KR20010102279A - Mobile station with two transceivers and inter-frequency methods performed therewith - Google Patents

Abstract

A mobile station for a wireless cellular or PCS system has two tunable transceivers, each transceiver having its own antenna, and each transceiver can be independently tuned to each other at the operating frequency of the base station of the system. The arrangement of the two transceivers makes it possible to perform the inter-precise soft handover method without using the compressed mode and to measure the inter-precise signal quality without using the slotted mode. Let's do it. Since the two antennas are spatially separated in distance, orientation, or polarization, the baseband signal of the transceiver is combined to take advantage of the antenna diversity effect when the transceiver is tuned to the same operating frequency. Both inter-precedence methods require that both the transceivers are tuned to the same current operating frequency and communicate with the current base station of the system, just prior to the commencement of the method, while one of the transceivers is tuned to another operating frequency, The other transceiver allows the current base station to maintain communication at the current operating frequency.

Description

MOBILE STATION WITH TWO TRANSCEIVERS AND INTER-FREQUENCY METHODS PERFORMED THEREWITH}

The method of performing inter-privacy handover is described by A. Baier et al. At the 7th IEE European Conference on Mobile and Personal Communications on December 13-15, 1993, "3rd Generation Cellular. MULTI-RATE DS-CDMA RADIO INTERFACE FOR THIRD-GENERATION CELLULAR SYSTEMS "is known from pages 255-260.

Handover is used in wireless cellular systems and PCS to move a mobile station from one area covered by one base station to another area during a call. While handover is generally adopted to move ongoing communication with a mobile station from a current base station to a new base station, it is also possible to hand over communication with the mobile station from one RF link to another RF link of the same base station. Do.

In a Code Division Multiple Access (CDMA) system, handover of mobile stations between base stations is such that both mobile stations simultaneously maintain communication with current and new base stations at the same frequency during a transient period, A mobile station, typically at a new frequency and / or to a new link in a new network, without a soft handover that receives the same data through a base station of B, or such a temporary period during which current and new RF links are maintained simultaneously. This switching can be either hard handover.

Unfortunately, inter-privilege handover may experience a break in the call causing annoyance and discomfort to the dropped party.

One way to improve the reliability of inter-precise handover is to use a temporary compressed mode, in which the data transmitted to the current base station at the current frequency F1 is transmitted by the mobile station at the second half of the frame. It is squeezed into the first half of the frame by doubling the instantaneous symbol rate R _INFO , while setting up tuning and communication at the new frequency of F2. While the compressed mode allows for a more gradual inter-concierge handover similar to soft handover, there may be a reduction in bit error (BER) while this mode is adopted by doubling the simultaneous symbol rate. Since the chip rate R _CHIP of the pseudo noise (PN) spreading code remains constant, doubling the symbol rate R _INFO will halve the spreading factor R _CHIP / R _INFO in each half of the frame, which is typically In compression mode, the power level of the transmission is compensated by increasing the power level of the transmission, and even though this temporary increase in the transmission power level in the compression mode increases the background interference applicable to all users. .

Slotted mode methods are known, but not necessarily, idle slots, which are generally sustained frames, are provided for communication between the mobile station and the base station at the current operating frequency so that the mobile station has another candidate operating frequency. It allows you to tune in, and to measure signal quality. Such a slot is preceded and followed by an active half frame, in which the instantaneous symbol rate is usually doubled to compensate for the lack of communication content in the slot. Power level also typically increases during the active half frame to compensate for half the spreading factor. It is also known that the reliability of transmission from and reception by the mobile station can be improved by antenna diversity, where the transceiver of the mobile station is connected to two or more spatially separated antennas.

