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ABSTRACT
MUTUAL INTERFERENCE INVESTIGATION OF CEBus and X-10 POWERLINE SIGNALING
by Sajid Pallithotungal
Powerline control signaling using CEBus has great potential towards inexpensive home automation. CEBus transmits at 10 kBps using spread spectrum in the 100-400 kHz band while X-10 sends 60 Bps using bursts of 120 kHz carrier on the power line. However, these two signals may destructively interfere when present simultaneously. X-10 is narrow band and interferes with the CEBus spread spectrum signal. This thesis looks into the mutual interference patterns of Power Line CEBus communication in the presence of
X-10 module signaling and visa versa. The investigation encompasses a series of tests and measurements on a Powerline CEBus-X10 test bed. The test bed allows progressively attenuated signal levels of X-10 to interact with CEBus and vice versa.
Thus, the probability of success of CEBus and X-10 packets were studied at various levels of CEBus and X-10 in absolute as well as in relative terms in the ranges of approximately 0 to 20 dB. In general, the CEBus signal obstructs the X-10 signal. Weak strength X-10 does not have any effect on CEBus, but a weak strength CEBus does have a discernable adverse effect on X-10. For the same levels of attenuation, CEBus packets have a higher probability of survival than X-10, which can be attributed to the processing gain inherent to the CEBus spead spectrum signaling as well as to the lower detection threshold level of CEBus with respect to X-10. However, when a strong X-10 signal interferes with a weak CEBus signal some probability of CEBus packet loss was observed. Simulation studies further illuminated the interference behavior of the CEBus
X-10 cohabitating signals under that scenario. MUTUAL INTERFERENCE INVESTIGATION OF CEBus and X-10 POWERLINE SIGNALING
by Sajid Pallithotungal
A Thesis Submitted to the Faculty of New Jersey Institute of Technology in Partial Fulfillment of the Requirements for the Degree of Master of Science in Telecommunications
Department of Electrical and Computer Engineering
August 1999
APPROVAL PAGE
MUTUAL INTERFERENCE INVESTIGATION OF CEBus and X10 PO MANE SIGNALING
Sajid Pallithotungal
Dr. Constantine N. Manikopoulos. Thesis Advisor Date Associate Professor of Electrical and Computer Engineering New Jersey Institute of Technology
Dr. Yun-Qing Shi. Committee Member Date Associate Professor of Electrical and Computer Engineering New Jersey Institute of Technology
Dr. Dennis Karvelas. Committee Member Date Director MS in Telecommunications New Jersey Institute of Technology BIOGRAPHICAL SKETCH
Author: Sajid Pallithotungal
Degree: Master of Science in Telecommunication
Date: August 1999
Undergraduate and Graduate Education:
• Master of Science Telecommunications New Jersey Institute of Technology, Newark, NJ, 1999
• Bachelor of Science in Electronics Engineering Bombay University, India, 1990
Major: Electrical Engineering This thesis is dedicated to Dr. Homi Jehangir Bhabha ACK OW E GME
e au o wis es o e ess is si ce e a ecia io a g a i u e o is a iso C Ma iko ou os o is co s a su o a e cou ageme oug ou is esea c e wou a so ike o a k is esis commi ee mem e s S i a Ka e as o aki g ime o om ei usy sc e u es o e iew is wo k
i A E O CO E S
C a e age 1 INTRODUCTION 2
1.1 Overview 2 2 CEBUS ARCHITECTURE AND PROTOCOLS 4
2.1 CEBus Architecture 4
2.2 Control Channel Signal Encoding 10
2.3 The CEBus Channel Access 11
2.4 Contention Detection and Resolution 13
2.5 Message Failure and Retransmission 14 3X-10 16
3.1 X-10 Architecture 16
3.2 X-10 Signal Encoding 17
3.3 Theory of Operation 17 4 SIMULATION MODEL 20
4.1 The Simulator 20
4.2 Network Model and Traffic Patterns 21
4.3 Relation between CEBus and X-10 Transmission 22
4.4 Performance Measure and Definitions 24
4.5 Analysis and Discussion Of Simulation Results 25 5 INTERFERENCE INVESTIGATION 26
5.1 Test Bed 26
5.2 Test Scenarios 27
5.3 : Test Measurements and Results 32 CONCLUSION 35 APPENDIX 37 REFERENCES 53
ii
IS O IGU ES
igu e age 2.1 Organization of CEBus 4
3.1 X-10 Messaging Format 15
3.2 X-10 Transmission synchronized to the power line zero crossing 17
3.3 X-10 Message takes 11 cycles 17
3.4 X-10 Full Packet 18
4.1 Relation between Frequency and time in one UST 22
4.2 (a) X-10 transmit 3 1-ms bursts of 120kHz every 16.7 ms and (b) CEBus transmits USTs each of 100microsec continuously 23
5.1 Attenuator-Bridge circuit 26
5.2 CEBus and X-10 transmitter and receiver on the same side of the power strip 27
5.3 X-10 transmitter on one side and CEBus transmitter and receiver on the same side along with X-10 receiver 28
5.4 X-10 transmitter on side and CEBus Transmitter and Receiver on the other side of the power strip along with the X-10 receiver 29
5.5 X-10 transmitter and CEBus Transmitter on one side and both the receivers on the other side of the power strip 30
5.6 Scenario 1:X10 statistics 31
5.7 Scenario 1: CEBus statistics 31
5.8 Scenario 2: X10 statistics 32
5.9 Scenario 2: CEBus statistics 32
5.10 Scenario 3: X 10 statistics 32
5.11 Scenario 3: CEBus statistics 33
5.12 Scenario 4: X10 statistics 34
5.13 Scenario 4: CEBus statistics 34
5.14 Unattenuated X-10 signal 38
5.15 Attenuated X-10 signal 39
viii IS O IGU ES (Co i ue
igu e age 5 1 U a e ua e CE us 5 17 A e ua e CE us 1 5 1 A e ua e CE us sig a (1 9 5 19 A e ua e -1 sig a (1 9 3 5 acke ecei e i e o s o ma i e o e e oa 5 1 Message oug u s o ma i e o e e oa 5 5 o ma i e o e e oa o acke e g o 1 3 5 3 Message oug u s o ma i e o e e oa ( 1 1 oa 7 5 C a e oug u s o ma i e o e e oa 5 5 o age swee a (Sce a io 1 9 5 o age swee a (Sce a io 5 5 7 o age swee a (Sce a io 3 51 5 o age swee a (Sce a io 5
i IS O A ES
a e age
1.1 Major characteristics of the Home Automation Groups 2
1.2 Symbol Duration for PL 8 C A E 1
I O UC IO
1 1 O e iew
Over the past ten years a new industry called "home automation" has been developing.
