CN104660298A - Novel method and device for mapping pilot signals in unicast and broadcast multicast multiplexed mode - Google Patents
Novel method and device for mapping pilot signals in unicast and broadcast multicast multiplexed mode Download PDFInfo
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Abstract
The invention discloses a novel method and device for mapping pilot signals in a unicast and broadcast multicast multiplexed mode. In TD-SCDMA, the pilot pollution is defined mainly through the study of PCCPCH; definitions of a strong pilot and a strong enough main pilot are introduced to the pilot pollution of TD-SCDMA; in CDMA, when an active set of a mobile station contains four or more pilot signals, wherein the difference between Ec/Io values of each of the pilots and the best pilot is less than 6dB, the differences are all greater than a T_ADD threshold, and none of these pilot signals is strong enough to be a real main pilot; in these areas, the sudden appearance of other strong pilot signals beyond the active set results in a call-drop phenomenon in the switching process, the strong pilot signals become potential interference sources, so as to derive the pilot pollution.
Description
The method and apparatus of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention belongs to signal of telecommunication application.
Pilot signal makes subscriber station can obtain the forward direction CDMA channel time limit, provides coherent demodulation phase reference, and provides signal strength signal intensity to compare means nationality to determine when to switch for each base station.
CDMA technology, Chinese commercialization 3 years, obtains development at full speed.
The user of current Chinese cdma network breaches 2300 general-purpose families, becomes second-biggest-in-the-world CDMA net.
Along with the expansion of network size and the continuous increase of user, cdma network construction by to expand area coverage for target, transfer to Strengthens network optimization, improve on signal quality.
In some urban areas, the capacity of a carrier frequency is inadequate gradually, starts to increase new carrier frequency.Between adjacent community, the unbalanced phenomenon of carrier frequency quantity gets more and more, and the problem switched between different frequencies starts to appear.
The effect in reduction cutting off rate of the soft hand-off of CDMA is obvious, but its switching competence exertion effect only between same carrier.
For the switching between different carrier frequency, direct-cut operation can only be adopted to realize.
The success rate of direct-cut operation is relatively low, and the direct-cut operation especially between the different carrier frequency of different base station, is easy to cause call drop.
Clean culture: the communication between network node just looks like be that dialogue between people is the same.
If a people speaks to another one people, so describing with the term of network technology is exactly " clean culture ", and the now reception and transmitting of information is only carried out between the two nodes.
Clean culture is widely used in a network, and on network, the data of the overwhelming majority are all transmit with the form of clean culture, and just general networking user does not know.You sending and receiving e-mail, browsing page time, must connect with mail server, Web server, what now use is exactly unicast data transmission mode.
But usually use " point-to-point communication " (Point to Point) to replace " clean culture " because " clean culture " generally with " multicast " and " broadcast " corresponding use.
Multicast: " multicast " also can be called " multicast ", be not a lot of in the application of network technology, online video meeting, online video program request are particularly suitable for adopting multicast.
Because if employing mode of unicast, one by one node-node transmission, have how many destination nodes, just have how many times transport process, the obvious efficiency of this mode is extremely low, is worthless; If adopt the broadcast mode do not distinguished target, all send, although once can data have been transmitted, obviously do not reach and distinguished the object that particular data receives object.
Adopt multicast, both can realize the data once transmitting all destination nodes, also can reach the object only special object being transmitted to data.
The multicast of IP network is generally realized by Multicast IP Address.
Multicast IP Address is exactly Class D IP address, the IP address namely between 224.0.0.0 to 239.255.255.255.
The automatic distribution of Multicast IP Address supported by DHCP manager in Windows 2000.
Broadcast: " broadcast " application is in a network more, the process automatically being obtained IP address as client computer by DHCP is realized by broadcasting.
But compare with multicast with clean culture, broadcast almost occupies all bandwidth of network in subnet.
Hub is impossible filter broadcast storm because its operation principle determines, general switch does not have this function yet, the network switch (the QS series of switch as omnidirectional) but had now also has filter broadcast storm function, and router inherently has the effect of isolation broadcast storm.
Broadcast storm can not be stopped completely, but can only propagate in same subnet, the sound just looking like loudspeaker can only be propagated the same in same meeting-place, therefore by the hundreds of platform big-and-middle-sized local area network (LAN) that even thousands of computers are formed, generally carry out sub-network division, just as a hall wall being isolated into many little Rooms, to reach the object of isolation broadcast storm.
In an ip network, broadcast address represents with IP address " 255.255.255.255 ", and this IP address represents IP addresses all in same subnet.
Pilot signal S&T capability defines, Chinese: pilot signal English name: pilot signal define: be the object measured or monitor and the signal that sends in telecommunications network.
This signal is generally single-frequency.Application branch of learning: communication science and technology (first level discipline); Principle of Communication and basic fundamental (secondary subject)
For measuring or the object of monitoring and the signal that sends in telecommunications network.This signal is generally single-frequency.
