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. The uplink(mobile to base station) frequency is different from downlink frequency(base station to mobile).["center" colspan = "3"|'''[Imagemailto:cdma6info@dolcera.jpgcom <span style="color:#0047AB">Buy the customized report from Dolcera</span>]''' |thumb|700px-|align = "center"|[http://www.aidolcera.u-hyogo.ac.jpcom/~thai-projwebsite_prod/presenservices/20051222ip-Ishikawa.ppt FDMA]]patent-analytics-services Patent Analytics Services]|align === Time Division Multiple Access ===In this system, each user is allocated a different time slot. Forward link frequency and reverse link frequency is the same. A synchronous switch is responsible for the time switching.[[Image:cdma10.jpg|thumb|600px|"center"|TDMA]] === Code Division Multiple Access ===There is no restriction on time and frequency in this scheme. All the users can transmit at all times and at all frequencies. Because users are isolated by code, they can share the same carrier frequency, eliminating the frequency reuse problem encountered in other technologies.[[Imagehttp:cdma11//www.jpg|thumb|600 px|centre|CDMA]]<br> A comparative study between the above three access technologies with respect to time and frequency is as shown belowdolcera.[[Image:cdma12.jpg|thumb|600 px|centre|Comparison of cellular access schemes]] == Code Division Multiple Access ==The CDMA technology can be implemented in two ways* Direct Sequence Spread Sprectrum com/website_prod/services/business- DSSS CDMA* Frequency Hopping research- FH CDMAservices Market Research Services]|align === Direct Sequence Spread Sprectrum - DSSS CDMA === In this method, the direct sequence(input data) which is spread over a limited bandwidth is multiplied with a code or spreading sequence (a pseudorandom sequence) which will spread the input data over the entire bandwidth of the communication channel. The power density is also reduced and is spread over the frequency spectrum and hence is known as spread spectrum method. The modulation part of DSSS is as shown below.[[Image:cdma13.jpg|thumb|600px|"center"|CDMA Modulation]]The modulated signal is transmitted over the channel and all users can receive it but only the user which knows the correct code can decode the message. This is depicted in the figure below.[[Imagehttp:cdma14//www.jpg|thumb|600px|center|CDMA Demodulation]dolcera.com/website_prod/tools/patent-dashboard Purchase Patent Dashboard]|-|align === 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. === Soft Handoff === Handoff means switching a cellular phone transmission from one cell to another as 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 breakcenter". In CDMA, due to this soft handoff, there is no interruption of call even at the border of a cell site which means more number of customers can be accommodated, automatically increasing the capacity of the cell site. === Multipath Fading === In a mobile environment, a mobile station will receive one direct signal from the base station and multiple signals which are reflected from obstructions like buildings and towers. Each signal would have travelled a different length and would be displaced in time. Due to this, when they are combined at the mobile handset, it will cause interference resulting in poor signal quality. This is known as ''fading''. This problem is handled in a very good way in CDMA. Here, the phase of the multiple signals is modified such that only positive interference(addition) takes place and the overall signal strength increases. A receiver that implements the above principle is known as a RAKE receiver as shown in the figure below.| [[Imagehttp:cdma15//www.jpg|thumb|center|600px|RAKE receiver]]=== Near Far Problem === The problem is best described by taking an example: Consider a receiver and two transmitters (one close to the receiver; the other far away)dolcera. 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 transmission's signal is the other's noise the signalcom/website_prod/services/ip-topatent-noise ratio (SNR) for the farther transmitter is much lower. If the nearer transmitter transmits a signal that is orders of magnitude higher than the farther transmitter, then the SNR for the farther transmitter may be below detectability and the farther transmitter may just as well not transmit. This effectively jams the communication channel. In CDMA systems, this is commonly solved by dynamic output power adjustment 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 be dramatically different depending on distance from the base station.analytics-services/patent-search/patent-landscapes Patent Landscape Services][[Image:cdma16.jpg|thumb|600px|align = "center"|Dynamic output power adjustment for CDMA transmitters]] ====Power Control==== As the propagation losses between BS and MS's are different according 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 power. Moreover, 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>.[[Imagehttp:cdma17//www.jpgdolcera.com/website_prod/research-processes Dolcera Processes]]<br>Power control can be implemented in two ways : open loop power control and closed loop power control<br>|align = "center"| [[Imagehttp:cdma18//www.jpg]dolcera.com/website_prod/industries Industry Focus] '''Effect of 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.|align = "center"| [[Imagehttp:cdma19//www.jpg]] ==Quality of Service(QoS)==CDMA is being accepted as a third generation (3G) system and a specific feature of 3G systems is that they offer a radio interface adapted for all kinds of services and combination of services (such as data, voice, video etc)dolcera. The big challenge is multiplexing these com/website_prod/services which have do not have the same demands in terms of quality of service(QoS) which can be represented as BER(bit error rate), processing delay, frame error rate etc. Different QoS will require different channel encoding and interleaving strategies. The demand of BER can be satisfied when the coding bits have at least a code dependent ratio Eb/I(ratio of bit energy to interference). There are several influences that might change system performance(BER) and hence Ebip-patent-analytics-services/patent-search/I ratio, of which the most effective is variation of Bit Rate by a step of '''Rate Matching'''.patent-landscapes Patent Search Services]|align ===Rate Matching and QoS===The patent ["center"| [http://v3www.espacenetdolcera.com/textdoc?DB=EPODOC&IDX=EP1385290&F=0 EP1385290]] titled "Method for balancing Ebwebsite_prod/I ratio in a service multiplexing CDMA system services/ip-patent-analytics-services/alerts-and a telecommunication system using this method-updates Patent Alerting Services]|align = " 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). The following framework highlights the various steps involved in providing variable QoS. The received data from the transport block is classified into different processes based on their QoS. Data is split onto various transport channels to which a CRC code is attached for error correction. Further, all these transport channels are multiplexed on one line by concatenation, interleaved, segmented and then 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 is occuring). center"| [[Imagehttp:cdma20//www.dolcera.jpg]com/website_prod/tools Dolcera Tools]|-|}<br>===Power Control, Rate Matching and QoSCode 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 computes and assigns a new spreading factor for each data rate and hence the optimal powers power calculation is done according to the new spreading factor for each radio frameas follows. <br> Spreading factor(Gi) is defined as the ratio of bandwidth of the system to the data rate of the radio frame.

