JOINT ANALOG NETWORK CODING AND RELAY METHOD, BASE STATOIN AND USER EQUIPMENT FIELD OF THE INVENTION The present invention relates to the wireless cellular network communication, especially to high-rate, wideband wireless communication, e.g. 3GPP LTE based OFDM, and in particularly relates to a joint analog network coding and relay method, receiving and transmitting method and apparatus thereof. BACKGROUD OF THE INVENTION In a broad sense, a network coding is a multicast technique in which a node in the network encodes the received information and then forwards it out. The multicast is an important communication form in the network. When one or more nodes simultaneously send data to some other nodes, it often seeks help for the transfer by other nodes. In a conventional network, the node acting as a relay may only copy, amplify and forward the received signal, which is wasteful for the network resource sometimes. The network coding technique breaks such a limitation, allows the relay node to encode the received information, and recombines a plurality of received data packets in term of a specific algorithm and transmits them out. The network coding technique may significantly improve the data rate for the multicast. The information transmitted in a network may be called as a "stream" vividly. The maximum flow of the network is the maximum data transmission rate from a source node to a receiving node. The maximum flow for the broadcast is the maximum data transmission rate received by each of receiving nodes when a source node simultaneously transmits the same data to all of the receiving nodes. Theoretically, the maximum flow lies on the network topology structure, i.e. the connection relationship of the respective nodes and the bandwidth. The max-flow min-cut theorem which is famous in the graph theory may be employed to obtain the max flow from some source node to some receiving node in a given network. The network coding actually gets higher network efficiency in return for the node processing ability. In cellular wireless communication network, the base station has the fixed site and maximum transport power. So the coverage is invariable, and to improve the performance of UE at cell edge, some wireless communication techniques are implemented, for example, soft handover in CDMA systems. However, in general mobile communication systems such as UMTS Rel5 HSDPA and LTE, the macro diversity and soft combining of power contribution come from adjacent base station is not employed in order to achieve the independent, more fast and more flexible AMC, MAC scheduling and L1 HARQ. Therefore, a higher peak data transmission rate could be achieved when UE is near the site. But when UE is far from the site, e.g. at the cell edge, no so good technique could improve the service transmission performance so as to increase the spectrum efficiency. A wireless relay concept has been introduced in WiMax, but it has not been discussed in cellular networks. Since the present invention relates to a new application in the cellular network communication, there is no such a technical solution in the prior art. Fig. 1 illustrates the deployment of a cellular network with a wireless relay station. As an example, the relay station is located at the 1/3 distance to the cell edge. The relay may have the baseband processing function and can forward data coming from eNB. The relay transports the data at the same frequency as used by the eNB but time division multiplexing with the source. The relay may play several roles, among which, one is to amplify and forward the data, another is to decode and forward the data. In particularly, the scheduling of data receiving and transmitting in the relay is shown in Fig. 2 and Fig. 3. Fig. 2 shows the structure of relay in amplifying and forwarding used in a communication apparatus with a radio relay. As shown in Fig. 2, the relay station receives analog data form eNB via an antenna and the data is sampled and analog-to-digital converted (ADC); the ADC digital signal is symbolized; the symbolized digital level is amplified; and finally, the amplified digital level is digital-to-analog converted and shaped, and the shaped analog signal is forwarded via an antenna. Fig. 3 shows the structure of relay in coding and forwarding used in a communication apparatus with a radio relay. As shown in Fig. 3, the relay eceives analog data from eNB via an antenna and the data is sampled and analog-to-digital converted; the ADC digital signal is divided into two ways, one of which is subject to the actions shown in Fig. 2 to amplify the symbolized digital level, and the other of which is subject to demodulation, and decoding, and, after decoding, to a cycle redundancy check (CRC) and at the same time to encoding and modulating; if it passes the CRC check, the signal in the way of demodulating, decoding, encoding and modulating is DAC and shaped; or otherwise, if it does not pass the CRC check, the signal which is only amplified after the sampling and ADC is DAC and shaped; and finally the