This industry will create the next generation of consumer appliances. Not only is modem housing becoming more convenient to live in and more energy efficient, but also the primary value added by home automation is the integration of products and services for household use.
In America, several groups have attempted to develop home automation standards. The most focused of these are CEBus, X-10, Smart House, and Echelon. The
EIA (Electronic Industries Association) has taken the lead with the development of the
CEBus, the Consumer Electronic Bus. In 1984, a committee was made up of such major companies as Sony, Philips, Panasonic, General instruments, Mitsubishi, RCA, and
Johnson Controls to develop a standard to facilitate communication between home appliances over various media. The primary goals of the CEBus are, it is profitable which makes it low cost, expandable, ease of operation, use distributed intelligence (have no central computer in order to operate), have an open architecture which means that any product manufacture may produce compatible devices on their own. It follows the
ISO/OSI seven layer network model [1].
X-10 was introduced in 1978. It uses power line carder transmission for system
control. It is a one-way open loop system with limited potential for intelligent home
control [2]. Echelon is similar to CEBus concept. It produced a specialized computer chip
called " O " which allows multiple devices to communicate through any medium. However, the primary difference is such issues as protocol, language and the proprietary
standards (i.e. it is not an open architecture and is owned by the manufacturer) [3]. Smart
1 House is developed by the National Association of HomeBuilders (NAHB). It is especially for new houses where a three multiconductor cable is installed during original construction in place of conventional house wiring. This cabling system combines power, control, telephone, and coaxial conductors and provides a dedicated six-wire bus throughout the house [4]. Table 1.1 shows the major characteristic comparison of home automation groups in the United States.
a e 1 1 Major Characteristic Comparisons of the Home Automation Groups C A E
CE US A C I EC U E A O OCO S
1 CE us A c i ec u e CE us o ows e ISO/OSI se e aye e wo k mo e wi some aye s ei g u as s ow i igu e 1 Eac aye is es o si e o o e as ec o e wo k commu ica io wi eac aye o y a e o a k o e aye s i ec y a o e a e ow i y eaki g e mo e i o we - e i e ieces im eme a io a su o a e g ea y sim i ie
1 1 A ica io aye e ig es e e is e a ica io aye a is es o si e o w a e e use u ima e y sees CE us as e ig es e e e i e w ic is w a e e use wi see ( ecause i ma y cases o e a io wi e a s a e o a o e e ice s e is i g u c io a i y u w a e og amme sees A ica io aye wi a so o i e e ca a i i y o segme o g messages i o a seque ce o s o e acke s a o gua a ee e - o-e message e i e y ese acke s a e a e ow o e owe aye s o a smissio EIA as e i e CA Commo A ica io a guage o a ow e ices o commu ica e i e ige y wi eac o e e mai use o CA i i ia y wi e o co o e a guage as ume ous comma s e i e o u i g e ices o a o immi g u a ow o e i g a c osi g us mo e com ica e ac io s suc as se i g C ese s o es o i g o e e o e comma s I is ac ua y a e i e e e a e a es o co s a s w ic a e ee e i e o e ese e ice ca ego ies comma s ac io a es o ses As ew e ices a e e e o e y ma u ac u es e a es wi e e a e (u e EIA s co o o i c u e ose e ices a a y ew u c io s [5] A ea e is a e o e o o e CA comma o c ea e e A ica io o oco a a U i (A U w ic is e asse o e e wo k aye
3 4
igu e 2. Organization of CEBus
2. .2 a s o , Sessio a ese a io aye s In the CEBus, the transport, session and presentation layers have been omitted to minimize packet length and device complexity. Some of their functions are handled by the application, network, and data link layers.
2. . e wo k aye The network layer is responsible for all the functions described in the OSI reference model except for segmentation and network connections, where segmentation takes place
in the application layer and the flow control of the segments is handled by the network layer. The Network Protocol Data Unit (NPDU) is added to the front of the information 5 ie asse ow y e a ica io e e I e o ms ou i g o U e wee i e e me ia oug ou e s e e a e si i s o e e mi e w ic me ia is o ecei e e acke Se i g a i i e ie esu s i e co es o i g me ium ecei i g e acke (assumi g o e i ge is ese o a s e acke s ac oss me ia e as wo i s e e mi e w e e e acke is o e se usi g oo ou i g i ec y ou i g o i ec o y ou i g wi a eques o a e u I I oo ou i g e acke is se o e e y me ium s eci ie i e es o e ie I i ec o y ou i g e acke is o y se o e me ium w ic os s e es i a io o e?