The present invention relates to an inter-frequency method performed in or between a wireless cellular system and / or a personal communication system (PCS), wherein the present invention relates to a base station over an RF link at a current operating frequency. During communication, the mobile station is required to tune to another operating frequency. One such method is an object for achieving handover communicating with a mobile station over an RF link at a new operating frequency tuned by the mobile station, referred to herein as an "inter-frequency handover." Has Another of the methods has the purpose of allowing the mobile station to measure signal quality at a set of candidate frequencies different from the current operating frequency, referred to herein as " inter-precise signal quality measurement. &Quot; . Later methods provide information for handover decisions. The invention also relates to the structure of a mobile station in connection with the implementation of the inter-privacy method.

1 schematically illustrates a mobile station, which is arranged with two transceivers in accordance with the present invention, with a pair of wireless cellular networks, each of which is capable of communicating with a transceiver of the mobile station, respectively. It has a local base station of (local base station).

2A, 2B, and 2C illustrate the mobile station and the local base station of FIG. 1, with a communication link with the mobile station immediately before, during, and immediately after an inter-primary soft handover performed in accordance with the present invention. Generally describe each.

3A, 3B, and 3C illustrate the mobile station and the local base station of FIG. 1, a communication link with the mobile station immediately before, during, and immediately after the inter-precise signal quality measurement performed in accordance with the present invention. Generally describe each.

4 depicts communication to and from a mobile station for a time interval immediately before and immediately after inter-precedence soft handover, where time intervals A, B, and C are shown in FIG. 2A, respectively. Generally corresponds to the link descriptions depicted in FIGS.

Fig. 5 shows in general schematic the structure of a mobile station according to the invention, comprising first and second identical but independently controllable RF sections.

FIG. 6 is a schematic illustration of one of the same RF sections of FIG. 5; FIG.

It is an object of the present invention to provide a mobile station with the structure or functionality to participate in inter-precise soft handover in or between a wireless cellular system and / or PCS without using a compressed mode.

It is an additional object of the present invention to provide a mobile station with the structure or functionality to perform inter-precise signal quality measurement in a wireless cellular system and / or PCS without using slot mode.

It is an additional object of the present invention that the structure or functionality provided to a mobile station to participate in or perform the inter-precency method mentioned above may not be involved or is being performed by the mobile station. When used to improve the reliability and / or quality of the mobile station's communication.

The present invention provides two independently tunable transceivers, rather than one transceiver common to the mobile station, which allows the mobile station to participate in inter-precise soft handover without compressed mode and / or without inter-precon slot mode. Time signal quality measurements, and when two transceivers connected to each antenna spaced apart in distance, orientation or polarization are tuned to the same operating frequency, communication to and from the mobile station Is based on the viewpoint that it can be improved by the antenna diversity effect.

In accordance with the present invention, the mobile station so equipped is configured to steer the mobile station side of the inter-privacy method, where just prior to undertaking the method, both transceivers are tuned to the same current operating frequency, In communication with the current base station, and at an intermediate stage of the method, one of the transceivers is tuned to another operating frequency while the other transceiver maintains communication with the current base station at the current operating frequency.

The invention also relates to a stored program for the mobile station which operates the above-mentioned method and a method of operating the mobile station.

When the inter-conciliation method is a soft handover, during the intermediate stage, one of the transceivers tuned to another operating frequency, referred to herein as a new operating frequency, establishes an RF link for communication at the new operating frequency. After the intermediate stage, the other transceiver is tuned to the new operating frequency. On the other hand, when the inter-precedence method is soft handover, during the intermediate stage, one of the transceivers tuned to another operating frequency is used to measure the signal quality and the above of the transceivers after the intermediate stage Retune to the current operating frequency. Outside the intermediate steps of this inter-precedence method, both transceivers are tuned to the same frequency and the antenna diversity effect is used. One method of utilizing the antenna diversity effect is by combining baseband signals received from each transceiver and by linking baseband signals to be transmitted by each transceiver.

Other objects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.