shaped analog signal is forwarded via an antenna. SUMMARY OF THE INVENTION The objective of the present invention is to propose a cellular network deployment by employing a joint analog network coding and a radio relay, i.e. network coding of a physical signal carrying information form a plurality of sources. It further discloses a transmission/reception scheme and the design for the transmitter/receiver. In accordance with a first aspect of embodiment of the present invention, there is provided a joint analog network coding and relay method for use in a cellular network with a wireless relay, which comprises steps of: receiving information signals from a plurality of base stations eNBs; sampling and Analog-to-digital converting the received signals; analog network coding the analog signal levels carrying the information from the plurality of eNBs; forwarding symbols after being analog network coded; and receiving the forwarded symbols and converting the symbols into the information signals. Preferably, said base station comprises a preceding relay station for forwarding data, and analog network coding is performed on the signals from said base station eNB and said preceding relay station. Preferably, said relay station time alternates alternately and carries the analog network coded information signals. Preferably, wherein said analog network coding comprises a physical signal summation. Preferably, said physical signal summation comprises a step of performing a weighting summation on signal blocks divided from the time slots. In accordance with a second aspect of the present invention, there is provided a reception method with a joint analog network coding and relay for use in a cellular network with a wireless relay, which comprises steps of: performing collaborative Multiple Input and Multiple Output operation on signals received from a plurality of eNBs or Relays; and a User Equipment decoding the signals received through said MIMO operation by joint detection technique. Preferably, said joint detection technique comprises a MIMO spatial de-multiplexing. Preferably, said joint detection technique comprises a successive interference cancellation SIC. Preferably, said decoding step is based on a Maximum-Likelihood ML method. Preferably, said decoding step is based on a Minimum Mean-Square Error algorithm together with Zero Forcing algorithm. Preferably, the Chase combining or IR combining is adopted for decoding after the UE receives the signals. In accordance with a third aspect of the present invention, there is provided a base station, which comprises: a sampling and ADC unit, for sampling and Analog-to-Digital converting the signals to be sent; a coding unit, for analog network coding the analog signal levels carrying information from a plurality of eNBs; a sending unit, for forwarding analog network coded symbols. Preferably, said coding unit implements the analog signal coding by employing a physical signal summation. Preferably, said coding unit implements the analog signal coding by employing a weighting summation on signal blocks divided from time slots. In accordance with a fourth aspect of the present invention, there is provided a user equipment, which comprises: a receiving unit, for receiving information from a base station; a decoding unit, for carrying out decoding by a joint detection technique; and a sending unit, for forwarding decoded signals. Preferably, said joint detection technique comprises a MIMO spatial de-multiplexing. Preferably, said joint detection technique comprises a successive interference cancellation SIC. Preferably, said decoding unit performs said decoding step based on a Maximum-Likelihood ML method. Preferably, said decoding unit performs said decoding step based on a Minimum Mean-Square Error algorithm together with Zero Forcing algorithm. Preferably, the Chase combining or IR combining is adopted by said decoding unit to carry out decoding after the UE receives the signals. In accordance with a fifth aspect of the present invention, there is provided a computer readable media having a computer executable program recorded thereon, where the program, when mounted on a computer, makes the computer execute the method according to the embodiments of the present invention . The beneficial effect of the present invention is that: the Relay in accordance with the embodiment of the present invention does the analog network coding, i.e. the physical signals carrying information of current slot/block analog network coded with previous ones are used to transmit the service data. In amplifying and forwarding data, UE receives the signal from eNB and relays it, and detects the slot by collaborative MIMO de-spatial MUX or successive interference cancellation; each time UE only reserves one slot hard decision, others' prior soft information are used for the next slot detection, which improves the UE receiving performance. In decoding and forwarding data, UE buffers the soft information of one block which is received from eNB, and then adopts the Chase combining