiency by a factr 3 in a hmgeneus unifrm statin density envirnment. n practice this can be much larger and is a functin f the size f the netwrk. Simulatins have been dne using the simulatr describe in Dc P82.-92/26, in which the pwer cntrl mechanism is implemented. Sme result plts are shwn in the appendix. The plts shw the relatin between ttal thrughput versus the distance between tw netwrks, fr bth a peer-t-peer traffic mdel as well as a Client-Server traffic mdel. T calculate the re-use gain, it is a gd practice t take a pint n the thrughput curve which lies in the middle between the lwer and higher bundary, s the 5% pint (5% f the capacity fr ne NW). Re-use efficiency can be expressed as the increase f the capacity per unit f area. S the imprvement wuld be the relatin between the square f the distance at the 5% pint f the tw curves. S this is the rati f the area's at thse pints. This rati is called the Pwer Cntrl Efficiency (PCE) value, and is calculated fr the plts shwn. The simulatin results shw typical numbers fr the Client-Server traffic mdel used n a netwrk layut as shwn in dc P /5. Als results are shwn fr the peer-t-peer traffic mdel, which shw a lwer efficiency gain. This can be explained by the fact that the distances in the peer-t-peer case are larger, s less pwer reductin can be btained. This is equivalent t a duble size Client-Server based traffic mdel with the server lcated in the center f the area. Als the fading margin used during the test was t lw (nly 5 db), s that mre retries are needed. Additinal plts shw the Client Server results fr a smaller size netwrk, which shw higher PCE numbers as expected. Nte that fr these plts a mre realistic db fading margin is assumed, s that the plts d nt directly cmpare. The fllwing test cnditins were used fr the simulatins: Client-Server traffic mdel: Peer-t-Peer traffic mdel: RW (ReadWrite) mde with 6% Shrt 64 Byte packets and 4% Lng 52+64=576 Bytes packets. Perfrmance results shw 52 Byte data nly thrughput, s withut Nvell verhead. RW (ReadlWrite) mde with 6% Shrt 64 Byte packets and 4% Lng 52+64=576 Bytes packets. Perfrmance results shw all MAC thrughput data nly thrughput. Fading margin used in Pwer Cntrl algrithm is nly 5 db unless therwise indicated. Nte Submissin Page 8 By: Wim Diepstraten

9 dc: EEE P82.-92/76 that this is t lw fr an acceptable utage. Pwer Cntrl as an implementatin ptin. Statins culd implement Pwer Cntrl as an ptin. That means that a mixed envirnment culd exist with ne BSS using Pwer Cntrl, while a partly verlapping ther BSS wuld nt use it. Even within a BSS, there culd be a mix f statins with and withut the Pwer cntrl feature. All these mixes are pssible as lng as the extra Pwer Cntrl Bytes in the frame structure represent the fixed settings f the transceiver. This is because the Pwer Cntrl algrithm is distributed ver the statins, and nly needs t perate in the statins that have this ptin installed. Of curse the verall thrughput imprvement wuld be limited, but statins that are relative clse t their main destinatin (AP r Server), wuld benefit frm having this ptin installed. This characteristic is imprtant, because it allws fr ptinal lwer cst PRY implementatin, because thse PRY's culd be implemented withut a variable gain pwerstage, and withut a receive level measurement facility. The nly bttleneck wuld be the "Silence" level When a statin with pwer cntrl cmmunicates with a statin r AP withut any pwer cntrl prvisins, then when the destinatin is lcated near a CW type interferer, then the pwer cntrl wuld hurt, because the "Silence" r interference level is nt knwn. A statin culd learn that smething is wrng, by maintaining retry statistics, which culd cause the Pwer Cntrl t be turned ff fr that particular destinatin. Pwer Cntrl in a multi channel system. When sufficient channels are available, tgether with an efficient allcatin plan r algrithm, t assure that there is sufficient re-use distance, then Pwer Cntrl wuld nt be needed, r wuld have nly minr effect. This is when we assume that nly ne ring f cells with different frequencies (6-) is needed fr islatin, because it is likely that als a wall will be in between the frequency re-use area. This will f curse depend n the size f a BSA. When the range f a single BSA is very limited t fr instance -2 meter, then it is likely that a high density is needed t cver ne rm. S that re-use is needed within ne rm, r additinal cell rings are needed fr islatin, requiring mre channels (apprx 2). With Pwer Cntrl, re-use can be imprved s that less channels are needed fr re-use islatin. Of curse the standard shuld nt require Pwer Cntrl at all times, because there will likely be multiple channel PRY's, r lw requirement implementatins that dn't need Pwer CntrL Submissin Page 9 By: Wim Diepstraten