1 a a i k aye e u c io o e a a i k aye ( is i i e i o wo su aye s e Me ium Access Co o (MAC Su aye a e ogica i k Co o ( C Su aye
ogica i k Co o Su aye ( C e C Su aye o i es e i e ace o e e wo k aye a a mi is e s e a smissio a ece io o Us I ecei es Us w e e agai a ea e is a e e U as a i e o ma a may e o wo y es o se ices u ack ow e ge o ack ow e ge co ec io ess se ices I u ack ow e ge se ice a acke is se i y i e o es a i makes i o e es i a io Ack ow e ge se ices make use o a IACK a e a smissio mec a isms o a smi a acke a ogica i k Co o Su aye a a U i ( U is ge e a e a asse ow o MAC Su aye wi i s associa e co o a ame e s I ack ow e ge se ice is use e C Su aye wai s o e ece io o a IACK a i o e a i es i u i sym o ime i i i ia es a e a smissio o e MAC ame W e a ame is ecei e y e MAC Su aye e U is emo e a asse o e C Su aye e C ea e is e emo e om e U a e emai i g U is asse u o e e wo k aye e e wo k o e e mi e i a yo e e se is a ea y a smi i g W e e e wo k is ee e o e wai s a ce ai amou o ime e o e yi g o a smi o a oi co isio o e s a s y se i g ou a eam e I e eam e su i es i ac e es o e acke is se I a co isio is e ec e a smissio is a o e a e ocess s a s agai
1 5 ysica aye A e owes e e is e ysica aye I is i i e i o su aye s Sym o E co i g Su aye a e ysica su aye is is w e e CE us s g ea es s e g ies si ce se e a i e e me ia a e e i e i e s eci ica io wi e c oice o w ic me ium o use u o e a ia ce esig e A se a a e ysica aye s eci ica io e is s o eac i e e me ium A e aye s a o e e ysica aye a e i e ica ega ess o me ium so e e wo k is me ium i e e e Sig a i g is o e o mos o e me ia y swi c i g e wee a SU E IO a I E IO s a e imes e wee c a ges e e mi e e i o ma io ei g co eye "O e" i as o e "U i Sym o ime" (US " e o" i s as wo US s e -o - ie as ee US s a e -o - acke as ou US s E ac y w a e i es e su e io a i e io s a es e e s o e me ium A so si ce c a ac e i i g commu ica io s ee o a me ium i i s e seco is mea i g ess si ce o e i s a e o i s a e o i e e u a io a a a es a e usua y e i e i e ms o "o e i s e seco " S a is ica y e o e a oug u i i s e seco is a ou wo- i s e a ue o o e i s e seco a e 1 Sym o u a io o e CE us s eci ica io e i es si me ia w ic may e use o ca y e sig a owe i e wis e ai i e o ic coa ia ca e a io eque cy a i a e e Sym o e co i g su aye e ese s ecessa y i e ace o e Me ium Access Co o (MAC aye a e ysica aye o e me ium e sym o s o a ame a e gi e se ia y o e SE Su aye o a smissio a e o e ec io akes ace i is su aye
owe i e ( I is ike y o e e me ium o c oice o mos a ia ces mea o e o i i s a a io s si ce a mos e e y ouse a usi ess i e wo is wi e o e ec ici y Si ce owe i e is suc a a s e i o me wi oise a a sie s e o m is is e s owes o a me ia u s i a e o a ai a a a a e o 1 o e i s e seco wi a US o 1 gs a smissio use a 1 k ca ie o e o e a su e io s a e a e ack o a sig a o a i e io s a e U ike -1 sys ems w ic a smi s o y a e e o c ossi g us a smi s ega ess o e s a e o e AC owe o e i e? e e o e a smissio ca s i ake ace e e i owe is ese some i g a ca e o e wi - 1
I a e o Si g e oom us (S us S us is a a em o a e a si g e a - e emo e a a smi s a a i CE us comma s o o y e C o i e same oom u wi e o e i ge i ace o a smi e S us sig a s o o us o o e o o e me ia i s ou e a e o co o a y CE us-com a i e e ice i c u i g ig s a o e e ouse o e oo o e e ou i e ga age S us uses a 1 -k i a e ca e a u se- osi io sig a i g o a ai a a a a e o 1 o e i s e seco A 5 s u s o I is use o i ica e a a si io om su e io o i e io y usi g us s o u ses e a e emo e s i e is e e 8 a io eque cy us ( us Currently used predominantly in the security industry, RF is another medium that would work well in retrofits. FCC regulations limit the strength of RF transmission, so whole house coverage may be possible without interfering with the neighbors' CEBus appliances.
wis e ai ( us TPBus promises to be the most useful high speed medium in the majority of installations.
Some houses may have extra telephone pairs that could be used in retrofits. TPBus runs
at a data rate of 10,000 one bits per second and uses a + 125mv peak to peak signal.
Similar to SRBus, TPBus uses 50-p.s pulses to indicate transition.
Coa Ca e (C us With the spread of cable TV, many houses are being wired with coax cable for television
distribution. Since, within the house, the TV signal isn't using the entire bandwidth of the
cable, there is plenty of room for adding control information plus high-quality audio and
video to the same cable. CXBus uses the same pulse width modulation used by PLBus,
with a UST of 100 ms, providing a data rate of 10,000 one bit per second.
i e O ics ( O us Fiber Optics is becoming the medium of choice where high data transmission rates and
low noise pickup are important. While some provisions have been made for this medium
in the CEBus protocol definition, very little work has been done on the physical details.