or IR combining after receiving the data from relay to obtain the diversity gain. From the analysis in theory of the form of Channel Matrix united by eNB and Relay, It is found that the unite detection in receiver can provide at least the similar performance as traditional 2*2 transmit diversity. Additionally, the analog network coding in relay of two symbols obtains the similar performance of 3*3 MIMO. Even due to the larger SNR received from relay, the gain would be much more. The advantage of the present invention over the optimal prior art is that the joint analog network coding and wireless relay is a new application in wireless communication. Because in current HSDPA and LTE, AMC, MAC scheduling and L1 HARQ techniques all focus on the high peak rate of data transmission rate when UE is near the site, wireless relay join with analog network coding is a low-cost, low-complexity solution which could improve the service transmission performance when UE is at the cell edge, and increase the cell coverage. BRIEF DESCRIPTION OF THE DRAWINGS The advantages of the present invention will be apparent from the following detailed description taken in conjunction with the drawings, in which: Fig. 1 shows the deployment of cellular network with wireless relay; Fig. 2 shows the structure of relay in amplifying and forwarding used in a communication apparatus with a radio relay; Fig. 3 shows the structure of relay in coding and forwarding used in a communication apparatus with a radio relay; Fig. 4 shows the channel response vectors in the 2x2 Collaborative MIMO scheme; Fig. 5 shows the channel response vectors in the 2x1 Macro diversity scheme; Fig. 6 shows the flow chart of the analog network coding method in accordance with the embodiment of the present invention; Fig. 7 shows the physical processing structure of UE receiver, in which L1 structure of MIMO De-spatial MUX is employed; Fig. 8 shows the physical processing structure of UE receiver, in which L1 structure of SIC is employed; Figs. 9a and 9b show data transmission in amplifying and forwarding by employing analog network coding; Figs. 10a and 10b show data transmission in decoding and forwarding by employing analog network coding; Fig. 11 shows a schematic view of the communication apparatus with a radio relay in data amplifying and forwarding with analog network coding; Fig. 12 shows a schematic view of the communication apparatus with a radio relay in data coding and forwarding with analog network coding; Fig. 13 shows a relay receiver and transmitter system with two half-duplex relays; Fig. 14 shows a schematic view of data transmission in decoding and forwarding by employing analog network coding in a one slot relay; and Fig. 15 shows a schematic view of data transmission in decoding and forwarding by employing analog network coding in a two slot relay. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Now, detailed descriptions will be provided to embodiments of the present invention. The embodiments of the present invention will be described by referring to the drawings. The present invention provides a joint analog network coding and radio relay deployment. Two relays alternatively perform the time division to transmit a flow from a source together with analog network coding information, i.e. the physical signals carrying information of current slot/block analog network coded with previous ones. In a terminal receiver, a successive interference cancellation (SIC) and detection of the previous information from the base station may be applied. If there is more than one receiving antenna, a collaborative Multiple Input and Multiple Output (MIMO) operation of eNBs and Relays may be applied, in which the current information is used as one branch. From the analysis in theory of the form of Channel Matrix united by eNB and Relay, it is found that unite detection in receiver can provide at least the similar performance as traditional 2*2 transmit diversity. Additionally, the analog network coding in relay of two symbols obtains the similar performance of 3*3 MIMO. Even due to the larger SNR received from relay, the gain actually would be much more. The analog network coding method is applied to the analog signal in the system with relay, in which the analog signal carries information from a plurality of sources. The User Equipment may apply a joint detection technique, i.e. collaborative MIMO spatial de-multiplexing on base station and relay. Fig. 4 shows the channel response vectors in the 2x2 Collaborative MIMO scheme. Fig. 5 shows the channel response vectors in the 2x1 Macro diversity scheme. Fig. 6 shows the flow chart of the analog network coding and relay method in accordance with the embodiment of the present invention. As shown in Fig. 6, the method comprises the following steps of: receiving information signals from a plurality of base stations eNBs; sampling and Analog-to-digital converting (ADC) the received information signals; analog network coding the digitized levels of the analog signals carrying the information