The present invention is described herein with respect to a Direct Sequence Code Division Multiple Access (DS-CDMA) wireless cellular or type of PCS network utilizing multiple operating frequencies (e.g., CDMA 2000). Thus, there may be a handover requiring the mobile station to change from one operating frequency to another. Inter-precise handover may be required in other wireless cellular or PCS systems utilizing more than one radio channel, and the principles of the present invention may apply equally thereto. These other systems are under consideration: Analog Mobile Phone System (AMPS), Time Division Multiple Access (TDMA), Global System for Mobile Communications (GSM), Japan Personal Communication Device (PDC) systems, and Universal Mobile Telephone System (UMTS) third generation (3G) systems.

Referring to FIG. 1, there is shown a wireless cellular or PCS mobile station 10 capable of inter-precise soft handover, wherein the wireless cellular or PCS mobile station 10 is a first antenna coupled to a first transceiver 14. 12 and a second antenna 13 connected to the second transceiver 15. The transceivers 14 and 15 are tunable and independently of each other with respect to transmission and reception. In addition, antennas 12 and 13, if desired, are one of transceivers 14 and 15 that are capable of receiving RF, while others are transmitting RF at different operating frequencies, such as distance and / or orientation or polarization. There is enough space apart. The spacing and relative orientation or polarization of the antennas 12 and 13 are also sufficient, such that antenna diversity effects occur when the transceivers 14 and 15 are tuned to the same frequency and transmit or receive the same signal. The antenna diversity effect is used by diversity exploitation means 16. One of its modes of operation is to combine baseband signals received from transceivers 14 and 15, and to link baseband signals supplied to transceivers 14 and 15 for transmission. For example, the received baseband signals will be added together and the same baseband signal will be supplied to each transceiver for transmission. Another mode of operation of the diversity utilization means 16 is to use only the strongest signal received from the transceivers 14 and 15 and to supply the baseband signal only to the transceiver for which the strongest signal has been received.

The mobile station 10 also comprises an inter-presitivity method steering means 17 having a part 17a for steering soft handover and a part 17b for interlacing the signal quality measurement. The operation of the inter-precise method steering means 17 will become clearer as the discussion proceeds.

The mobile station 10 includes a second base station 32 from a wireless coverage area of the first base station 22 of the direct sequence code division multiple access (DS-CDMA) network 20, including when on a call. Can roam to a wireless coverage of, which may be the same network or different networks 30 of different DS-CDMA, as illustrated, so that an "inter-conciency" handover is required. This is from the bidirectional link L1 of the mobile station 10 with the local base station 22 of the network 20, at the operating frequency F1, to the local base station of the network 30, at the operating frequency F2. It must be switched or transferred to the bidirectional link L2 of the mobile station 10 with 32. As generally illustrated, the transceivers 14 and 15 are independently operable at either frequency F1 or F2, allowing them to operate independently on the link L1 or link L2, respectively. However, the course of events in inter-privacy handover is more apparent from FIGS. 2A-2C. As shown in FIG. 2A, just before inter-precision handover, both transceivers 14 and 15 take advantage of the antenna diversity effect, for example, to both transceivers 14 and 15. By adding the signal received by, or using only one signal with better signal quality, it operates over the link L1 to the current local base station 22 at frequency F1. Then, as shown in FIG. 2B, after receiving the handover command from the local base station 22, the transceiver 15 tunes to the frequency F2 and the new local base station 32 over the link L2. Start working. Once the communication between the transceiver 15 and the new local base station 32 is stable, the transceiver 14 is also switched to frequency F2, resulting in the position shown in FIG. 3C, where the transceiver ( 14,15 are both operating as a new local base station 32 via link L2 at frequency F2 using the antenna diversity effect.