2. .6 aye Sys em Ma ageme ( SM Layer System Management (LSM) is the entity responsible for initializing variables and
processes and for keeping and reporting network status information. The LSM initializes 9 a mai ai s ee - o- ee o oco o eac aye a o i es a i e ace mec a ism e wee o -a ace aye s [1] e aye Sys em Ma ageme is co ce ua y a ace o eac o e aye s a e o ms a ious e wo k a mi is a i e u c io s i e • ese i g aye e i y o a k ow s a e • ea i g a se i g a ame e a ues i i e e su aye • o i yi g i e e su aye s o sig i ica e e s i e aye Sys em Ma ageme o i e o e aye o e o e
2.2 Control Channel Signal Encoding e sig a e co i g o e co o c a e wi e o e u o e o ( u se Wi E co i g usi g e sym o s "1" " " "EO " "EO " ese sym o s a e e co e usi g a swe eque cy ca ie cou e o e owe i e e ca ie wi co sis o a si usoi a wa e o m a is swe i ea y om 3 k o k o 19 cyc es ack o 1 k i o e cyc e e ack o 3 k i 5 cyc es u i g a 1 msec i e a is ca ie swee e io e ese s e s o es sym o ime ("1" o u i sym o ime u i g o ge sym o imes e ca ie swee e ea s o a mu i e o e u i sym o ime[ ] e e co i g o e sym o s wi e e o me usi g e SU E IO a I E IO s a es o e me ium u i g e eam e o io o e CE us message e ese ce o e eque cy swe ca ie o e wi e ese e SU E IO s a e a e a se ce o e ca ie wi e ese e I E IO s a e u i g e o - eam e o io o e message e eque cy swe ca ie co i ua y a smi e a e co es e i e e sym o s y e e si g e ase o e ca ie swee is ca e see c ea y i igu e 3 I SU E IO 1 a SU E IO a e use o e o e i e e ase e sio s o e SU E IO s a e e 1 they are opposite in phase, regardless of the value of the phase. In the Figure SUPERIOR 01 will be used to denote the phase of the carrier transmitted during preamble.
3 e CE us C a e Access The CEBus channel access protocol is a carrier sense multiple access with contention detection and contention resolution CSMA/CDCR. The protocol attempts to avoid contention by delaying a random amount of time after the end of the previous transmission before attempting channel access. Random wait is based on these factors: 1 Deference to other channel traffic in SUPERIOR STATE. 2 Prioritization 3 Round-robin queuing 4 Random start.
3 1 Su e io S a e e e e ce
A node, while transmitting as SUPERIOR state on the medium, will dominate any attempt for the transmission by any other transmitting node in the INFERIOR state. A node with a frame to transmit will defer its transmission until EOP symbol and a minimum of 10 unit symbol times. This mandatory channel quiet time allows an immediate acknowledge or a retransmission be sent without conflict for the channel.
3 io i i a io
Figure 2.4 illustrates the priority and round-robin queuing delays. The EOP symbols defines the end of a previous transmission. 10 unit symbol times must follow each EOP before any new transmission can begin. Following these 10 unit symbol times is a slot of eig u i sym o imes o ig io i y a smissio s O e a i g wi e as ou u i sym o imes o a s o is a s o ese e o s a a io i y a smissio s i a y o e a i g wi e s a a io i y is a s o ese e o e e e io i y is sc eme a ows o es wi ig e io i y ames o sei e e c a e e o e o es wi owe io i y ames
2. . Queui g a ou o i Sc e u i g e use o e ou - o i sc eme wi i e same io i y e e e su es a e co e i g o es a e equa o o u i y o access e c a e Wi i eac o e eig u i sym o ime io i y s o s a e wo su i isio s ou u i sym o imes eac o u queue a queue a smissio s
Queue S a e O ce a a smi i g o e com e es a a smissio success u y e o e wi e ace i e queue s a e om a u queue s a e e e ec o ei g i e queui g s a e is o e ea e y e e c a e access o a u queue o es a e same io i y e e w ic a e o ye ee a e o a smi a message I e queue o e co i ms a o o e u queue o es a em o se a message u i g e 4 US o i s queue s a e s e ay i may a em o se a message as ee e
U queue S a e is s a e occu s i o e o e o owi g wo ci cums a ces I I i as o message o se a e me ium is se se i e o e ma imum c a e access ime ( US s I o e o e queue o es com e e a a smissio u i g e o owi g US s o s 2 2. .4 a omi a io Because more than one node may be in the same priority level and queuing state, the probability of contention still exists. A random delay of either 0, 1, 2, or 3 USTs is used for the control of each node's transmission start time, which results in reduction of contention probability during each of the priority queuing time slots (Figure 2.4 b). By this method, the channel throughput can be improved significantly.
2.4 Co e io e ec io a eso u io In the earlier section, steps taken to avoid contention were discussed. However, two or more nodes may still attempt to transmit a frame during the same time interval. To ensure reliable communication between Data Link Layers, a means of detecting contention and resolving in favor of one node is still required.
The use of SUPERIOR and INFERIOR states on the transmission medium enables contention detection. Any node, which senses a SUPERIOR state while sending an INFERIOR state, will defer its transmission. It becomes aware of the presence of one or more other transmitting nodes.
Contention will normally occur at the beginning of the transmission. Therefore, the Preamble, positioned at the beginning of the frame, serves to provide signal pattern and to shield the information from being lost during contention. The Preamble field is made up of a random sequence of bits, which is usually a function of the node address
and the number of ONE symbols already transmitted by the node [1 ].
Contention resolution involves the simultaneous transmission of more than one Preamble.
Since the node which drops into the INFERIOR state first is removed from contention,
the wining node is able to transmit free of contention. That is, contention has to be
resolved during the Preamble. The Preamble carries no information and its bits are not
included in the calculation of the checksum delivery of the frame will be successful. 13
A collision refers to overlapping transmissions after the Preamble. Although conflict over the channel during any part of the frame after the Preamble constitutes a breakdown of the channel access method, a sending node will abort its transmission and defer during any part of its frame. This will result in the reception of a bad packet.
Therefore, a retransmission will be required.
2.5 Message Failure and Retransmission
Message failure occurs when the received frame does not appear to be valid to the receiving node. If all required fields of the frame are not received properly, the frame will be rejected as being a fragment. In addition, a packet could be rejected if the checksum performed at the receiving node indicates faulty data. Noise on the channel and conflicting node transmissions could cause these message failures. Therefore a retransmission may be needed to guarantee a successful delivery. To increase the reliability of the network, an Immediate Acknowledgment (JACK) and retransmission mechanism could be used.