This power index will ascertain the optimal power to be alloted to each service channel(each data rate for different services).<br>

Hi is path loss which is dependent on the distance and is a costant constant for a path,<br>

From the above analysis, we observe that when the bit rate mobile is inversely proportional to sent the spreading factor optimal power at which will inversely effect it should transmit. It can backtrack and calculate the power index and spreading factor and hence the optimal powerData rate is changed accordingly. Therefore, This step can be considered to be an equivalent to the Bit Rate and Optimal power go hand in hand, and have the same effect on Eb/I and QoSMatching Algorithm explained above. The method and algorithm to schedule optimal power is detailed in the IEEE paper 765366 [[Media:IEEEGurbuz.pdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]].

===Power control and QoSDynamic Resource Scheduling(DRS) Algorithm===Transmission power The Mobile Station(MS) performs Matching of mobile station is proportional Traffic Descriptors such as Peak Cell Rate(PRC),Sustainable Cell Rate(SCR) and obtains the connection parameters like average cell rate, SIR, Delay from them. These parameters are sent to power control lawthe Base Station(BS) where they are queued in a FIFO. The BS determines a spreading factor which allocates the Orthogonal Varible Spread code(OVSF) using '''Gi = W / Ri''', where W=system bandwidth which is a function constant for a system and Ri= data rate of distance from the radio frame.<br> The base stationcalculates a value of power index '''gi= (vi / (vi+Gi))'''and hence Power levels using '''Pi = (gi*No*W )/ (Hi*(1-(Sgj))''', transmission rateswhere S stands for sumof, interference level and transmits them to the MS. This information is conveyed to the MS using TPC(number of active usersTransmission Power Control). In this bits and a closed loop power control method as explained in section 5.6 above is performed to obtain the Bit Error probability final value of the multi rate CDMA mobile station is calculated power at which transmission should be done.The method and algorithm to schedule optimal power using Dynamic Resource Scheduling is detailed in the IEEE paper 765366 [[Media:IEEEGurbuz.pdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]]. ===Optimal Power Control Algorithm===The Base Station receives a Pilot Signal from the Mobile station using transmission rates and calculates BER based on Distance,Transmission rate and No of Users in the mobileCell.The Optimal Ptk is the transmitted signal power which is expressed by the power control functions are derived based on function g ( rt , k ), a function of the Bit error probability at distance from the mobile tobase station and these ,'''Ptk= g(rt,k)Po''' where Po is the maximum transmission power. The optimum power control functions are transmitted to the mobile. The mobile Mobile station which calculates the optimum optimal power using DYNAMIC PROGRAMMING and transmits its data starts transmitting at this power levelthat value. It Thus meeting the required QoS parameters.The method and algorithm for optimal power control is of interest to note that detailed in the optimum IEEE paper 503476 [[Media:IEEEYao.pdf|Optimal power level control law for Multi-media - Multi-rate CDMA systems- Shee Yao and Evaggelos Geraniotis]]. ==Research Activity (Non Patent) in the Period (1991-2003)==NOTE: The analysis presented below is related with respect to power index the IEEE Papers published between 1991-2003 which will determine focus on the spreading gain aspect of Quality of Service and hence its Management using various paramters like Rate matching, Power control, Variable Spreading Factor etc. [[Image:Publication_Year.JPG|center|thumb|500 px|Number of publications VS Year of publication]]The above analysis suggests a increase in the overall bit rateResearch activity in the area of QoS Management in the year 1999. Thus  [[Image:Publishers.JPG|center|thumb|500 px|Publisher VS number of publications during(1991-2003)]] It is to be noted that the optimum power level non patent research is acheived by transmitting attributed mostly to universities in USA and Asia Pacific. The mention of '''IEEE member''' in the data at above graph indicates the calculated bit rateabsence of information about the parent department of the Researcher. [[MediaImage:IEEECDMA_-2_3D.pdfJPG|center|thumb|500 px|Graph showing number of publications by 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|}