As is well known, before receiving a handover command from the local base station 22 designating the base station 32 as the recipient of the handover, the mobile station 10 includes F2 at other candidate operating frequencies, including: For example, it is necessary to make inter-precise signal quality measurements of pilot strength and send this information to the current base station 22. The use of two independently tunable transceivers 14 and 15 eliminates the need for slot mode, where idle slots are used between the leading and trailing active frame portions or partial frames. Appears to be inserted, the mobile station makes a signal quality measurement during the slot. A concomitant increase in the instantaneous symbol rate in the idle slot and the leading and following frame portions is not necessary. In order to tune to the candidate frequency and measure the pilot strength, inter-precise signal quality measurements can be made using one of the transceivers, for example transceiver 15, and another transceiver, for example a transceiver ( 14) maintains communication with the current base station at the current operating frequency, thus, as shown in FIG. 3A, just before the inter-precision handover, both the transceivers 14 and 15 utilize the antenna diversity effect. Thus, for example, by adding signals received by both transceivers 14 and 15 or by using only one signal with better signal quality, the current local base station over link L1 at frequency F1. It is working as (22). Thus, as shown in FIG. 2B, the transceiver 15 is tuned to frequency F2 and measures the strength of the pilot received at that frequency from base station 32 as an indication of signal quality. Once the signal quality measurement is made, the transceiver 15 is switched back to frequency F1, resulting in the position shown in FIG. 3C, where both the transceivers 14 and 15 take advantage of the antenna diversity effect. Thus, at frequency F1, it is currently operating back to local base station 22 via link L1.

Returning to FIG. 1, at the degree of detail shown, networks 20 and 30 appear conventional.

For illustration, a network 20 is shown, with two base stations 22 and 24, a base station controller 26 controlling the plurality of base stations 22 and 24, and a network controlling the network 20. It is shown to include a controller 28. Similarly, network 30 includes two base stations 32, 34, a base station controller 36 that controls the plurality of base stations 32, 34, and a network controller 38 that controls network 20. It is shown. The network controller is connected by a communication link 40, and each network controller is also connected to a public switched telephone network (PSTN) 42.

4 depicts the communication between the mobile station 10 and the local base stations 22 and 32 in more detail, where BS1 corresponds to base station 22 and BS2 corresponds to base station 32. As shown, initially a first downlink data frame DL_Data_1, a first uplink data frame (e.g., representing time division duplex voice traffic) between the current local base station 22 and the transceivers 14 and 15, for example. UP_Data_1, a second downlink data frame DL_Data_2, and a sequence of second uplink data frame UP_Data_2, and specify a frequency F2, otherwise identify a new base station 32, There is a downlink handover command (Handover_Cmd) from the base station 22 to the transceivers 14 and 15. As is the case with conventional ones, the handover decision is made in an infrastructure system 20 that utilizes the inter-precise signal quality measurement previously provided by the mobile station 10, and the base station 32 is also It is made to be aware of handovers impinging over the link 40 between the systems 20 and 30. At this point, the transceiver 15 switches its operating frequency to F2 and sends a request for acknowledgment (RACH) to the new base station 32, which ultimately sends a signal Info. In response, the transceiver 18 then sends an uplink signal Handover_Com to the new base station 32 indicating that the handover is complete. Until the completion of the handover is signaled, the transceiver 14 remains in communication with the current base station 22, and data, for example, as shown, third uplink data frame UP_Data_3, third Downlink data frame DL_Data_3, fourth uplink data frame UP_Data_4, fourth downlink data frame DL_Data_4, fifth uplink data frame UP_Data_5, fifth downlink data frame DL_Data_5, and sixth Received and sent an uplink data frame UP_Data_6. Then, while transceiver 14 tunes to frequency F2, transceiver 15 receives a seventh downlink data frame DL_Data_7. Thereafter, between the new local base station 32 and the receivers 14 and 15, for example, the seventh uplink data frame UP_Data_7, which again represents time division duplex voice traffic, the eighth downlink data frame DL_Data_8 ), The eighth uplink data frame UP_Data_8, and the last sequence of the ninth downlink data frame DL_Data_9.

