Changes

== Cellular Communication communication==A cellular mobile communications system uses a large number of low-power wireless transmitters to create cells — the basic geographic service area of a wireless communications system. Variable power levels allow cells to be sized according to the subscriber density and demand within a particular region. As mobile users travel from cell to cell, their conversations are handed off between cells to maintain seamless service. Channels (frequencies) used in one cell can be reused in another cell some distance away. Cells can be added to accommodate growth, creating new cells in unserved areas or overlaying cells in existing areas. [http://www.IEC.org Source[CDMA Basics]]

There are three main entities in cellular communication* Mobile Station (MS): A mobile station consists of 2 entities - equipment In the next sections we discuss the basics for the Patents EP1385290 and SIM cardEP1156616.* Base Transceiver station ==Quality of Service(BTSQoS): A base transceiver station consists of 2 entities - ==CDMA is being accepted as a base transceiver third generation (transmitter and receiver3G) station system and a base station controller. The BTS specific feature of 3G systems is the antenna tower site.* Main Switching centrethat they offer a radio interface adapted for all kinds of services and combination of services (MSCsuch as data, voice, video etc): . The main switching centre big challenge is multiplexing these services which do not have the heart same demands in terms of the network - the central switching office quality of service(QoS) which controls all the base stations and provides connection with landline phones. It performs three main tasks. It:# connects calls from sender to receivercan be represented as BER(bit error rate),# collects details of the calls made and receivedprocessing delay, frame error rate etc. Different QoS will require different channel encoding and# supervises operation interleaving strategies. The demand of BER can be satisfied when the rest coding bits have at least a code dependent ratio Eb/I(ratio of the network componentsbit energy to interference).

== Cellular System Architecture =Need for Rate Matching===Cellular systems are increasing In a system using Multiple Access CDMA technology, the greater the Eb/I ratio the greater is the QoS. Transport channels having different QoS requirement do not have the same need in demand as more users are added to their systemsterms of Eb/I ratio. The amount If all the channels are allocated a fixed Eb/I ratio which corresponds with the maximum required by a transport channel then other channels will have "too" good a Quality of frequency spectrum available for mobile cellular use was limitedService, needlessly causing '''interference and efficient use of resource blocking'''. There are several influences that might change system performance(BER) and hence Eb/I ratio,in accordance with the required frequencies was needed QoS of which the most effective is variation of Bit Rate by a step of '''Rate Matching'''. The standard framework for mobile cellular coveragethe management of QoS in CDMA systems is shown below. In modern cellular telephony, rural and urban regions are divided The following framework highlights the various steps involved in providing variable QoS. The received data from the transport block is classified into areas according to specific provisioning guidelinesdifferent processes based on their QoS. Provisioning for each region Data is planned according split onto various transport channels to an engineering plan that includes cellswhich a CRC code is attached for error correction. Further, clustersall these transport channels are multiplexed on one line by concatenation, frequency reuseinterleaved, segmented and handoversthen rate matched.The rate matching step is performed using the rate matching ratio and puncturing ratio which is received from the sending entity (an exchange of handshaking signals occurs).<br>[[Image:cdma_2_7.jpg|thumb|700px|center|QoS Management in CDMA - Standard Framework]]

==== Cells ==== A cell The rate matching step in above figure is the basic geographic unit of essentially implemented by repetition or puncturing, SIEMENS has proposed an algorithm to ETSI, to obtain a cellular systemnon-integer punture/repetition ratio referenced SM/G2/UMTS-L1/Tdoc428/98 and it is given as follows. Cells are base stations transmitting over small geographic areas that are represented This algorithm is used as hexagonsa standard approach for Rate Matching. [[Image:cdma21.jpg|thumb|700px|center|Rate matching algorithm by SEIMENS]]

==== Clusters ==== A cluster is a group of cells. No channels are reused within a cluster. Normally a cluster has seven cells in it as shown below[[Image:Cdma1.JPG|thumb|center|700 px|CDMA Basics]]

==== Frequency Reuse ====The number of radio channel frequencies is limited. The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area. Cells are assigned a group of channels that is completely different from neighboring cells. The coverage area of cells is called the footprint. This footprint is limited by a boundary so that the same group of channels can be used in different cells that are far enough away from each other so that their frequencies do not interfere[[Media:Cdma_talk.pdf|CDMA basics]]

