The selectivity method of the best signal from hybrid network of 80211 and 80216.doc

精品论文the selectivity method of the best signal from hybrid network of 802.11 and 802.16jean-baptiste yamindi， wu muqingbroadband communication network laboratory，beijing university of posts andtelecommunications，beijing (100876)e-mail:jbyamindiyahoo.fr；abstractrecently the combination technology of two different networks 802.11 and 802.16 as theheterogeneous network became more and more interested for wireless communication and providing the best coverage network and this new technology is more advantageous in the physical layer with high bandwidth coverage for different transmissions of signals receiving by the mobile802.11/802.16. in this paper we propose the new method of how to select the best signal coming from 802.11 and 802.16 without interference. the model system of wimax 802.16 and wlan802.11coverage extension network with the first consideration of just one wimax bs and one wlan ap from which the mobile receiver receives the different signals, and the second with the diversity of wimax bs and wlan aps and the technique of selectivity of the best signal basedon measurement and comparison.keywords: selectivity, signal, transmission, receiver, access point (ap)，base station(bs), 802.11 and 802.161. introductionreceiving the best signal anywhere at anytime without interference is the key research topic for successful wireless communication technology nowadays.the hybrid network of wimax and wlan network for its best bandwidth level efficiency and the choice for ofdm as transmission technique are becoming more popular for the new technology.many different authors are interested in the approaching of signal processing in different ways. in 1, the author proposedan approach of signal processing methods for interception of direct-sequence spread-spectrum signals of performance of detectors. in 4 proposed the mathematical method based on stochastic comparisons of markov chains in order to compute the mobile network performance measures and 5 described the new method for the exploitation of noisy correlation in multiple signal receiverwe propose the new method that focused on selectivity of the best signal from 802.11/ 802.16 heterogeneous network with analytical technique for model strategy based on probability theory to obtain one best signal performance measurement without interference the rest of this paper is organized as follows: in section 2 overview of the phy layer of 802.16 and 802.11section 3model system description of network section 4 performance analysis, section 5 the simulation result and finally, section 6 shows the conclusion .2. overview of the phy layer 802.16 and 802.112.1 overview the wimax phy layera) the preliminaries description of application wimax and wlanthe worldwide interoperability for microwave access (wimax)was approved as theieee 802.16 standards in 2001.- 10 -we have estimation for the application that requires the network combination of eee802.16/wimax and wlan, the network which is called heterogeneous network. in both types of near-los and nlos can be operational with the frequencies around 28 ghz, with the rain cell diameter of approximately 2400 meters on cell sector size with the specified frequency reuse plan. in the near future; december 2009 the ieee 802.16m standard technology; which operates on the high advanced air interface and flexible mobility with transmission of raw data speed of 100mbit/s for mobile applications and 1 gbit/s for fixed applications, cellular, macro and micro cell coverage, broadband services with the frequency range of more higher than 20 mhz, will be defined and is expected to be approve by march 2010.b) the phy layer of wimaxthe phy layer of wimax using the orthogonal frequency-division multiple access (ofdma) frame structure in the time division duplex (tdd) mode on the same frequency band is playing the main role for its best wireless transmission with a higher data rate.these switching transmission modes with the update of time system, frequency, and transmission power are supported by the multiple-input multiple-output (mimo) and the mesh network topology using five service classes such as unsolicited grant service, real-time polling service, non-real-time polling service, extended real-time polling service and the best effort service for the wireless transmission technology of ofdm systems for a broadband signal selectivity.definitely to receive a good quality of signal, the wireless link between a bs and an ss depends on the channel fading and interference conditions. through adaptive modulation and coding (amc) the radio transceiver is able to adjust the transmission rate according to channel quality, that is, the signal-to-noise ratio (snr) at the receiver.2.2 wlan overview and the phy layer of 802.11the wireless local area network (wlan) physical layer is the orthogonal frequency division multiplexing (ofdm) schemes were originally defined in 802.11a phy at 5 ghz supporting 8 different phy modes from 6 to 54 mbps. it designed for the network with the traffic data frame, that each data frame has a 1500-octet long payload.each station of wlan has at least a link to the access point (ap) to be able to connect to the basic service set (bss), which is the combination of the extensions of mac and phy layer to become the central device