2.5.1 Immediate Acknowledgment (JACK)
The Immediate Acknowledgment mechanism enables the transmitting node to determine the success or failure across a single medium. It is invoked when the Network Layer requests acknowledged connectionless service.
When a message is received without errors, and an acknowledgment is requested, the receiving node forms an JACK frame. The TACK frame is sent out onto the local medium
within 2 USTs of the end of the LOP symbol of the originating frame. By immediately
responding within the minimum channel access time (10 UST), the receiving node is
assured of sending the JACK without having to contend for the channel. 14
2.5.2 Retransmission
If a negative acknowledgment is received, or if no IACK is received within 6 USTs at the originating node, then the originating node will begin a retransmission. Immediate channel access is achieved by beginning the retransmission before the minimum channel access time elapsed. All nodes counting the minimum wait time will hear the retransmission and defer to it. C A E 3
-1
3 1 0 A c i ec u e -1 was i o uce i 197 I uses owe i e ca ie a smissio o sys em co o I is imi i e a oes o i e i eg a e e wo k I s o uc s o o commu ica e o a -way asis I ese y ocuses as mo u a a -o y e e ices w ic a e esig e o o e u c io s o o /o a e e co o o esis i e a eac i e oa s e -1 o e a io is ase o 1 e e co es a 3 um e co es a a e com i e i o a si g e comma acke O e 3 um e co es 1 e ese s u i a ess a e emai i g 1 e ese s comma s ike o o e c A e e co e is use o i e i y w ic g ou o u i s wi ecei e comma s Com i i g a e e co e wi a u i a ess esu s i 5 ossi e a esses o -1 u i s e s uc u e o e co e is sim e e e e co e ece es e um e co e w ic makes i e i s us a s a seque ce o wo i s o a o a o e e e i s [ ] ( igu e 3 1
4
igu e . -1 Message o ma
e u i s a e i s a esse y se i g e e e co e a u i co e e o e a io e s e u i s o e ec a comma Se e a u i s o e same e e co e ca e a esse simu a eous y y se i g mu i e u i a esses e o e o e comma e a comma o se ies o comma s a e se o e u i s e u i s emem e 6 that they have been selected even after receiving a command, so as long as no new
addresses are send the same units will receive and carry out subsequent commands.
.2 0 Sig a E co i g X-10 transmission denotes "1" bits with three 1-ms burst of 120-KHz signal and "0" bits
with the lack of this signal. One bit is transmitted at each zero crossing of the 60 Hz
power line frequency. Each bit is transmitted plus its complement side by side. This
aspect is true for all letter code and unit code data bits. The start code uses a different
format. It is always the same two cycles sequence 1110. The transmitter releases a burst
at its own zero crossing, then sends it again 60 ° later: the second burst coincides with the
zero crossing of the third phase. Then another burst is sent 120 ° from the first, which
corresponds with the zero crossing of the second phase. This is shown in Figure 3.2.
. eo y o O e a io All receivers are looking for a "start code" before anything else. This start code is defined
as 1110. For the receiver to consider accepting a full transmission it must first receive the
1110 in 4 adjoining, consecutive zero crossings. Once the start code has been received,
the next four true bits of data are compared to the letter code of the receiver's address.
Should the letter code not match, all further data will be ignored until the receiver detects
another start code. If the letter code match, the next five true bits of data are compared to
the number code. When both the letter and number codes match, the receiver will await a
function code. Time wise, this sequence, so far takes 11 cycles as shown in Figure 3.3
[6]. For reliable transmission this series is sent twice. The data string for the command
portion of the transmission also begins with a start code. After that, the code is again
checked for true complement relationships. 17
Figure 3.2 a) X-10 transmissions are synchronized to the power line zero crossings. b) during the next half cycle, c) A 0 bit is the opposite, with the bursts occurring during the second half of the cycle, d) Every transmission begins with a unique start code, which lasts two full AC cycles.
22 HALF CYCLES FOR A COMPLETE MESSAGE
Figure 3.3 X-10 Message takes 11 cycles
A "1" data bit is represented by three 1-ms bursts of 120 kHz signals, followed by silence
letter code comparison, and if the next 5 bits indicate that this code is the command for
Figure 3.4 X-10 Full Packet
"ON", then the receiver will switch on. A pause of 3 power line cycles is inserted between the identification data and function data. This means that a full and complete transmission consists of 47 cycles, or .7833 seconds [7]. (Figure 3.4) C A E
SIMU A IO MO E
1 e Simu a o e simu a o is ie y esc i e i is c a e e e i i io s w ic go e e a a ysis a iscussio o e simu a io esu s a e i o uce e e e simu a o o e sys em a o oco mo e o e e e ime was w i e i C a guage usi g C i a y u c io s o i e y A S [ ] A S is a co igu a e simu a o esig e o mo e commu ica io e wo ks I ca e mo i ie o simu a e e CE us a c i ec u e o ose i e EIA s a a e ease i Oc o e 199 [1] a e -1 a c i ec u e e a i u es o a commu ica io e wo k s eci ie y A S ca e i i e i o wo ca ego ies e i s ca ego y co ai s s a ic e eme s o e am e sys em a c i ec u e a o o ogy e seco ca ego y co ai s y amic a i u es a esc i e e em o a e a io o e mo e e sys em e e am e a ic a e s a e o ma ce measu es e simu a io i o es wo asks sys em a o oco mo e i g a e wo k co igu a io e e a e ou og am i es ee e o i e ace A S a e CE us e wo k ey a e o oco c o oco o io s a e i u a a i e e o oco c i e s eci ies e e ecu a e a o e o oco s eci ica io a u c io s w ic e ese o oco ocess e ecu e y s a io s ( o es I a so co ai s wo o e su ou i es a mus e i c u e wi e o oco mo u e e i s i o oco w ic i i ia i e e simu a o a ea s e a ues o e g o a o oco -s eci ic a ame e s e seco ou o oco w ic co ai s e ou u esu s a e o oco - s eci ic i u a ame e s e e i i io s o o oco -s eci ic sym o ic co s a s a e ec a a io s o o -s a a s a io a i u es a e ou i e o oco i e e o io s i e co ai s e oca o io s suc as ecisio o um e s e y e o o a ia es e ese i g o a smissio a es e e g o a i io a