Pilot signal selects the scheduling algorithms such as gravity treatment, open Loop Power control, pilot pollution for: soft handover, community in WCDMA system, and it is corresponding without corresponding logic, transmission channel, is present in physical channel; CPICH is divided into two classes, PCPICH primary pilot channel, and each community only has 1 PCPICH, and for level detecting, channel estimating, launches in whole community; Another kind of is SCPICHD, secondary pilot channel, and there are some this channels each community, need not launch in whole community; Pilot signal is used for the phase reference of down channel.
In TFT, pilot channel power is constant is 29dBm, community threshold value: Ec>=-115dBm, Ec/I0>-20dB.
Pilot channel S&T capability definition Chinese: pilot channel English name: pilot channel defines: for the channel of the unmodulated CF signal of base station sequential filming.
Pilot channel Pilot Channel communications term, the unmodulated Direct Sequence Spread Spectrum Signal of each CDMA base sequential filming.
Pilot channel makes subscriber station can obtain the forward direction CDMA channel time limit, provides coherent demodulation phase reference, and provides signal strength signal intensity to compare means nationality to determine when to switch for each base station.
Content: all-zero code, form: pilot channel is divided into the frame of 26.67ms
Feature firm power, continues to launch, higher than the level of Traffic Channel by 4 to 6dB (being convenient to travelling carriage find), effect:
1. help mobile phone capture systems
2. Multipath searching
3. provide phase reference, help RAKE receiver to carry out Delay Estima-tion, do coherent demodulation
4. when switching, mobile phone for measuring pilot channel, carries out pilot frequency intensity and compares pilot channel Pilot Channel.
Pilot channel provides mark for travelling carriage, regularly, and phase reference (for coherent detection), and for signal strength signal intensity that power controls.
Pilot channel is the peak signal that community sends, and usually uses WC0.
Travelling carriage has the time acquisition pilot channel of 15 seconds.Pilot channel, not containing message, only contains the time shift short PN code for cell identification.
Pilot signal is the Direct Sequence Spread Spectrum Signal of base station sequential filming non-modulated, it makes mobile phone can obtain the forward direction CDMA channel time limit, there is provided correlation demodulation phase reference, and provide signal strength signal intensity to compare for each base station, mobile phone can determine when to switch.
When not having the situation of pilot beacon equipment, mobile phone roaming, under A base station, uses carrier frequency FA2 communication, and when mobile phone is gradually away from A base station, near B base station, B base station but only has carrier frequency FA1 to provide service.
The signal of the A base station FA2 that mobile phone receives is more and more weak, and B base station FA1 signal strengthens gradually, and the mode of direct-cut operation can only be adopted to switch, and can produce the interruption of 30 milliseconds.The success rate of the alien frequencies direct-cut operation of different base station is very low, is very easy to the phenomenon forming call drop.
If we have installed pilot beacon equipment in B base station, when mobile phone is under carrier frequency FA2 service, during from A base station movement to B base station, the pilot signal strength of base station near mobile phone can constantly detect.When T_Add parameter exceedes threshold value, mobile phone initiatively can send PSMM (power level measurement) message to A base station.
After A base station receives message, the configuration information of inquiry adjacent base station, finds that the pilot signal of the FA2 of B base station is actually dummy pilot signal, do not possess the possibility providing Traffic Channel, but the FA1 of B base station can provide service channel.
A base station sends EHDM (enhancement mode switches directed) message to mobile phone, and notice mobile phone is switched to carrier frequency FA1, handoff parameter is sent to mobile phone simultaneously.
Under mobile phone is first switched to the carrier frequency FA1 of A base station at once, be then switched to the carrier frequency FA1 of B base station from the carrier frequency FA1 of A base station according to the mode of soft handover, thus the switching ensured is carried out smoothly.
Pilot beacon technology due to effectively reducing cutting off rate, acting on clearly, being thus widely used after being proposed by CDMA technology standard owner Qualcomm.
According to the difference of occupation mode, following three classes roughly can be divided into:
Pilot beacon handoff functionality is just considered when design in base station.
When digital base band processor, from normal carrier frequency channel, extract pilot signal, for the transmitting of pilot beacon.
Can ensure that dummy pilot signal only includes pilot signal like this, and keep highly consistent with normal carrier frequency pilot signal.
This mode is obviously best implementation.But regrettably, the base station of many producers is not supported.
Especially microcell base station is representative, and in order to reduce cost, producer often saves the function of pilot beacon.Also be that two kinds of modes leave the market space below.
Two, pure pilot approach
Pure pilot approach adopts special channel generator to simulate pure pilot signal.Owing to only launching pure pilot tone, to the interference reduction on the carrier frequency at pilot beacon place.
But because pilot signal needs oneself to produce, the modem chip of some costlinesses be used, and internal structure more complicated.