10 dc: EEE P82.-92/76 What prvisins are needed: The fllwing functinality is needed in different area's t supprt dynamic pwer cntrl: n the PHY: n the Frame: n the MAC: A variable gain pwer stage A received signal level measurement facility A variable "Defer" threshld A byte cntaining the level with which the packet was transmitted. A Byte cntaining the averaged "Silence" level measured at the transmitter lcatin. Facilities t dynamically cntrl the Tx-evel, and "Defer" threshld per packet. Facilities t retrieve the Receive level and "Silence" level frm the PHY. Pwer Cntrl Learning algrithm. A table with Tx-evel and Defer threshld level entries per destinatin. t may be cnsidered a disadvantage that the MAC needs t maintain a table per destinatin, with the TX-evel and Defer Threshld level. This is likely a sftware functin, and may burden the hst system. The advantage can hwever be that the same table can be used fr ther purpses. t makes it fr instance pssible that the bitrate can be changed dynamically per destinatin statin. This wuld allw t perate mst f a netwrk at a high datarate, while perhaps a few far away statins suffering frm much path attenuatin, r frm a difficult delay spread situatin can be served at a reduced bitrate. Given that AP's need t maintain similar tables anyway, (fr bridging, pwer management and thers), then this wuld have hardly any effect n the cmplexity. Statins will in practice cmmunicate with nly a limited set f destinatin statins, f which mst culd be lcated beynd the AP n the backbne, s nly a limited table needs t be maintained. Submissin Page By: Wim Diepstraten

11 dc: EEE P82.-92/76 MAC / PRY nterface requirements: Figure 3 shws a functinal blck diagram, indicating the additinal functinality needed in the interface between the MAC and the PRY. Figure 4 shws a hardware implementatin level blckdiagram in which the extra functins needed fr the supprt f Pwer Cntrl are shwn. The additinal algrithmic requirements needed are nt shwn, but these will likely be sftware functins needed in the Driver Sftware. The MAC will need t manage the PRY n a per packet basis, and will either need a dedicated management interface fr this, r will need cntrl ver any existing management interface. Befre the medium is accessed, the Tx-PwerL and Rx-THRhld values need t be dwnladed in the PRY, after which the MBUSY interface signal is being sensed as part f the "Listen Befre Talk" class f distributed access prtcl. At the end f a received packet, the Rx-evel and Silence-Lv need t be retrieved frm the PRY, t attach it t the received packet in its receive frame buffer. The "Rx-Level" can be measured anywhere within the received packet. The "Silence-Lv" shuld be measured in a defined silence perid such as the nter Frame Space (FS). t is likely that at this mment als ther PRY status is cllected that als need t be attached t the received packet. Examples will be any Quality Of Service (QOS) related status like "signal Quality". Perhaps the TxD and RxD data lines can be multiplexed fr this, t serve as a management datapath. Mre research needed: Mre research is needed t analyze the required specificatins, and t develp a suitable learning algrithm. Fr instance the effect f the tlerance f the Transmit utput level and the receive level measurement unit must be evaluated. Further analyses is needed t specify the dynamic range and discrete step sizes needed fr the variable transmit gain stage. Pssibly a different parameterized learning algrithm is needed fr mbile statins. The cnversin f measured level t desired utput pwer is an ther field f research. Submissin Page By: Wim Diepstraten