19 20 i o ma io ca ie y messages a acke s e y e o a smissio i k a e um e o mome s o e ca cu a e o s a a s a is ics e i u a a i e co ai s e ime sec io a e co igu a io sec io w ic e i e e ack o e o e e wo k I co ai s e um e o s a io s e um e o o s e s a io e i k um e a y e e o a um e o o s a ei a smissio a es e is a ce ma i esc i i g e is a ce e wee e o es e um e o messages e message e g e mea i e a i a ime e um e o se e s a ecei e s a o io a oo g ou o oa cas y e messages e i a segme co sis s o e e i co i io s ame y e o a um e o messages o e ge e a e e simu a io ime a e C U ime imi
4.2 e wo k Mo e a a ic a e s e owe i e ( o CE us o e a es a a a a a e o 1 K /s e assum io s use o e e o e mo e a e as o ows • I e e e oisso a i a ocess a eac o e wi a e acke s/sec • e acke e g o CE us a e e o e ia y is i u e wi mea i s • e e - o-e o aga io e ay is ig o e si ce i is muc sma e a e acke a smissio ime; • e i a e o e c a e is c 1 O E i s/sec • e e a e M o es o e e wo k e o a um e o o es M u i i e i e simu a io is 1 e e a e 9 o es o -1 a 9 o es o CE us o w ic ee o es eac o IG S A A a E E E io i y c asses A CE us ge e a e messages a e symme ic o eac io i y c ass us eac o e 9 o es em oy e same a es(e g same a i a ime o ge access o e me ium e CE us o ma i e o e e oa G w ic is e i e as e o a o e e oa o ma i e y e c a e ca aci y C is ca cu a e usi g e o owi g 1 1
C length for the three types of messages, respectively. In this simulation study, packet length of 300 bits have been considered for the CEBus packets. The packet arrival rates for all three priorities are equal. Furthermore, the following studies involve equal message and packet length to reveal the queuing time effect. The X-10 normalized offered load is calculated using the following relationship:
x C where ;( λx stands for the arriving rate of packets, L— is the packet length and is equal to
44 bits, and Cx is the bit rate on the channel and is equal to of 60 bits/sec. All the simulations were run for a total of 5,000 messages.
4.3 Relation between CEBus and X-10 Transmission
CEBus powerline uses bursts of 120 kHz signal, know as the SUPERIOR state to send bits of information, similar to the way X-10 works. CEBus uses a swept frequency carrier coupled to the power line. The carrier will consists of a sinusoidal waveform that will beswept linearly from 203 kHz to 400 kHz for 19 cycles, back to 100 kHz in one cycle, then back to 203 kHz in 5 cycles during a 100~sec interval. The relation between time
and frequency during one UST is shown in Figure 4.1. In an effort to estimate the probability of interference, p, between CEBus and X-10 during one UST, we assumed the
following The presence of a filter of Q = 5. Then the probability of frequency being in the
range of 120 kHz + 12 kHz during one UST is calculated. 22
cycles
Figure 4.1 e a io e wee eque cy a ime o 1 US e ese ce o e i e wi eg a e is ca cu a e o a i i y o i e e e ce e o us ess o s ea s ec um w ic a ows co si e a e eg a a io e o e a e o is
5/( 3-1 + 1( -1 = = 9 5
ec a e So we assume i o e i e o e o 1 -3 I ou e e ime we use a CE us acke o 3 US s Si ce o e US akes 1 sec e e w o e acke wi ake 3 msec u i g is 3 msec -1 I o e mi iseco CE us a smi s 1 US s o es ima e e o a i i y o e o OE i case o a co isio e wee CE us a -1 acke s we may w i e OE = 1 - E w e e E is e o a i i y o o e o E = (1- w e e is e um e o US s a co i es wi e 1 k u s s o -1 = E = (1- = (1 - ® = (1- 1 = 9 POE = I - E = 1 - 9 = e e o e e o a i i y o e o i CE us acke i case o co isio wi -1 acke is ake as % i ou e e ime s 23
3 ms ( Figure 4.2 (a) X-10 transmits 3 1-ms bursts of 120 kHz every power line cycle or every 16.7 ms (b) CEBus transmit USTs each of 100psec continuously bursts * 10 USTs per burst = 60, and p is the probability of interference, which was assumed 10 -3
4.4 Performance Measure and Definitions
The traffic generator in LANSF generates the packets and places them in station's queue.
Once a packet is in a queue it waits until it reaches the top of the queue [9J. When a packet is on top of its queue it is ready to be transmitted. The time spent in the queue
awaiting transmission is called the queuing time. There are two types of delays. They are
message delay and packet delay. In addition, we can consider two different types of
throughput. Namely, channel throughput and message throughput.
Message delay which was measured as the time elapsed from the moment the message
was queued at the sending node to the moment the entire message is successfully
received at the destination (including the message queuing time) [101
Packet Delay was measured, as the time elapsing from the time the packet became ready
to be transmitted to the moment it is successfully received at its destination Message
throughput was calculated as the ratio of the total number of bits received at the
destination address to the number of bits generated at the source. 24 C a e oug u was measured as the ratio of the total number of information bits successfully transmitted through the link to the simulation time. This sometimes is also referred to as effective throughput of a link, in that it includes not only the bits that were received on the link, but also the bits that were successfully relayed to some other link.