Three, frequency shift mode
Frequency shift mode implements relatively simple, specifically from base station radio-frequency signal, all signals (comprising synchronous, paging and traffic channel signal) is all coupled to new carrier frequency and launches.
Pilot beacon equipment not only transmitting pilot signal, but also synchronizing signal, paging signal and traffic channel signal will be launched, similar to the coverage of base station for ensureing the coverage of pilot beacon like this, the power of required transmitting keeps synchronous by with the transmitting power of base station.
(1) the method and apparatus composition of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention and composition
Can effectively improve the success rate switched between different carrier frequency, extensive use in the network optimization, relatively more conventional is pilot beacon, and implementation has base station from presentation mode; Pure pilot approach; Easy frequency mode.
Pilot channel makes subscriber station can obtain the forward direction CDMA channel time limit, provides coherent demodulation phase reference, and provides signal strength signal intensity to compare means nationality to determine when to switch for each base station.
It is a part for descending power, with other down channel shared in common descending powers. the power due to transmitter is specified, therefore, the ratio that pilot power accounts for is large, will reduce the power of other down channel. and the traffic carrying capacity that they are supported will influencedly reduce.
The larger benefit of pilot power is that overlay area will be large; Smaller benefit is, the professional ability of support is large.
Pilot tone is only present in descending, main effect:
1, phase reference during UE Received signal strength;
2, accessory terminal carries out channel estimating to dedicated channel;
3, terminal carries out switching or community selection gravity treatment according to the pilot level received.
Pilot bits is present in the DPCCH of up-downgoing, effect:
1, pilot bits is one group of bit numeral provided (frame synchronization), may be used for determination and the maintenance of frame synchronization, and coherent demodulation;
2, the effect of channel estimating is also had.
Pilot pollution refers to that the intensity receiving 4 or more Ec/Io when mobile phone is all greater than the pilot tone of T_add, and wherein the intensity of neither one pilot tone greatly to occurring when can be used as dominant pilot.
Pilot pollution Ec/Io in pilot pollution district signal that is very poor and mobile phone Idle does not stop conversion to be caused mobile phone to rise to exhale difficulty; If now mobile phone is in talking state, due to the unexpected grow of certain pilot tone, it is not in the active set of travelling carriage, and at this moment mobile phone will call drop.
In TD-SCDMA, the effect of PCCPCH is substantially identical with the effect of the pilot tone in CDMA with WCDMA.
Mainly by define its pilot pollution to the research of PCCPCH in TD-SCDMA.The definition of strong pilot tone and enough strong dominant pilot is introduced in the pilot pollution of TD-SCDMA.
Namely, when certain a bit exists the too much strong pilot tone dominant pilot that but neither one is enough strong, namely pilot pollution is defined as.
In CDMA, when having four or more pilot signals in the Active Set of travelling carriage, (difference of the Ec/Io value of these pilot tones and optimal pilot is less than 6dB, and it is all large than T_ADD thresholding, and this wherein neither one signal can by force to being enough to become real dominant pilot), in these regions, other strong waveguide frequency signal not in travelling carriage Active Set there is suddenly the generation causing travelling carriage call drop phenomenon in handoff procedure, strong waveguide frequency signal becomes potential interference source, the origin of pilot pollution concept that Here it is.
One is thought, the signal branch number that existence receives is more than the quantity of Rake receiver, and these signals have exceeded given thresholding, these signals will cause serious interference to useful signal, Here it is pilot pollution, namely exceedes the number of the pilot tone number > Rake receiver of given thresholding.This given thresholding is generally taken as the settings of Tadd.
At present because an effectively point number for mobile phone is generally 3, therefore, if there is the strong component more than Tadd of more than 4, be then considered as there is pilot pollution.
One is thought, network signal level is fine, but Ec/Io is poor, and namely in a certain region, neither one has the prevailing pilot tone of sufficient intensity, and several covering pilot frequency intensity is suitable.
Rapid fading due to signal frequently switches when causing travelling carriage to converse between the Traffic Channel of different sector, very easily causes call drop.
If at this moment do not have the factor of external interference, illustrate that there is the signal from a lot of communities this area, thus cause very poor Ec/Io, cover bad, this is also a kind of situation of pilot pollution.
Ec/Io difference is generally thought of as <-12dB.
The effective Rake receiver quantity considering current mobile phone is 3, and therefore, the pilot tone of the pilot tone of the last 1 and semi-finals can be compared, if it is generally acknowledged, its difference is less than 3dB, then think to there is pilot pollution.
1, high FER.
Effectively can not utilize owing to there being strong pilot tone to exist, then constitute interference to other pilot tone, cause FER to raise, the network quality provided declines, or causes high cutting off rate.
2, call drop is switched.
If there are more than 3 strong pilot tones, then between these pilot tones, easily there is frequent switching, thus switching call drop may be caused.