==== Cell Splitting =QoS Management Algorithms=== As a service area becomes full Quality of users, this approach is used to split a single area into smaller ones. In this way, urban centers Service can be split into as many areas as necessary managed according to provide acceptable service levels in heavy-the varying type of traffic regionsi.e. data, while largervoice, less expensive cells can be used to cover remote rural regionsvideo in the following four ways.# Rate Matching Algorithm# Code Hopping Algorithm# Dynamic Resource Scheduling(DRS) Algorithm# Optimal Power Control Algorithm[[Image:cdma_22.jpg|thumb|600 px|center|QoS Management in CDMA - Analysis restricted till 1999]]

===Rate Matching Algorithm= Handoff ==The patent [http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=EP1385290&F=0 EP1385290] titled "Method for balancing Eb/I ratio in a service multiplexing CDMA system and a telecommunication system using this method" targets this concept of Rate matching and introduces an algorithm for calculating effective data output bits by a process of repetition or puncturing of the input bits governed by a '''rate matching ratio''' and '''puncturing ratio''' received from the sending entity (can be a BS or MS). As the number of services increases the number of potential combinations will also increase. There arises a need for simple arithmetic procedures to calculate the transport sizes which is done using the following three rules.# The first rule concerns Channel encoding wherin the transport block is converted into the coded block by a possible relation of the form Y=X/(coding rate)+Ntail# The second rule concerns segmentation of the coded block into the size of the segment produced by segmentation per multiplexing frame# The third rule is about obtaining the size of the oputput block Y from the Input block X according to a rate matching step explained below.<br>The Parameters Ei(Energy per bit),Pi(Max puncture Rate) and Xi(Input data rate) are the characteristic constants of a transport channel both at the Mobile Station(MS) and the Base Station(BS). Initially Ei,Pi and Xi are determined at the Base Station and a maximum possible payload is calculated. This is known as the intermediate size and and a vector of expected is transmitted to the Mobile Station(MS) along with the parameters Ei and Pi. Using the values of Pi,Ei and Xi the mobile will also calculate its output frame size Yi. Then final step is matching this value of Yi with the received vector of Intermediate values Yi and decide the final frame size. The bits are repeated or punctured according to the required Final Frame Size.<br>

==Evolution of Cellular Systems=<span style=[[Image"color:cdma1.jpg|500 px|center]]#C41E3A">Like this report?</span>== Multiple Access Methods =<p align="center"> '''This is only a sample report with brief analysis''' <br>There are predominantly three types of multiple access methods.'''Dolcera can provide a comprehensive report customized to your needs'''</p>{|border="2" cellspacing="0" cellpadding= Frequency Division Multiple Access "4" align="center" "|style="background:lightgrey" align =In this system, each user is allotted a different set of frequencies to operate upon"center" colspan = "3"|'''[mailto:info@dolcera. The uplink(mobile to base station) frequency is different com <span style="color:#0047AB">Buy the customized report from downlink frequency(base station to mobile)Dolcera</span>]''' |-| align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services Patent Analytics Services]|align = "center"| [http://www.dolcera.com/website_prod/services/business-research-services Market Research Services]|align = "center"| [Imagehttp:cdma6//www.jpgdolcera.com/website_prod/tools/patent-dashboard Purchase Patent Dashboard]|thumb-|700pxalign = "center"|[http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/patent-search/patent-landscapes Patent Landscape Services]|align = "center"|[http://www.aidolcera.ucom/website_prod/research-hyogoprocesses Dolcera Processes]|align = "center"| [http://www.acdolcera.jpcom/~thaiwebsite_prod/industries Industry Focus]|-proj|align = "center"| [http:/presen/20051222www.dolcera.com/website_prod/services/ip-Ishikawapatent-analytics-services/patent-search/patent-landscapes Patent Search Services]|align = "center"| [http://www.ppt CDMA]dolcera.com/website_prod/services/ip-patent-analytics-services/alerts-and-updates Patent Alerting Services]|align = "center"| [http://www.dolcera.com/website_prod/tools Dolcera Tools]|-|}<br>===Code Hopping Algorithm===According to one of the methods of dynamic power control (Code Hopping) used in W-CDMA technology, the Rate Information (RI) field in the uplink control channel in W-CDMA frame can be used to notify the base station about the variable bit rates (VBR) it wants to send, then the base station assigns a new spreading factor for each data rate and hence the optimal power calculation is done according to the spreading factor as follows.<br> Spreading factor(Gi) is defined as the ratio of bandwidth of the system to the data rate of the radio frame.Mathematically,<br>'''Time Division Multiple Access:Gi = W / Ri'''In this ,where W=system each user bandwidth which is allocated a different time slot.Forward link frequency constant for a system and reverse link frequency is the sameRi= data rate of radio frame. <br>A synchronous switch power index (gi) is responsible to do calculated from this Spreading Factor(Gi) using the time switching.[[Image:cdma10.jpg]]following expression<br>'''Code Division Multiple Access:gi= (vi / (vi+Gi))'''There , where vi is no restriction on time and frequency in this scheme. All minimum QoS for the users can transmit at all times and at all frequenciesith session which is a constant. Because users are isolated by code, they can share <br> This power index will ascertain the same carrier frequency, eliminating the frequency reuse problem encountered in other technologiesoptimal power to be alloted to each service channel(each data rate for different services).<br>[[Image:cdma11.jpg|600 px|centre]]'''Pi = (gi*No*W )/ (Hi*(1-(Sgj)'''<br>A comparative study between where No is AWGN(Additive White Guassian Noise)a constant,<br> Hi is path loss which is dependent on the above three access technologies with respect to time distance and frequency is as shown belowa constant for a path,<br>.[[Image:cdma12and Sgj is sum of the power index of all the sessions which is constant for all sessions of the radio frame.jpg|600 px|centre]]