4. A a ysis a iscussio O Simu a io esu s
4. . CE us e o ma ce i e ese ce o 0 Mo u es (a Message oug u s oa The message throughput for the IG , STANDARD and DEFERRED priorities. It is clearly seen that the throughput starts to decrease when the load rises to 2, 0.85, and 0.6 for the IG , STANDARD and DEFERRED priorities respectively, in agreement with the corresponding observations for message delays.
( C a e oug u s oa The channel throughput vs. normalized offered load. It is seen the channel throughput
increases as the load increase, until it reaches a maximum of 0.6, 0.81, and 0.88 for 100
USTs, 300 USTs, and 540 USTs, respectively.
(c um e o acke s ecei e i E o The number of packets received in error increases as the number of X-10 packets
transmitted on the channel increases. However, it was found out to be less than 2%. C A E 5
I E E E CE I ES IGA IO
5 1 es e
A test was setup to study the interference pattern and the probability of successful transmission of CEBus and X-10 packets under different scenarios. The test bed is as shown in the figure 5.2
The test bed consists of the following components
• CE us a smi e Transmits 32 byte long packets (test kit), which could be
interfaced with an ASCII terminal to control the device
• CE us ecei e Used to receive the transmitter CEBus signal
• -1 a smi e Used to generate X-10 signals.
• -1 ecei e connected to a lamp, the successful transmission of a X-10 signal is
judged by counting the number of times the lamp switches on and off.
• a ia e A e ua o i ge Ci cui This bridge circuit determines load that needs
to be applied between the two isolated power strips. In our calculation we used 20,
10, 5, 2 and 1 dB attenuation. However the graphs are plotted with the actual
observed attenuation.
• i e i e To isolate any noise or interference from the regular power sockets
• S ec um A a y e a Osci osco e to record all the voltage levels
• A e ua o i ge The attenuator provides from 0 to 101 dB of signal frequency
attenuation, in 1 dB steps, between the power strips and is designed to match a 20
ohm load. Placing 20 ohm resistive loads on each power strip allows the line
impedance "seen" by the device under test (DUT) to be 10 ohms, per the CEBus test
specification
5 26
5..2 Test Scenarios Four different test scenarios were devised. Each scenario having different locations of the X-10 transmitter and receivers along with the CEBus transmitter and receiver. The unique combination of these scenario gave us a very good understanding of the X-10 and CEBus signals when they interfere with each other.
Figure 5.1 Attenuator-Bridge circuit
The test scenarios are four
1. CEBus transmitter and receiver one side of the power strip , X-10 transmitter and receiver both on the other power strip. This is as shown in the figure 5.2
2. CEBus transmitter, receiver, and X-10 receiver on one side of the power strip , X-10 transmitter one the other side. This is as shown in the figure 5.3 3. X-10 transmitter, receiver, and CEBus receiver on one side of the power strip, CEBus
transmitter one the other side. This is as shown in the figure 54 7
4. X-10 and CEBus transmitter on one side of the power strip and receivers on the other
side. This is as shown in the figure 5.5 9 30
Sce a io 4
MEME I K q-A IMIMME ESMMESMEMME i- aiEE K
CE us Sig a Ge e a o
[
1 Sig a ecei e
CE us a smi e
S ec um A a y e
i e i e i e i e
Osci osco e a ia e A e ua o i ge ci cui
O m O m oa oa
1 Sig a a smi e 1 Sig a A a y e
1 Sig a Ge e a o CE us Sig a ecei e
owe -s i owe -s i
Figure 5.5 X-10 transmitter and CEBus Transmitter on one side and both the receivers on the other side of the power strip . es Measu eme s a esu s The voltage levels for all the different attenuation levels levels were measured and printed directly from the oscilloscope. All the plots for the 20db voltage readings are
available in the Appendix. The sweeps for all the values of 20db are also attached to the
Appendix. The plots for the success rate of X-10 and CEBus for all the four scenarios are as shown below. 3 33 34
The test bench was setup with extreme caution since most of the part of the circuit carried live AC Power. The X-10 receiver was a 20-Watts lamp, which would toggle between the ON/OFF State, every time an X-10 signal is generated. The probability of success of X-10 was measured by sending a fixed count of X-10 signal and then counting the number of times the lamp would switch ON and OFF.
The CEBus signal was generated using Intellion's (company specializing in the manufacture of devices, which controls equipment using Powerline as a medium of communication) CEBus test kit. The test kit is intelligent enough to feed the packet statistics to a PC using the serial port, which was then latter analysed. C A E
CO C USIO The study looked into the behavioral pattern of CEBus an d X-10 for different levels of
attenuation, the probability of success of CEBus and X-10 packets were studied. The
voltage levels and combined characteristics of both the waveforms were looked into.
Following are the conclusions from the test bed and the simulation studies done • Weak strength X-10 does not have any effect on CEBus, but a weak strength CEBus does have a discernable adverse effect on X-10. • For the same levels of attenuation, CEBus packets have a higher probability of survival than X-10, which can be attributed to the processing gain inherent to the CEBus speed spectrum signaling as well as to the lower detection threshold level of CEBus with respect to X-10. • However, when a strong X-10 signal interferes with a weak CEBus signal some probability of CEBus packet loss was observed.
Simulation studies further illuminated the interference behavior of the CEBus X-10 cohabitating signals under that scenario.
• Overall. CEBus network has been confirmed to perform well in terms of delays and message throughput in the presence of X-10 modules over the practical range of
normalized offered load.
• At high loads, substantial performance differences may occur, especially for DEFERRED and X-10, where their message throughput approaches zero, and only
HIGH priority packets get a chance to transmit.