3, capacity reduces.The region that there is pilot pollution increases due to interference, reduces effective covering of system, the capacity of system is affected.
Pilot pollution has a certain impact to network performance, and main manifestations is as follows:
(1) call completion ratio reduces: in the place of pilot pollution, cannot stablize and reside at a community, ceaselessly carry out Serving cell gravity treatment due to mobile phone, rise exhale in process and constantly can change Serving cell at mobile phone, easily occur to exhale unsuccessfully.
(2) cutting off rate rises: when there is the situation of pilot pollution, due to the dominant pilot that neither one is enough strong, in mobile phone communication process, and pingpang handoff can be relatively more serious, causes cutting off rate to rise.
(3) power system capacity reduces: when the situation of pilot pollution occurs, owing to there is interference, system reception sensitivity can be caused to promote.
The signal far away apart from base station cannot access, and causes power system capacity to decline.
(4) high BLER: have very large disturbed condition when pilot pollution occurs and occur, BLER can be caused like this to promote, cause speech quality to decline, message transmission rate declines.
Pilot pollution produces and mainly causes because signal between multiple sector disturbs each other.
Complexity due to wireless environment: the impact comprising topography and geomorphology, building distribution, street distribution, waters etc. each side, makes signal be very difficult to control, cannot reach desirable situation.
Pilot pollution mainly occurs in base station than in the urban environment of comparatively dense, and several typical region that pilot pollution easily occurs is: the region around high building, wide street, overhead, crossroad, waters.
Reason has:
1, cell layout is unreasonable.Irrational cell layout may cause subregion to occur covering cavity, and the strong quorum sensing inhibitor of multiple pilot tone appears in subregion.
So likely can cause large-area pilot pollution or coverage hole in network.Sometimes, because geographical environment is too complicated, the design phase is considered comprehensive not to the utmost, needs to be solved by adjustment in the network optimization stage
2, Gao Taigao hung by base station selection or antenna.Relative atural object around, most of region is around all in the horizon range of antenna, signal is propagated (especially in places such as outdoor, streets) within a large range, just at many regional effects other station to surrounding, the pilot pollution problem may be caused.
3, antenna bearingt arranges unreasonable.
If there is no appropriate design, partial sector may be caused to cover identical region simultaneously, form too much pilot tone and cover; Or because around atural object, as the impact etc. of building, causes certain region to have multiple pilot tone to exist; At this moment the adjustment carrying out antenna bearingt according to the situation of actual propagation is needed.
Special in the orientation of antenna is along street, its coverage Hui Yan street extends far away.
Like this, in the coverage of other base station along street, the pilot pollution problem may be caused.At this moment, may need to adjust the orientation of antenna or inclination angle etc.(1) wireless network networking is more flexible:
Wireless network uses wireless signal communication, and network insertion is more flexible, as long as there is the place of signal the network equipment can be linked into corporate intranet whenever and wherever possible.Therefore when corporate intranet application needs mobile office or instant demonstration, wireless network advantage is more obvious.
(2) upgrading of wireless network scale is convenient:
Wireless network terminal equipment access restricted number is less, compare the corresponding equipment of cable network interface, wireless router allows that multiple wireless terminal device is linked into wireless network simultaneously, and therefore when enterprise network scale is upgraded, wireless network advantage is more obvious.
Vision of the future is after technology of new generation has just released market, and higher technology application is is researched and developed in laboratory.The NTT DoCoMo company of Japan represents, the experimental network of 4G communication has been deployed in the research and development garden, Yokosuka of company, this network has assembled test base station and mobile terminal, NTT DoCoMo company also represents simultaneously, 4G communication service will be released in 2010, the speed of download of network can reach 100Mbps, and upload speed is 20Mbps.The test of the 4G communication network that AT & T company of the U.S. releases, allegedly can coordinate EDGE to carry out wireless uploading, and reach quick-downloading object by OFDM technology.AT & T company of the U.S. claims approximately also needs 5 years, and this technology could be issued; Have in a decade or so again, 4G really could put into commercial stage.Europe four mobile device manufacturers---Alcatel, Ericsson, Nokia and Siemens constitute wireless research forum of the world (WWRF), to study the later developing direction of 3G.WWRF estimates that 4G technology will start in 2010 to drop into application.This generation communication technology can by different WLAN and communication standard, mobile phone signal, and radio communication and television broadcasting and satellite communication combine, and such cellphone subscriber just can arbitraryly roam.At European Region, radio area loop and digital audio broadcasting are applied for its indoor (Indoor) and carry out relevant research and development, test event comprises the application of 10Mbps and MPEG image transmission, forth generation mobile communication technology will be then the extension of existing two research and development technologies, first technology starts indoor, then expands to outdoor mobile communication network gradually.A high-ranking official of Ericsson represents, the said firm can not reduce the budget of research and development forth generation wireless communication technique when economic depression, the director of the said firm represents simultaneously, the R&D work of the said firm has the perspective of 3-10, and temporary transient weak demand can not make the said firm slow down the speed of research.