==Code Division Multiple Access==The CDMA technology can be implemented in two ways* Direct Sequence Spread Sprectrum - DSSS CDMA* Frequency Hopping - FH CDMA'''Direct Sequence Spread Sprectrum - DSSS CDMA:''' In this method From the direct sequence(input data) which above analysis, we observe that when the mobile is spread over a limited bandwidth is multiplied with a code or spreading sequence (a pseudorandom sequence) sent the optimal power at which will spread the input data over the entire bandwidth of the communication channelit should transmit. The power density is also reduced It can backtrack and is spread over calculate the frequency spectrum power index and spreading factor and hence the Data rate is known as spread spectrum methodchanged accordingly. The modulation part of DSSS is as shown below<br>[[Image:cdma13This step can be considered to be an equivalent to the Rate Matching Algorithm explained above.jpg]]The modulated signal is transmitted over the channel method and all users can receive it but only the user which knows the correct code can only decode the message. This algorithm to schedule optimal power is depicted detailed in the figure below.<br>IEEE paper 765366 [[ImageMedia:cdma14IEEEGurbuz.jpgpdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]]===Features of CDMA=======Frequency Reuse==== Number of radio channel frequencies are limited. The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area. Cells are assigned a group of channels that is completely different from neighboring cells. The coverage area of cells is called the footprint. This footprint is limited by a boundary so that the same group of channels can be used in different cells that are far enough away from each other so that their frequencies do not interfere.

====Soft Handoff==== Handoff means Switching a cellular phone transmission from one cell Thus, we conclude that by adjusting the optimal power we are actually trying to another as implement a mobile user moves into a new cellular area. It is so called because the radio link with the previous sector(s) is not broken before a link is established with a new sector; this type of handoff is described as "make before break". In CDMA due to this soft handoff there is no interruption of call even at the border of cell site which means more number of customers can be accommodated automatically increasing the capacity of the cell siterate matching step.

===Dynamic Resource Scheduling(DRS) Algorithm=Multipath Fading==== In a mobile environment a mobile station will receive one direct signal from The Mobile Station(MS) performs Matching of Traffic Descriptors such as Peak Cell Rate(PRC),Sustainable Cell Rate(SCR) and obtains the base station and multiple signals which are reflected connection parameters like average cell rate, SIR, Delay from obstructions like building and towersthem. Each signal would have travelled a different length and would be displaced in time. Due These parameters are sent to this when the Base Station(BS) where they are combined at the mobile it will cause interference resulting queued in poor signal qualitya FIFO. This is called as fading. This problem is handled in The BS determines a very good way in CDMA. Here spreading factor which allocates the phase of the multiple signals is modified such the only positive interferenceOrthogonal Varible Spread code(additionOVSF) takes place the overall signal strength increases. A receiver that implements the above principle using '''Gi = W / Ri''',where W=system bandwidth which is known as a RAKE receiver as shown in the figure belowconstant for a system and Ri= data rate of radio frame.<br>[[Image:cdma15.jpg]]====Near Far Problem==== The problem is described by taking an example consider base station calculates a receiver and two transmitters value of power index '''gi= (one close to the receiver; the other far awayvi / (vi+Gi)). If both transmitters transmit simultaneously '''and at equal powers, then due to the inverse square law the receiver will receive more power from the nearer transmitter. This makes the farther transmitter voice more difficult to understand. Since one transmissionhence Power levels using 's signal is the other's noise the signal'Pi = (gi*No*W )/ (Hi*(1-to-noise ratio (SNRSgj)) ''', where S stands for sumof, and transmits them to the farther transmitter is much lowerMS. If the nearer transmitter transmits a signal that This information is orders of magnitude higher than the farther transmitter then conveyed to the SNR for the farther transmitter may be below detectability MS using TPC(Transmission Power Control) bits and the farther transmitter may just a closed loop power control method as well not transmitexplained in section 5. This effectively jams 6 above is performed to obtain the communication channel. In CDMA systems this is commonly solved by dynamic output power adjustment final value of the transmitters. That is the closer transmitters use less power so that the SNR for all transmitters at the receiver is roughly the same. This sometimes can have a noticeable impact on battery life, which can transmission should be dramatically different depending on distance from the base stationdone.<br>[[Image:cdma16.jpg]]====Power Control:==== As the propagation losses between BS The method and MS's are different according algorithm to individual communication distances, the received levels at the base station are different from each other when all mobile stations transmit their signals at the same schedule optimal power. Moreover, using Dynamic Resource Scheduling is detailed in the received level fluctuates quickly due to fading. In order to maintain the strength of received signal level at BS, power control technique must be employed in CDMA systems.<br>.IEEE paper 765366 [[ImageMedia:cdma17IEEEGurbuz.jpgpdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]]<br>Power control can be implemented in two ways : open loop power control and closed loop power control<br>[[Image:cdma18.jpg]]