for other stations of a wlan that we call it the access point (ap).the wireless single-hop network stations send and receive frames via the ap, and the ap operates as relay between them. the source-destination path goes through a home access link, which is a 512kbps cable modem, and the receiver is connected to that link via a wireless channel. the wlan ap array is a set of access points (aps) that are located in the same physical location and operate with different frequencies for the improvement of the acceptance and tolerance of the wireless access networks. the selection of the best peer connection assures the transmission rates of the mobile users. the most recent 802.11n operates with data rates transmission up to 600 mb/s for the channels between 20mhz and 40mhz and with transmission power inferior to 100mwfurther,wlansper-frameoverheadsuchasthephysicallayerconvergence procedure( plcp) header, ack, request to-send (rts), clear to send (cts), etc., can be quite significant percentage-wise when the payload size is small. moreover, a wlan set-up may choose to enable or disable rts/cts, to enable or disable fragmentation.2.3 power control of bs and mobile userin this section we present the main key of the good transmission success by the power control of the bs or ap and the measure performance.the bs can be very operational by assuming the main responsibility of the transmission of signal according to power measurements of the received burst signal. its shall not produce an effective isotropic radiated power (eirp) spectral density exceeding either more than 28.5 db mi/mhz or local regulatory requirements. the power control depends on the distance between the bs and the mobile user. if the distance is so long the power attenuation requires the rf power to be amplified with different burst profiles and to adjust again level of the maximum power spectral density not to exceed more than 39.5 db mi/mhz. the power that the mobile user or bss shall operate is specified in the following sub-clause.3. system module description of networkin this section, we describe the model system of wimax and wlan coverage extension network. for the best understanding of our model, let us firstconsider just one wimax bs and one wlan ap from which the mobile receiver receives the different signals, and the second with the diversity of wimax bs and wlan aps and the technique of selectivity of the best signal. we assume that the coverage area of an ieee 802.16/wimax bs is larger than that of a wlan access point (ap) or cellular bs, the bandwidth per area becomes limited. our most important goal of wireless technology is getting best signal from the receiver with elimination of the interference,3.1 the model system with one wlan access point one and wimax bsfigure 1 the mobile receiver signal from 802.11 and 802.16 networkin a simple single-ended scheme in the fig 1, the receiver operates by comparing the signal on each path to reference threshold levels. the practical single-ended systems often include reference signals transmitted along the bus topology to provide some common-mode noise. in case of the mobile receiver receives only one best signal from 802.16 selected or one best from 802.11network by the in put 802.11/ 802.16. s1 s2s1 s2s s1 1figure 2 the balance machine located in the mobile signal receiver from 802.11 and 802.16the signal that the mobile 802.11/ 802.16 receives depends on the distance from the base station or ap to the mobile 802.11/ 802.16, and the mobile 802.11/ 802.16 signal receiver includes a balance machine that used to compare the best signal come from 802.11 and 802.16.figure 3 the mobile receiver balance machine for selectivity of the best signal from 802.11 ap or 802.16 bsthe balance machine has an indicator that indicates the best signal that come from 802.11 apor 802.16 bs and the selected signal will transmit to the out put of the mobile signal receiver.the balance machine choose the best signal according to the probability of selectivity and for the better signal the indicator reads 1 and the signal will be in active mode in the mobile signal receiver, else the machine indicator reads 0 and the signal will be in sleeping mode in the mobile signal receiver. when distance between the user and the base station changes because of the movement of the user, the machine is still comparing for the best signal according to the distance or the power transmission.the problem here is that what happen if two of transmitted signals are identical? in this case the signal interference problem will arise.the machine can resolve this interference challenge according to the balance machine instruction by indicating to only one best signal either from802.11 or from 802.16 according to the probability of decision to choose one from two.the decision made by the balance machine in choosing one best signal from the two helps to eliminate the interference.3.2 the model system with multi signals from wimax bs and wlan apsfigure 4 the mobile multi-signal receiver from wimax bs and wlan aps in coverage networkwe have the following analysis for the situation of multi-signals from many base stations of802.16 and many aps of 802.11.let us consider j number of the 802.16 base stations that the mobile receiver received j different signals and i number ofaps of 802.11. in general i j.figure 5 the mobile multi-signal