The mobile handset 10 is schematically illustrated in FIG. 5, where the first transceiver 14 generally includes a combination of the first RF section 42 and the baseband section 50, so that the second The transceiver 15 generally includes a combination of a baseband section 50 and a second RF section 46 that is identical to the first RF section 42. Baseband section 50 includes a digital signal processor (DSP) 50a, a microprocessor 50b, a nonvolatile memory or a ROM 50c, at least some of which are programmable and inter-precise Firmware for configuring the programs and data for operation of the DSP 50a and the microprocessor 50b, including steering the mobile station side of the soft handover and the inter-precise signal quality measurement prior to the handover ( firmware) and mainly volatile random access memory for temporarily storing data. The received and demodulated signal R is fed from the RF section 42 and 46 to the baseband section 50, respectively, via analog-to-digital converters 50e and 50f, respectively. The DSP 50a performs despreading and decoding operations on the demodulated signal, respectively, in a well known manner by applying an associated pseudo noise (PN) in the relevant phase. Similarly, the spread spectrum encoded signal T generated by the DSP 50a is modulated and transmitted on the carrier via the first RF section 42 via the digital-to-analog converters 50g and 50h, respectively. Supplied to the second RF section 46. In addition, the command signal C, such as a tuning command, is respectively transmitted from the baseband section 50 to the first RF section 42 and the second RF section 46 via digital-to-analog converters 50i and 50j, respectively. Supplied by.

The mobile station 10 communicates with the baseband section 50 to communicate with a numeric keypad 51, a driver 52 for a display 53, for example an LCD screen, a microphone 54 and a speaker. It further includes (55). Microphone 54 communicates with baseband section 50 via analog-to-digital converter 50k, and baseband section 50 communicates with speaker 55 via digital-to-analog converter 50l. do.

An identical but independently controllable RF section corresponding to the first and second RF sections 42 and 46 is shown in FIG. 6. The RF section includes a diplexer 60 connected to an antenna 12 or 13, where an application is possible, the diplexer 60 from the output of a power amplifier (PA) 62, the antenna Receives an RF spread spectrum communication signal to be transmitted by and supplies an RF spread spectrum communication signal received by the antenna to an input of a low noise amplifier (LNA) 64. The modulator 66 preferably has a zero IF structure (not shown), and the baseband section 50 receives a baseband spread spectrum communication signal from a voltage controlled oscillator (VCO) or frequency synthesizer 68. ) Receives an RF carrier signal and supplies an RF spread spectrum communication signal to the input of power amplifier 64. Similarly, demodulator 67 also preferably has a zero IF structure (not shown), with an RF spread spectrum communication signal from the output of low noise amplifier 64 and an RF carrier signal from oscillator or synthesizer 68. Receive and feed a baseband spread spectrum communication signal R to baseband section 50.

It is now understood that the object of the present invention has been met. While the invention has been described in particular detail, it is also to be understood that many variations are possible within the spirit and scope of the invention. In interpreting the appended claims, it should be understood that:

a) The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim;

b) The word "a" or "an" preceding a device does not exclude the presence of a plurality of such devices;

c) any reference signs in the claims do not limit their scope;

d) "Attention" may be represented as a structure or function in which hardware or software of the same item is implemented.

The present invention is used in, for example, an inter-precision method performed in or between a wireless cellular system and / or a personal communication system (PCS).

Claims (13)