'''Effect of ===Optimal Power Control''' Power control is capable of compensating the fading fluctuation. Received power from all MS are controlled to be equal.　Near-Far problem is mitigated by the power control.[[Image:cdma19.jpg]]Algorithm==Quality of Service(QoS)==CDMA is being accepted as The Base Station receives a third generation system Pilot Signal from the Mobile station and a specific feature of 3G system is that it offers a radio interface adapted for all kinds of services calculates BER based on Distance,Transmission rate and combination No of services(data,voice,image etc)Users in the Cell. The big issue Ptk is of multiplexing of these services the transmitted signal power which have do not have is expressed by the same demands in terms of quality of servicepower control function g (QoS) which can be represented as BER(bit error ratert , k ),processing delay,frame error rate etc. Different QoS will require different channel encoding and interleaving strategies. The demand a function of BER can be satisfied when the coding bits have atleast a code dependent ratio Eb/I(ratio of bit energy distance from the mobile to interference). There are several influences that might change system performance(BER) and hence Eb/I ratiobase station, of which the most effective is variation of Bit Rate by a step of '''Rate MatchingPtk= g(rt,k)Po'''where Po is the maximum transmission power. <br><br>===Rate Matching The optimum power functions are transmitted to the Mobile station which calculates the optimal power and starts transmitting at that value. Thus meeting the required QoS===parameters.The patent '''EP 1385290 titled Method for balancing Eb/I ratio in a service multiplexing CDMA system and a telecommunication system using this method''' targets at this concept of Rate matching and introduces an algorithm of calculating effective data output bits by a process of repetition or puncturing of for optimal power control is detailed in the input bits governed by a '''IEEE paper 503476 [[Media:IEEEYao.pdf|Optimal power control law for Multi-media - Multi-rate matching ratio''' CDMA systems- Shee Yao and '''puncturing ratio''' received from the sending entity(can be BS or MS). The following framework highlights the various steps involved in providing variable QoSEvaggelos Geraniotis]].

===Power Control, Rate Matching and QoS===According to one of the methods of dynamic power control Research Activity (Code HoppingNon Patent) used in W-CDMA technology, the Rate Information Period (RI) field in the uplink control channel in W1991-CDMA frame can be used to notify the base station about the variable bit rates (VBR2003) it wants to send, then the base station computes and assigns optimal powers according to the new spreading factor for each radio frame. Spreading factor(Gi) is defined as the ratio of bandwidth of the system to the data rate of the radio frame.Mathematically,<br>'''Gi = W / Ri''',where W=system bandwidth which is a constant for a system and Ri= data rate of radio frame.<br>A power index (gi) NOTE: The analysis presented below is calculated from this Spreading Factor(Gi) using with respect to the following expression<br>'''gi= (gi / (gi+Gi))''', where gi is minimum QoS for the ith session which is a constant.<br> This power index will ascertain the optimal power to be alloted to each service channel.<br> '''Pi = (gi*No*W )/ (Hi*(1IEEE Papers published between 1991-(Sgj)'''<br>where No is AWGN(Additive White Guassian Noise)a constant,<br> Hi is path loss 2003 which is dependent focus on the distance and is a costant for a path,<br> and Sgj is sum aspect of the power index Quality of all the sessions which is constant for all sessions of the radio frame. <br>From the above analysis, we observe that Bit Service and its Management using various paramters like Rate is inversely proportional to Spreading factor which will inversely effect the power index and hence the optimal power. Thereforematching, Power control, the Bit Rate and Optimal power go hand in glove and have the same effect on Eb/I and QoS.The method and algorithm to schedule optimal power is detailed in the IEEE paper '''Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA Ozgur Gurbuz, Henry Owen'''. Thus we conclude that by adjusting the optimal power we are actually trying to implement a rate matching step.[[Media:ieee1Spreading Factor etc.pdf]]