12 dc: EEE P82.-92/76 Cnclusin: A methd t imprve the medium re-use efficiency has been intrduced, that dynamically limits the Transmit pwer (and an assciated "Defer" threshld) t a level needed fr reliable cmmunicatin per individual destinatin. Analyses and simulatins presented have shwn that large re-use efficiency imprvements can be btained depending n the physical size f the BSA. This Dynamic Pwer Cntrl facility can be an ptin, and it can wrk in a mixed envirnment. The nly thing we need t standardize n is tw extra Bytes in the MAC frame structure that cntain settings fr the transmit pwer with which the packet was transmitted, and a "Silence Level" Byte that represents the average interference level at the lcatin f the transmitter. The resulting requirements fr the MAC/PRY interface wuld be t have a MAC t PRY management interface available fr cntrl and status exchange, ver which the MAC shuld have full cntrl. Submissin Page 2 By: Wim Diepstraten

13 dc: EEE P82.-92/76 DYNAMC POWER CONTROL POTENTAL * Prblem addressed Envirnment is NTERFERENCE LMTED n single channel envirnment, medium needs t be shared with a significant number f different BSA's. n multi channel envirnment a large number f channels may be needed fr re-use islatin. Fr large cells, need 6- channels. Fr small cells, need arund 2 channels. * Prpsed slutin: Reduce the c-channel interference. Limit Tx Pwer level t a value needed fr reliable receptin. Learn prper level per individual Destinatin. Use Defer threshld as functin f Pwer Level. Submissin Page 3 By: Wim Diepstraten

14 dc: EEE P82.-92/76 * Features DYNAMC POWER CONTROL POTENTAL Analyses shw factr 3 Re-use efficiency imprvement in a hmgeneus unifrm distributed envirnment (Assuming single channel system). Larger Re-use efficiency as functin f BSA size. Culd be prtcl type independent. Can perate in mixed envirnment. S can be implemented as an ptin. Easy extensin t mixed bitrate envirnment. * Simulatin Results: Simulatr described in P82.-92/26 includes Pwer Cntrl ptin. Simulated with CSMA/CA, CSMA/CA + Ack, and 4-WAY LBT. Results shw Netwrk size dependency Gd results fr all 3 prtcls. Submissin Page 4 By: Wim Diepstraten

15 dc: EEE P82.-92/76 DYNAMC POWER CONTROL POTENTAL * Prvisins needed MAC Frame structure: (Needed in Standard) PHY: MAC: One Byte indicating Tx-Pwer level One Byte indicating "Silence" / nterference Level Variable Gain Output stage Receive Level Measurement functin Variable Defer threshld Dynamic Cntrl f Tx-Level and Defer Threshld Retrieve Receive level and "Silence" level Learning algrithm Maintain Tx-LevellDefer-THRhld table per destinatin MAC / PRY nterface: Management interface under MAC cntrl Submissin Page 5 By: Wim Diepstraten

16 dc: EEE P82.-92/76 * Further research needed: Effect f hardware tlerances Dynamic range and step size requirements fr Pwer Cntrl Learning algrithm Static / mbile difference * Cnclusin: Dynamic Pwer Cntrl has gd medium re-use efficiency Ptential Als applicable t multi channel systems Can wrk in mixed envirnment Can be an implementatin ptin Only need Frame Structure prvisins in standard Need MAC/PHY management interface under MAC cntrl Submissin Page 6 By: Wim Diepstraten