As a mobile station for a wireless cellular or PCS system 20, The mobile station 10 comprises two tunable transceivers 14 and 15, which can be independently tuned to each other at the operating frequencies of the base stations 22 and 32 of the system, Lee Dong-guk. The method of claim 1, Two antennas connected to each of the two transceivers 14, 15 spaced apart in distance, orientation or polarization, Selectively combine the baseband signals received by the transceivers 14 and 15 to exploit the antenna diversity effect when the transceivers 14 and 15 are tuned to the same operating frequency. Diversity effect means 16 for selectively linking baseband signals to be transmitted supplied to the transceivers 14 and 15; In addition, a mobile station. 3. A method as claimed in claim 1 or 2, further comprising means for steering a mobile station side of an inter-frequency method, Here, just prior to the commitment of the method, both transceivers 14 and 15 are tuned to the same current operating frequency and in communication with the current base station 22 of the system, in one stage of the method. And one (15) of the transceivers is tuned to another operating frequency while the other transceiver (14) maintains communication with the current base station (22) at the current operating frequency. 4. The method of claim 3, wherein the inter-precision method is such that during the stage one of the transceivers 15 tuned to another operating frequency, referred to herein as a new operating frequency, communicates at the new operating frequency. And establishes an RF link (L2), and after the stage, the other transceiver (14) is tuned to the new operating frequency. 4. The method of claim 3, wherein the inter-precision method is used during the stage, one of the transceivers (15) tuned to another operating frequency, to make a signal quality measurement (17b), and after the stage, One of the transceivers (15) is tuned back to the current operating frequency. As a stored program for a mobile station 10 for a wireless cellular or PCS system 20, The mobile station has two tunable transceivers 14, 15 that can be independently tuned to each other at the operating frequencies of the base stations 22, 32 of the system, The program is configured to steer the mobile station side of the inter-privacy method, where just before the initiation of the method, both transceivers 14 and 15 are tuned to the same current operating frequency and the system 20 Is in communication with the current base station 22, wherein, in one stage of the method, one of the transceivers 15 is tuned to another operating frequency, while the other transceiver 14 is at the current operating frequency. To maintain communication with 22, Stored programs. 7. The method of claim 6, wherein the inter-conciliation method further comprises, during the stage, that one of the transceivers 15 tuned to another operating frequency, referred to above as the new operating frequency, communicates at the new operating frequency. Set up an RF link (L2), after which the other transceiver (14) is tuned to the new operating frequency. 7. The method of claim 6, wherein the inter-precision method is used during the stage, one of the transceivers (15) tuned to another operating frequency, to make a signal quality measurement (17b), after which the stage: Stored program, wherein one of the transceivers is tuned back to the current operating frequency. 9. The mobile station according to any one of claims 6 to 8, wherein the mobile station (10) comprises two antennas (12, 13) connected to each of the two transceivers (14, 15), The antennas 12 and 13 are spatially separated in distance, azimuth or polarization, and the stored program is adapted to use the antenna diversity effect 16 when the antenna is tuned to the same operating frequency. And selectively combine the baseband signals received by (14, 15), and selectively link the baseband signals to be transmitted supplied to the transceiver. A method of operating a mobile station 10 for a wireless cellular or PCS system 20, The mobile station 10 has two tunable transceivers 14 and 15 which can be independently tuned to each other at the operating frequencies of the base stations 22 and 32 of the system, The method of operation is the mobile station side of the inter-privacy method, where just prior to the initiation of the method, both transceivers 14 and 15 are tuned to the same current operating frequency and the current base station 22 of the system. In one stage of the method, one of the transceivers is tuned to another operating frequency while the other transceiver 14 communicates with the current base station 22 at the current operating frequency. Maintained, How a mobile station works. 12. The method of claim 10, wherein the inter-conciliation method further comprises, during the stage, that one of the transceivers 15 tuned to another operating frequency, referred to above as a new operating frequency, for communication at the new operating frequency. Establish an RF link (L2), and after the stage, the other transceiver (14) is tuned to the new operating frequency. 11. The method of claim 10, wherein the inter-precision method is used during the stage, one of the transceivers (15) tuned to another operating frequency, to make a signal quality measurement (17b), and after the stage, One of the transceivers (15) is tuned back to the current operating frequency. 13. The mobile station (10) according to any one of claims 10 to 12, wherein the mobile station (10) comprises two antennas (12, 13) connected to the two transceivers (14, 15), respectively. ) Are spatially separated in distance, azimuth, or polarization, and the method of operation is such that the transceivers 14, 15 are adapted to take advantage of the antenna diversity effect when the transceivers 14, 15 are tuned to the same operating frequency. And selectively link the baseband signals received by < RTI ID = 0.0 >) < / RTI > and selectively link the baseband signals to be transmitted supplied to the transceivers (14, 15).