International Telecommunication Union's Radiocommunications is also reached common understanding, and mobile communication system will be combined with other system, is that data transmission rate reaches 100Mbps before 2010.For more senior 3G system, ITU determines two standards simultaneously developing IMT-2000---improving the transmission rate of packet and audio files---by the WCDMA of Japanese NTT DoCoMo and J-Phone two company employing by the maximum downloading rate reaching 8Mbps of energy, and CDMA2000 system also will reach the speed of 2.4Mbps.Simultaneously externally the issue a statement frequency range of forth generation mobile communication of ITU not yet comes into question and formulation, but will be based on high band frequency spectrum in principle, also will use the relevant technology of microwave and frequency range in addition.
Forth generation mobile communication system should possess following several fundamental characteristics:
(1) service in complete set: every business such as personal communication, information system, broadcast and amusement will be combined into an entirety, and being supplied to user serves widely than ever and apply; The use of system will be more safe, convenient and more look after the individual character of user.
(2) immanent mobile access: in a 4 g system, the main access way that mobile access will be to provide the business such as speech, high speed information business, broadcast and amusement, people can be linked in system at any time, everywhere.
(3) subscriber equipment miscellaneous: mobile device miscellaneous for use is linked into 4G system by user.Exchanging between equipment with people is no longer only simply listen, say, see, can also be exchanged by other approach with user.This will be large easy for people to use, the particularly use of some disabled user.
(4) autonomous network configuration: the network of 4G system will be a Complete autonomy, adaptive network, and it can manage automatically, dynamically change the structure of oneself to meet the requirement of system change and development.
Access way is according to different applied environments, and the topological structure that WLAN (wireless local area network) adopts mainly contains four kinds, bridge connecting-type, access node connecting-type, HUB access type and non-stop layer type.
1, bridge connecting-type.This structure is mainly used in the interconnection between wireless or cable LAN.When two local area network (LAN)s cannot realize wired connection or use wired connection to have difficulties, bridge connecting-type can be used to realize point-to-point connection.Communication in such an embodiment between local area network (LAN) is realized by respective wireless bridge, and wireless bridge serves the effect of network path selection and protocol conversion.
2, access node connecting-type.This structure adopts mobile cellular communication net access way, communication between each mobile site is first got off by receives information by wireless receiving station (access node: AP) nearby, then the information received is passed to " mobile switching centre " by wired network, then is sent on all wireless receiving stations by mobile switching centre.At this moment in network coverage, this signal can be received Anywhere, and can roaming communication be realized.
3, HUB access type.In cable LAN, utilize HUB can set up Star Network structure.Wireless aps equally also can be utilized to set up the WLAN (wireless local area network) of hub-and-spoke configuration, and its working method is very similar with wired hub-and-spoke configuration.But General Requirements wireless aps should have function of exchange in simple net in a wireless local area network.
4, non-stop layer type structure.The operation principle of this structure is similar to the working method of wired peer-to-peer network.It requires all directly to carry out information exchange between any two websites in net.Namely each website is work station, is also server.
Networking products radio network product.
Wireless
1, versatility--the single platform of multiple Presence Protocol and application can be supported simultaneously;
The system of 2, simplification--easy to understand, operation and maintenance;
3, validity--save the extendible network of frequency spectrum and power.
Above key characteristic brings following advantage:
Total ownership cost can drop to minimum by the single wireless facility 1, being applied to whole factory;
2, connect multinomial mounted industrial protocol (as HART, OPC, Modbus etc.) simultaneously;
3, with existing industrial safety Realization of Product Seamless integration-;
4, the most reliable network--the longest uptime can be provided through on-site verification;
5, current the most scalable factory wireless system.
WLAN
WLAN communication system is selected generally to be used in same seat building as the another kind beyond wired lan.WLAN uses ISM (Industrial, Scientific, Medical) radio broadcasting band communication.The 802.11a standard of WLAN uses 5 GHz frequency ranges, and the maximal rate of support is 54 Mbps, and 802.11b and 802.11g standard uses 2.4 GHz frequency ranges, supports the speed of maximum 11 Mbps and 54 Mbps respectively.
WLAN is similar to wired ethernet, and they are all distribute MAC (Media Access Control) address from same address pool, and are all the network equipment layers appearing at operating system as ethernet device.Such as, ARP (Address Resolution Protocol) table is filled with WLAN MAC address and ethernet mac address.But WLAN and wired ethernet make a big difference at link layer.Such as, 802.11 standards use conflict avoidance (CSMA/CA) to replace the collision detection (CSMA/CD) of wired ethernet.And, with ethernet frame unlike, WLAN frame is identified.