signals from the plurality of eNBs; forwarding the symbols after being analog network coded; and receiving the forwarded symbols and converting the symbols into the information signals. Said analog network coding refers to a summation of physical signals, i.e. signal coding in the level of an analog signal. Said summation of physical signals comprises a step of performing a weighting summation on the signal blocks divided from the time slots. Said base station eNB may also comprise the preceding relay station for forwarding data, and the analog network coding is performed on the signals from said base station eNB and said preceding relay station. Said relay station time alternates alternately and carries the analog network coded information signals. In accordance with another embodiment of the present invention, a reception method with a joint analog network coding and relay to be used in a cellular network with wireless relay, comprises the following steps of: performing collaborative Multiple Input and Multiple Output operation on the signals received from a plurality of eNBs or Relays; the User Equipment decoding the signals received through said MIMO operation by joint detection technique. Said joint detection technique comprises a MIMO spatial de-multiplexing. Said joint detection technique comprises a successive interference cancellation SIC. Said decoding method may be a Maximum-Likelihood ML or may be a Minimum Mean-Square Error algorithm together with Zero Forcing algorithm. The Chase combining or IR combining is adopted to carry out decoding after the UE receives the signals. In accordance with still another embodiment of the present invention, a base station comprises a sampling and ADC unit for sampling and Analog-Digital Converting the signals to be sent, a coding unit for analog network coding the analog signals carrying the information from a plurality of eNBs to symbols, a sending unit for forwarding the analog network coded symbols. Said coding unit implements the analog signal coding by employing a summation of physical signals. Said coding unit implements the analog signal coding by employing a weighting summation on the signal blocks divided from the time slots. In accordance with still another embodiment of the present invention, a user equipment comprises a receiving unit for receiving information from a base station eNB, a decoding unit for decoding the signals by a joint detection technique and a sending unit for forwarding the decoded signals. Said joint detection technique comprises a MIMO spatial de-multiplexing. Said joint detection technique comprises a successive interference cancellation SIC, Said decoding unit may perform the decoding step based on a Maximum-Likelihood ML. Said decoding unit may perform decoding step based on a Minimum Mean-Square Error algorithm together with Zero Forcing algorithm. The Chase combining or IR combining is adopted by said decoding unit to carrying out decoding after the UE receives the signals. The UE receiver and detection method in decoding and forwarding after channel response vector corresponding to Fig. 4 and Fig. 5 is analog network coded are explained by referencing to Fig. 7and Fig. 8. Fig. 7 shows the physical processing structure of UE receiver, jn which L1 structure of MIMO De-spatial MUX is employed and the user equipment comprises two antennas. As show in Fig. 6, when data is decoded and forwarded, the relay decodes the signal samples and performs cycle redundancy check; and then the data is re-encoded and forwarded to the UE, in which the transmission in the relay is one time slot latter than the transmission in the eNB. The user equipment in the receiving terminal may apply MIMO spatial de-multiplexing to the data signals received from the base station eNB and the relay. The UE buffers the soft information of one block which is received from eNB, and then adopts the Chase combining or IR combining after receiving the data from the relay to obtain the diversity gain. Fig. 8 shows the physical processing structure of UE receiver, in which L1 structure of SIC is employed and the user equipment UE comprises one antenna. As shown in Fig. 7, the UE in the receiving terminal may apply a successive interference cancellation (SIC) and detection together with the prior information from eNB. Figs. 9a and 9b show data transmission in amplifying and forwarding by employing analog network coding. As shown in Figs. 9a and 9b, two relays are taken as an example to explain the data relay in amplifying and forwarding data. The relay amplifies the signal sample and forwards it to UE, where the transmission in the relay is one slot delayed than the transmission from eNB. In Fig. 9a, the relay 1 only amplifies and forwards the odd data, the relay 2 only amplifies and forwards the even data, and the delay to the data applied by the relay is one slot. In Fig. 9b, the relay 1 carries out encoding in accordance with kSj+(1-k)Si+1(i=0,1,2...) and the relay 2 carries out encoding in accordance with kSj+(1-k)Sj+1(i=0,1,2...), where 0