• As the number of X-10 packets transmitted on the channel increases, the CEBus experience slightly higher delays. This is due to the fact that X-10 are much slower
than CEBus. CEBus transmit at rates of 10,000 one bits per second while X-10
35 36 • a smi s a a e o o e i a eac e o c ossi g o e owe i e eque cy owe e a ig oa s e -1 message oug u ec eases as ica y a oac i g e o a a e o e ec o e CE us e o ma ce A E I Graphs from the simulation results and from the test bench are listed here. The graphs from the test bench show the waveform as seen on the Oscilloscope and the Spectrum
Analyzer.
37 ek S ( 2. 0 s 4 Acqs
A . 2 6.8 . s eca g: 26 .6 s Wa e o m
C k— k .8 om i e
C Am i .2
w sig ã am i u e C eq • 6 . 8608k ow sig a • am i u e EU 5 M 20.0 s: C 00m e: s iki 6g o esas e eci: , e e e eca W Sa e W m o ma i e o e a i e s O I e a U i i ies
Figure 5.14 Unattenuated X-10 signal ek S o 1 MS/s Acsq [ I Se ec Measu eme
e io
eque cy
• ow osi i e eso u io Wi C é i • 121.2121kHz. ega i e ow M eso u io . . . . 00m M 0.0 s C i 00m . —mo e— o
e ec ig — ow e e e ce emo e Ga i g Se u S a s o Meas . i Meas m O e e s o C I is og am
igu e . Attenuated X-10 signal ek o 00kSis 262 A qs
eca Wa e o m
C k— k . 6 6( 2 om i e
Am .68 .,
( sa e a e eca W i Sa e W m I e e e Si g e Seq o ma i e o e C i e s O I e a U i i ies
Figure 5.16 Unattenuated CEBus ek 1 M S/s 2 Acqs
Se ec Measu eme
e io _ eque cy
osi i e Wi
ega i e Wi
M 0.0 as C i 880m —mö e o
e ec g — ow e e e ce emo e Ga i g Se u S a s o Meas •m i Meas m O e e s o CI? is og am
Figure 5.17 Attenuated CEBus ek S o 1 kS s Acqs I eca Wa e o m
e—c— a I om i e
C i oom 00 s. C 0 .
si om . : . Au osa e W Sa e W m e e e Si g e Seq o ma i e e e s U i i ies . o e O ea s ee
Figure 5.18 Attenuated CEBus signal (18.9dB) e k S o 00kS s 33 Au]
eca Wa e o m
eca om i e
• .00 : 20. . e • • • u osa e sa e eca Sa e W m I e e e i e Si g e See o ma U i i ies o e e e s O Fpreadshee‘
igu e . Attenuated X-10 signal (18.9dB) 44 40 US s acke s
Message oug u .2
0.8 -- IG 0.6 S A A E E E 0.4
0.2
0 2 4 o ma i e O e e oa
Figure 5.21 Message oug u s o ma i e O e e oa o .2 0 oa C a e oug u
- - +- - -
-
---- 1 US s
3 - US s
5 US s
I I I_ _ _ _1_1_ I I _ I_ 1 I 0.0 0. 0 o ma i e O e e oa Figure 5.22 C a e oug u s o ma i e O e e oa o acke e g o 00, 00, a 40 US s 00 US s acke s
Message oug u
----- IG S A A E E E
I 0. . 2 2. . o ma i e O e e oa Figure 5.23 Message oug u s. o ma i e O e e oa o . 0 oa C a e oug u
+ 1±
1 US s 3 Q US s 5 US
1__I 111111 1 1 1 I I i 0. 0 o ma i e O e e oa igu e .24 C a e oug u s o ma i e O e e oa o acke e g o 00, 00, a 40 US s Sce a io o: 20 a e ua io
0 2 20 0 Se ies E . 0 20 eque cy i K
Figure 5.25 o age swee a (Sce a io 1) Figure 5.26 o age swee a (Sce a io Sce a io : A e ua io 20
2 20 gi 0 a 0 , • Se ies : 6
E 0 20 2 eque cy i K
Figure 5.27 Voltage sweep at 20db (Scenario 3) Sce a io 4: A e ua io 20
2
20
Se ies I
0 0 00 200 00 400 00 600 eque cy i K
Figure 5.28 o age swee a (Sce a io E E E CES
1. The Electronic Industries Association's, EIA Home Automation System (CEBus), EIA Interium Standard, October 1992.
2. Davidson, K. "CEBus: Anew Standard in Home Automation," Circuit Cellar Ink; Aug./Sep. 1989, pp. 40-52.
3. Davidson, K. "Echelon's Local Operating Network," Circuit Cellar Ink; June/July 1991.
4. Stauffer, H. B. "Smart Enabling System for Home Automation," IEEE Transaction on Consumer Electronics, Vol. 37, No.2, May 1991.
5. Fisher, J. "Switched-On CEBus: A CAL Interpreter," The Computer Applications Journal, Feb. 1993, pp. 24-31.
6. Zarr, R. "Add a Serial X-10 Interface to your PC," The Computer Applications Journal, Issue #24, Jan. 1994.
7. Advanced Control Technologies Inc. (ACT), PowerLine Control Components, Reference Manual,
8. Gburzynski, and P. Rudnicki, The LANSF Protocol Modeling Environment, Dept. of Computing Science, University of Alberta, Edmonton, Alberta, Canada, 1991.
9. Pan, M and C. N. Manikopoulos, "Investigation of the PL Cebus Performance With and without Acknowledgment," Master's Thesis, Department of Electrical Engineering, New Jersey Institute of Technology, Newark, NJ, Oct. 1993.
10. Parkkam, S. R., and C. N. Manikopoulos, "Performance Evaluation of the Consumer Electronic Bus," IEEE Transaction on Consumer Electronics, Vol. 36, No.4, Nov. 1990, pp. 949-953.
11. Davidson, K. "CEBus Update," Circut Cellar Ink; Building Automation Special #I84, pp. 2-10.
53