Due to the smeared out boundary between WLAN work station, WLAN link layer has the agreement removing a region before transmission.For security consideration, Wired Equivalent Privacy (WEP) encryption mechanism of WLAN provides the level of security identical with cable network.40 bits or 104 bit keys and 24 random bit initial vectors combine in order to encryption and decryption data by WEP.WLAN supports two kinds of communication patterns: Ad Hoc pattern is used for need not using between small group work station the interior communication of the short time of accessing points, and all communications of Infrastructure pattern must pass through accessing points.Accessing points periodically broadcasts a service set identifier (SSID), and SSID is used for a wlan network and other networks to distinguish to come.
Most of available WLAN card is based on Intersil Prism or Lucent Hermes chipset.Compaq, Nokia, Linksys and D-Link card uses Prism chipset, and Lucent Orinoco card and Apple Airport use Hermes chipset.
4, Downtilt arranges unreasonable.
Inclination maneuver produces important impact by the signal at MPS process edge, thus affects the coverage of community.
When Downtilt design is unreasonable, also can receives its stronger covering signal in the place that should not cover, cause the interference to other region, will pilot pollution be caused like this, time serious, can call drop be caused.
5, pilot power arranges unreasonable.When base station dense distribution, little to the coverage asked, and pilot power arranges excessive, also may cause serious the pilot pollution problem.
6, coverage goal geographical position is higher.When the geographical position of a coverage goal is very high, as in high building, for the multiple BS around it all in horizon range, then easily form pilot pollution at this place.
Claims (6)
1. the effect in reduction cutting off rate of the soft hand-off of the method and apparatus CDMA of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention is obvious, but its switching competence exertion effect only between same carrier;
For the switching between different carrier frequency, direct-cut operation can only be adopted to realize;
The success rate of direct-cut operation is relatively low, and the direct-cut operation especially between the different carrier frequency of different base station, is easy to cause call drop;
The method and apparatus clean culture of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention is widely used in a network, on network, the data of the overwhelming majority are all transmit with the form of clean culture, and just general networking user does not know; You sending and receiving e-mail, browsing page time, must connect with mail server, Web server, what now use is exactly unicast data transmission mode.
2. the method and apparatus of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention adopts multicast, both can realize the data once transmitting all destination nodes, and also can reach the object only special object being transmitted to data;
The method and apparatus pilot signal of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention in WCDMA system for: soft handover, community select the scheduling algorithms such as gravity treatment, open Loop Power control, pilot pollution, it is corresponding without corresponding logic, transmission channel, is present in physical channel; CPICH is divided into two classes, PCPICH primary pilot channel, and each community only has 1 PCPICH, and for level detecting, channel estimating, launches in whole community; Another kind of is SCPICHD, secondary pilot channel, and there are some this channels each community, need not launch in whole community; Pilot signal is used for the phase reference of down channel;
In TFT, pilot channel power is constant is 29dBm, community threshold value: Ec>=-115dBm, Ec/I0>-20dB; For the channel of the unmodulated CF signal of base station sequential filming.
3. the method and apparatus pilot channel Pilot Channel communications term of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention, the unmodulated Direct Sequence Spread Spectrum Signal of each CDMA base sequential filming;
Pilot channel makes subscriber station can obtain the forward direction CDMA channel time limit, provides coherent demodulation phase reference, and provides signal strength signal intensity to compare means nationality to determine when to switch for each base station.
4. the method and apparatus content of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention: all-zero code, form: pilot channel is divided into the frame of 26.67ms
The method and apparatus firm power of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention, continues to launch, higher than the level of Traffic Channel by 4 to 6dB (being convenient to travelling carriage find), effect:
Help mobile phone capture systems
Multipath searching
Phase reference is provided, helps RAKE receiver to carry out Delay Estima-tion, do coherent demodulation
Mobile phone for measuring pilot channel during switching, carries out pilot frequency intensity and compares pilot channel Pilot Channel;
Pilot channel provides mark for travelling carriage, regularly, and phase reference (for coherent detection), and for signal strength signal intensity that power controls;
Pilot channel is the peak signal that community sends, and usually uses WC0;
Travelling carriage has the time acquisition pilot channel of 15 seconds; Pilot channel, not containing message, only contains the time shift short PN code for cell identification;
The method and apparatus pilot signal of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention is the Direct Sequence Spread Spectrum Signal of base station sequential filming non-modulated, it makes mobile phone can obtain the forward direction CDMA channel time limit, correlation demodulation phase reference is provided, and for each base station provides signal strength signal intensity to compare, mobile phone can determine when to switch;