===Power control and QoS===SPEECH transmission is the main service supported by the first two generations of mobile communication systems[[Image:Publication_Year. However, future systems should be able to handle a wide variety JPG|center|thumb|500 px|Number of different services with bit rate requirement ranging from a few kilobits/s to as much as 2 Mb/s. There are many ways to design a CDMA system to support multirate services . One way to do so is to spread all signals, independent publications VS Year of the bit rate, to the same bandwidth . This is done by keeping the chip rate constant. Users transmitting at low bit rate thus have publication]]The above analysis suggests a high processing gain. This allows those users to transmit at a lower power. Therefore, increase in the conventional constant received power scheme is not appropriate Research activity in such a multirate system. A more sophisticated power control scheme is needed to achieve diverse quality the area of service (QoS) and rate requirement. One such scheme which explores the relationship between the data rate, the QoS, and the transmit power is presented Management in the IEEE paper '''Power Control and Rate Management for Wireless Multimedia CDMA Systems Chi Wan Sung, Member, IEEE, and Wing Shing Wong, Senior Member, IEEEyear 1999.'''===Dynamic Resource Scheduling and QoS===Dynamic Resource Scheduling [[Image:Publishers.JPG|center|thumb|500 px|Publisher VS number of publications during(DRS1991-2003) has been proposed as an adaptive resource management and QoS]]provisioning framework applicable It is to W-CDMA systems. Various spreading strategies like Fixed Spreading Gain (FSG), Variable Spreading Gain (VSG) and Multi Code (MC) strategies and their performance be noted that the non patent research is compared attributed mostly to universities in terms USA and Asia Pacific. The mention of power saving, resource allocation and QoS stability in the IEEE paper '''DYNAMIC RESOURCE SCHEDULING STRATEGIES FOR QOS IN W-CDMA by Ozgur Gurbuz, Henry Owen.IEEE member''' VSG-DRS and MC-DRS outperform in the FSGabove graph indicates the absence of information about the parent department of the Researcher. [[Image:CDMA_-DRS for capacity as a result _3D.JPG|center|thumb|500 px|Graph showing number of the statistical multiplexing gain created publications by adaptive bandwidth usage.the publishers during 1991-2003]]

Substantial amount of research has been done in the field of QoS in CDMA communication system in the year 1998-99 and this has led to the invention of multitude of methodologies ranging from power control to Rate matching and so on Dynamic Resource scheduling, all with the sole aim of improving QoS. ==<span style="color:#C41E3A">Like this report?</span>==<p align="center"> '''This is only a sample report with brief analysis''' <br>'''Dolcera can provide a comprehensive report customized to your needs'''</p>{|border="2" cellspacing="0" cellpadding="4" align="center" "|style="background:lightgrey" align = "center" colspan = "3"|'''[mailto:info@dolcera.com <span style="color:#0047AB">Buy the customized report from Dolcera</span>]''' |-| align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services Patent Analytics Services]|align = "center"| [http://www.dolcera.com/website_prod/services/business-research-services Market Research Services]|align = "center"| [http://www.dolcera.com/website_prod/tools/patent-dashboard Purchase Patent Dashboard]|-|align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/patent-search/patent-landscapes Patent Landscape Services]|align = "center"| [http://www.dolcera.com/website_prod/research-processes Dolcera Processes]|align = "center"| [http://www.dolcera.com/website_prod/industries Industry Focus]|-|align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/patent-search/patent-landscapes Patent Search Services]|align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/alerts-and-updates Patent Alerting Services]|align = "center"| [http://www.dolcera.com/website_prod/tools Dolcera Tools]|-|}<br>==Contact Dolcera== {| style="border:1px solid #AAA; background:#E9E9E9" align="center"|-! style="background:lightgrey" | Samir Raiyani|-| '''Email''': [mailto:info@dolcera.com info@dolcera.com]|-| '''Phone''': +1-650-269-7952|}