receiver & the signal selective machine.the process of selectivity of the best signal is described as follows.at the beginning the pre final selected signal is getting into the pre final-selection machine for the selection of the best signal that will be ranked from up to down by the machine (from strong to weak signal order) from different signals of each network i.e. from 802.16 signals or 802.11 signals. the signals is then placed from up to-down rows order by the pre final-selection machine according to the signal strength and power, the signal at the most upper row mean the best signal and the signal at the most bottom mean the weakest signal of all. after the strong best signal is selected by the pre final-selection machine from either side of 802.16 and 802.11, then the two best signals one from each are getting to the selection machine for final selection process.when the machine compares and gets one strong signal from one of the two chosen signals selected by the pre final machine earlier, then it picks the best signal. but what will happen if twoof these signals from either side are identical? how the machine selects the good signal?during this case the balance machine compares the second most upper signals from either side of the up-down rows that are selected by the pre final selection machine. this process continues until the machine gets the best signal than the other if in case these second row signals are also identical to each other.the process of selecting a good signal will be held with time and if the user moves, then the selection process is repeating again, starting from the beginning.4. performance analysis4.1 problem formulationlet us consider the total of signals siand nisjnoise risignal receiver from 802.16njthe total of signals andrjnoise,receiver from 802.11ijs , s rfori = 1, 2,.mandj = 1, 2,.ni = si + nijjj& = s + n(1)the average energy of a signal for each system is21 m221 n 2m sii =1= and s j= nj =1(2)where and respectively. are the signal wavelengths coming from wimax and wlanin order to select the better signal, we are going to find the maximum of the signals as defined below .when the mobile 802.16 and 802.11 is in coverage 802.16 and 802.11 network it receivesboth of the signalsi = 1, 2,.mfrom 1 to m and from 1 to n, where m and n arethe numberof signals coming from wimax and wlan respectivelympb = pi pr (b1k 3 (ri ) = max 1im b(ri ) / si )i =1(3)is the probability of the threebest signals selected fromm numbers of different signals coming from 802.16 and placed in order in the most upper topandnp = p p (b(r ) = maxb(r ) / s )(4)bi r j =11k 3j1 jnjjis the probability of the threebest signals selected fromn numbers of different signals coming from 802.11 and placed in order in the most upper top .after choosing the three best signal from each system is called pre-final-selection, there areonlyk i ， k = 1, 2, 3andk j, k = 1, 2, 3rk = sk + nkandk =k + k (5)snk is the number of trials of selection from the three most top signals before the decision is made.in the final selection process the balance machine compares between the two first dominant signals defined as k+1 and k+1 and choose the best one, if in the first comparison by the balance machine ifk+1 and k+1 are the same then the machine goes to the second comparison definedas k+2 and k+2 and choose the best one from either of the two.if again k+2 and k+2 are the same then e machine goes to the last comparison from either k+3 or k+3 and choose the better one.if still k+3 and k+3 are the same then the machine made decision by choosing a fortiori the first k from the wimax because of the wimax network is larger than wlan in coverage area.for the evaluation of two different signal, its important to use two markov chain for thestationary distribution with joint probability for doing the comparison by using dominant functiond(pbpb )define aspb p pb (6)p (s, sp (s , s )p (s , s ) log bk1 k1(7)d(pbpb ) =k1,k1bk1k1b k1 k1pb p pb meaningis pbdominantpb the contour with indicate 802.16and tour on1 meaning active node only on signal from 802.16 and 802.11 is 0 meaning tourney sleep node thesignal usesk1is bestone only use if again a fortiori the counter decide to choose is best one onlythe counter node is defined as (0+1=1 or 1+0=1) for the decision taking.let us assume the power of the received information signal by this mobile received802.16-802.11 is sufficient, and then the channel coherence bandwidth play the role of the measure of frequency selectivity expressed bybcoh 12rms(8)where rmsis the measure for time dispersion of the channel.when the user moves, it results into doppler effect, frequency change, however, the mobile multi signal receiver still have the ability to continue to select the right signal even on motion ,doppler frequency of wimax and wlan aredefined respectivelybyf = dandf= d (9)where is the relative velocity and and wimax and wlan respectively.are the signal wavelengths coming fromthe measure of the time selectivity during the movement of the mobile multi-signal receiver called the channels coherence time of wimax and wlan are given respectively by the inverseof the doppler frequency which is defined astcoh 1 = fdandtcoh1 =fd(10)the path loss (pl) signal attenuation depends on the distance between the base station bsandtheaccess point ap from the mobile multi-signal receiverrespectivel