When not having the situation of pilot beacon equipment, mobile phone roaming, under A base station, uses carrier frequency FA2 communication, and when mobile phone is gradually away from A base station, near B base station, B base station but only has carrier frequency FA1 to provide service;
The signal of the A base station FA2 that mobile phone receives is more and more weak, and B base station FA1 signal strengthens gradually, and the mode of direct-cut operation can only be adopted to switch, and can produce the interruption of 30 milliseconds; The success rate of the alien frequencies direct-cut operation of different base station is very low, is very easy to the phenomenon forming call drop;
If we have installed pilot beacon equipment in B base station, when mobile phone is under carrier frequency FA2 service, during from A base station movement to B base station, the pilot signal strength of base station near mobile phone can constantly detect; When T_Add parameter exceedes threshold value, mobile phone initiatively can send PSMM (power level measurement) message to A base station;
After A base station receives message, the configuration information of inquiry adjacent base station, finds that the pilot signal of the FA2 of B base station is actually dummy pilot signal, do not possess the possibility providing Traffic Channel, but the FA1 of B base station can provide service channel;
A base station sends EHDM (enhancement mode switches directed) message to mobile phone, and notice mobile phone is switched to carrier frequency FA1, handoff parameter is sent to mobile phone simultaneously;
Under mobile phone is first switched to the carrier frequency FA1 of A base station at once, be then switched to the carrier frequency FA1 of B base station from the carrier frequency FA1 of A base station according to the mode of soft handover, thus the switching ensured is carried out smoothly;
Pilot beacon technology due to effectively reducing cutting off rate, acting on clearly, being thus widely used after being proposed by CDMA technology standard owner Qualcomm;
According to the difference of occupation mode, following three classes roughly can be divided into:
Pilot beacon handoff functionality is just considered when design in base station;
When digital base band processor, from normal carrier frequency channel, extract pilot signal, for the transmitting of pilot beacon;
Can ensure that dummy pilot signal only includes pilot signal like this, and keep highly consistent with normal carrier frequency pilot signal;
This mode is obviously best implementation; But regrettably, the base station of many producers is not supported;
Especially microcell base station is representative, and in order to reduce cost, producer often saves the function of pilot beacon; Also be that two kinds of modes leave the market space below;
Pure pilot approach
Pure pilot approach adopts special channel generator to simulate pure pilot signal; Owing to only launching pure pilot tone, to the interference reduction on the carrier frequency at pilot beacon place;
But because pilot signal needs oneself to produce, the modem chip of some costlinesses be used, and internal structure more complicated;
Frequency shift mode
Frequency shift mode implements relatively simple, specifically from base station radio-frequency signal, all signals (comprising synchronous, paging and traffic channel signal) is all coupled to new carrier frequency and launches;
Pilot beacon equipment not only transmitting pilot signal, but also synchronizing signal, paging signal and traffic channel signal will be launched, similar to the coverage of base station for ensureing the coverage of pilot beacon like this, the power of required transmitting will keep synchronous with the transmitting power of base station;
The method and apparatus composition of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention and composition
Can effectively improve the success rate switched between different carrier frequency, extensive use in the network optimization, relatively more conventional is pilot beacon, and implementation has base station from presentation mode; Pure pilot approach; Easy frequency mode;
Pilot channel makes subscriber station can obtain the forward direction CDMA channel time limit, provides coherent demodulation phase reference, and provides signal strength signal intensity to compare means nationality to determine when to switch for each base station;
It is a part for descending power, with other down channel shared in common descending powers. the power due to transmitter is specified, therefore, the ratio that pilot power accounts for is large, will reduce the power of other down channel. and the traffic carrying capacity that they are supported will influencedly reduce;
The larger benefit of pilot power is that overlay area will be large; Smaller benefit is, the professional ability of support is large;
The method and apparatus pilot tone of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention is only present in descending, main effect:
Phase reference during UE Received signal strength;
Accessory terminal carries out channel estimating to dedicated channel;
Terminal carries out switching or community selection gravity treatment according to the pilot level received;
Pilot bits is present in the DPCCH of up-downgoing, effect:
Pilot bits is one group of bit numeral provided (frame synchronization), may be used for determination and the maintenance of frame synchronization, and also has the effect of channel estimating mutually.
Pilot pollution refers to that the intensity receiving 4 or more Ec/Io when mobile phone is all greater than the pilot tone of T_add, and wherein the intensity of neither one pilot tone greatly to occurring when can be used as dominant pilot;
Pilot pollution Ec/Io in pilot pollution district signal that is very poor and mobile phone Idle does not stop conversion to be caused mobile phone to rise to exhale difficulty; If now mobile phone is in talking state, due to the unexpected grow of certain pilot tone, it is not in the active set of travelling carriage, and at this moment mobile phone will call drop;
In TD-SCDMA, the effect of PCCPCH is substantially identical with the effect of the pilot tone in CDMA with WCDMA.