17 dc: EEE P82.-92/76 Descriptin f the fllwing figures: Fig 3: Fig 4: Fig 5: Fig 6: Fig 7: Fig 8: Fig 9: Fig : Layered architecture Blckdiagram shwing the extra interface functins needed fr Pwer Cntrl. mplementatin level MAC + PRY Blckdiagram shwing the extra functinality required fr Pwer Cntrl. Als the required entries in the MAC frame structure are indicated. Shws the attenuatin versus distance diagram, with varius curves explaining the Pwer Cntrl meachanism. t als shws the MAC frame structure with the tw Bytes TPL and SSL VL required fr dynamic Pwer Cntrl. The sequence and place f the MAC frame structure is nt relevant. Shws the Ptential Pwer Cntrl efficiency fr the netwrk used in dc P82.-92/5 with a peer-t-peer traffic mdel, with randm traffic destinatin. The ttal system thrughput f tw netwrks is shwn as a functin f the distance between tw netwrks. Shws the Ptential Pwer Cntrl efficiency fr the same Netwrk, but with a Client-Server traffic mdel. This means that all traffic is with a centrally lcated Server statin. Thrughput is actual Data thrughput nly, s withut Nvell verhead. Thsi is equivalent t a Nvell Perfrm3 test. Shws the same but nw with 2 db extra attenuatin between the tw Netwrks. Shws the same relatin as in Fig 8, but nw with a smaller size Netwrk, and the Fading margin is increased frm 5 db t db. Shws the same smaller Netwrk but withut the 2 db attenuatin. Fig : Shws the number f succesfull packets frm the Server t the individual statins in the 5 secnds test time. Nte: All simulatin results shw a Ptential Pwer Cntrl cmparisn between CSMA/CA + Ack, 4-WAY LBT and W A VELAN CSMA/CA prtcl. W A VELAN is hwever nt equipped with a Pwer Cntrl facility. Submissin Page 7 By: Wim Diepstraten

18 - dc: EEE P82.-92/76 LLC DRVER u L). MAC Rx R X Rx T X Pwer Lev el Cntrl Thl 7shlcl \ u RADO MODEM (PH Y) \/ Sw Hw Fi g. 3 wreless COMMUNCATON CHANNEL LAYERED ARCHTECTURE Submissin Page 8 By: Wim Diepstraten

19 C/l s::: (J. en en :: ;? ()q () -\ t ':': :E. t! (i)' ' en g, , -- - MAC RADO MODEM Rx-THRhla Dest-ADDR r--l Src-ADDR N\JD -=- TxC":' \ n<vy((){ J -... SERAL DATA TX TxD,...=,. C\> (DATA) una CRC Generu tin rv-----v... CTS TRANSMTTER L TX TxE -= FRAME i\ BUFFER 7. DR VER 4 TBufP ACCESS BUFFTR r-j TX/RXJ r--- CONTROL... Switch MANAGEMENT STATE SOFT\JARE RBufP /-- MACHNE, ""'- Le \ (-BUSY', Dest-ADDR W,-- ra- CRS ',..--- Src-ADDR Rx-STATE-MACHNE ""- N\JD """'" RxD..., A ""'- -. ADDR RECEVER Rx-DESERALZE -...,. X. >.XA RxC, (DATA)... Fil ter : una CRC CHECK RX --.. ""'- rv--v FRAME BUFFER W Silence -L vl J RX-Level Rx Level MEASURE J Fi 9 u 4 wreless MAC+PHYSCAL BLOCK DAGRAM LAYER - -- "... Q.. Q OC S "... "... ="

20 C/l s- 8. Vl '" ::l MAC FRAME STRUCTURE DEST ADDR 6 (, DATA... '"d OQ (D V tr: ':": S t) (n. "C Vl ::l.l -6 db'l -6 db'l S -) SR! r r - FM -2.\\ ; : ;: -2-3 J \ \ -3 4 / / , J J...J : ' Fig: 5 Pwer Cnt" l effect DiQgrQM Q. n => tij ""d QC -' -' \

21 dc: EEE P82.-92/ OJ >. tl :::s::: '-.-/ ::J.....c CJ' ::J '-..c >. en :::s::: '-.-/ ::J.....c CJ) ::J '-..c - 5 POTENTAL OF POWER CONTROL Peer-t-Peer '7/ fl" /- /,,/ i- Pce=2.5 '7-7- }l- -,.. v- v.---- J ---- CSM A/CA + Ack =-- v --r-'" p_ '- '/ - --?( /' \7 /' \7- 'V -i WA "{ LET Pce= Fi g >. 25 en :::s::: '-.-/ 2 ::J.....c CJ' ::J 5 '-..c - 5 /' / '7 v.,-.-:..- ::::-.-l- p_ '7- '? '- v-- 'l- t v /"' p""" L /. /..::::..-._.---r Pce=2.6 l WAVEL AN CS MA/c} Submissin Page 2 By: Wim Diepstraten

22 35 dc: EEE P82.-92/76 POTENTAL OF POWER CONTROL Client-Server... <!) 3 >. 25 CD ::s::: '--" 2 -- :::J....c ' :::J 5 "--..c t-- 5 v- ' /,,,/ h ".. '7/ :, Pce=5.E --:::--l -,., ---- b 'V- - 'V- OS A/CA + Ack >. 25 CD ::s::: '-'"... 2 :::J....c ' :::J 5 "--..c - 5 v-- '7-.-.,../ - i/ t -.. :.-=-- Pce=4.! WA rr LET Fig >. 25 CD ::s::: '-'" 2... :::J.. 5..c ' :::J -..c ,.., - f7._ it-.- '7- v/' p/.._./ '"': t=-'"',.. Pce=6.7 WAEl AN C MA/Cl Submissin Page 22 By: Wim Diepstraten

23 dc: EEE P82.-92/76 35 POTENTAL OF POWER CONTROL Client-Server 2 db Between NW's... 3 >. 25 en '-' 2 -+J :::l a... 5 CTl :::l >. 25 en '--' 2 :::l a... 5 CTl :::l 'V /./ -r 'V Pce==5.6 -,-, e- /. - 'V CSMP /CA + Ack 2 3 "/./..,/:./.L-. Pce= V WAY LBT Fig. [ J 3 >. en 25 '--' 2 :::J a... a> 5 :::J 'V - 'V /. /t 'V Pce= _ WAVEL AN CSMA/CP 2 3 Submissin Page 23 By: Wim Diepstraten

24 dc: EEE P82.-92/76.35 POTENTAL OF POWER CONTROL Client-Server 2 db Between NW's.3,..." 25 >. CD '-'" 2... :J a. CJ' :J... t- 5, >. 25 CD '--' 2... :J a. 5 CJ' :J... t- 'M. 'V!-.. 'il. /. 7 : / Pce=9.7 CSM A/CA + Ack J 'il- - - /._- --,,- /.-/: 4-WAY LET Pce=8.3, Fi g. 9.3,..." >. CD 25 '-'" 2... :J a. CJ' :l... t- 5 5 / /. 'il- V -:i=- /; / J Pce=8., _llii :lii - WAVE AN CSMA/Cl 2.3 Wading Margin db [SMALLER NETWORK! Submissin Page 24 By: Wim Diepstraten

25 dc: EEE P82.-92/76 35 POTENTAL OF POWER CONTROL Client-Server 3,... >, 25 CD '-" 2 :J a..r: ' :J 5....r: - 5./ 'V e v/ t... _/.-_::::: -----_ - Pce=7.2 t-? 'V v 'V v 'V t C$M A/CA + Ack , >, 25 m 2 :J a. 5.r: ' :J....r: t _ v,,/' - / ---- i/ t----- Pce=5. h..., h <7 <7 t WA if LBT , >, 25 m '-" 2 +-' :J a..r: ' :::J 5....r: t- 5 i"...-' r..../ a--- 'V,- ' ji:::-... /'".., 'V_ 7 t"""""" Pce=8. r WAVEL AN CS MA/Cl Fiq. Fading Margin db SMALLER NETWORKJ Submissin Page 25 By: Wim Diepstraten

26 - dc: EEE P82.-92/76 3 POTENTAL FOR POWER CONTROL Client-Server 2 db Between NW's u (f) t.{) "--... (f) "--... (f).;,l u... 2 ;.- -.,... - i A--,.-", :-" -..'.- ",---. t=--'- / / /, /...' /{, / CSMA/ CA + Ack u (f) t.{) "--... U "--... (f)...,.;,l u CL 2 :/' D' if-- " t ;::."'!F"s _--:is,--:- j.-. :; - - / 4-WA Y LBT u (f) t.{) " jja...-"":"""'---=!a+'-+u'-r:r-...:s;:t U " "':" ;,L u CL L-_ '" / '" WAVE AN C MAC -L Fig db Fading Margiij SMALLER NETWORK Submissin Page 26 By: Wim Diepstraten