5. mainly by defining its pilot pollution to the research of PCCPCH in the method and apparatus TD-SCDMA of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention; The definition of strong pilot tone and enough strong dominant pilot is introduced in the pilot pollution of TD-SCDMA;
Namely, when certain a bit exists the too much strong pilot tone dominant pilot that but neither one is enough strong, namely pilot pollution is defined as;
In CDMA, when having four or more pilot signals in the Active Set of travelling carriage, (difference of the Ec/Io value of these pilot tones and optimal pilot is less than 6dB, and it is all large than T_ADD thresholding, and this wherein neither one signal can by force to being enough to become real dominant pilot), in these regions, other strong waveguide frequency signal not in travelling carriage Active Set there is suddenly the generation causing travelling carriage call drop phenomenon in handoff procedure, strong waveguide frequency signal becomes potential interference source, the origin of pilot pollution concept that Here it is;
One is thought, the signal branch number that existence receives is more than the quantity of Rake receiver, and these signals have exceeded given thresholding, these signals will cause serious interference to useful signal, Here it is pilot pollution, namely exceedes the number of the pilot tone number > Rake receiver of given thresholding; This given thresholding is generally taken as the settings of Tadd;
At present because an effectively point number for mobile phone is generally 3, therefore, if there is the strong component more than Tadd of more than 4, be then considered as there is pilot pollution;
One is thought, network signal level is fine, but Ec/Io is poor, and namely in a certain region, neither one has the prevailing pilot tone of sufficient intensity, and several covering pilot frequency intensity is suitable;
Rapid fading due to signal frequently switches when causing travelling carriage to converse between the Traffic Channel of different sector, very easily causes call drop;
If at this moment do not have the factor of external interference, illustrate that there is the signal from a lot of communities this area, thus cause very poor Ec/Io, cover bad, this is also a kind of situation of pilot pollution;
Ec/Io difference is generally thought of as <-12dB;
The effective Rake receiver quantity considering current mobile phone is 3, and therefore, the pilot tone of the pilot tone of the last 1 and semi-finals can be compared, if it is generally acknowledged, its difference is less than 3dB, then think to there is pilot pollution.
6. the method and apparatus height FER of the novel mapping pilot signal under clean culture and broadcast multi-broadcasting multiplexer mode of the present invention;
Effectively can not utilize owing to there being strong pilot tone to exist, then constitute interference to other pilot tone, cause FER to raise, the network quality provided declines, or causes high cutting off rate;
Switch call drop;
If there are more than 3 strong pilot tones, then between these pilot tones, easily there is frequent switching, thus switching call drop may be caused;
Capacity reduces; The region that there is pilot pollution increases due to interference, reduces effective covering of system, the capacity of system is affected;
Pilot pollution has a certain impact to network performance, and main manifestations is as follows:
(1) call completion ratio reduces: in the place of pilot pollution, cannot stablize and reside at a community, ceaselessly carry out Serving cell gravity treatment due to mobile phone, rise exhale in process and constantly can change Serving cell at mobile phone, easily occur to exhale unsuccessfully;
(2) cutting off rate rises: when there is the situation of pilot pollution, due to the dominant pilot that neither one is enough strong, in mobile phone communication process, and pingpang handoff can be relatively more serious, causes cutting off rate to rise;
(3) power system capacity reduces: when the situation of pilot pollution occurs, owing to there is interference, system reception sensitivity can be caused to promote;
The signal far away apart from base station cannot access, and causes power system capacity to decline;
(4) high BLER: have very large disturbed condition when pilot pollution occurs and occur, BLER can be caused like this to promote, cause speech quality to decline, message transmission rate declines.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105376867A (en) * | 2015-11-25 | 2016-03-02 | 南京中兴群力信息科技有限公司 | Method for improving air interface use ratio |
| CN107850658A (en) * | 2015-08-06 | 2018-03-27 | 高通股份有限公司 | Enhanced Passive Positioning with adaptive positive location |
| CN113475084A (en) * | 2019-02-27 | 2021-10-01 | 英国电讯有限公司 | Multicast assisted delivery |
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2013
- 2013-11-25 CN CN201310600975.3A patent/CN104660298A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107850658A (en) * | 2015-08-06 | 2018-03-27 | 高通股份有限公司 | Enhanced Passive Positioning with adaptive positive location |
| CN107850658B (en) * | 2015-08-06 | 2021-09-07 | 高通股份有限公司 | Enhanced passive positioning with adaptive active positioning |
| CN105376867A (en) * | 2015-11-25 | 2016-03-02 | 南京中兴群力信息科技有限公司 | Method for improving air interface use ratio |
| CN105376867B (en) * | 2015-11-25 | 2018-09-11 | 南京中兴群力信息科技有限公司 | A method of improving utilization rate of eating dishes without rice or wine |
| CN113475084A (en) * | 2019-02-27 | 2021-10-01 | 英国电讯有限公司 | Multicast assisted delivery |
| CN113475084B (en) * | 2019-02-27 | 2024-02-02 | 英国电讯有限公司 | Multicast assisted delivery |
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