WO1999022533A1

WO1999022533A1 - Method and base station for providing user signals for measuring power in a radiocommunications system

Info

Publication number: WO1999022533A1
Application number: PCT/DE1998/003063
Authority: WO
Inventors: Gerhard Ritter
Original assignee: Siemens Aktiengesellschaft
Priority date: 1997-10-27
Filing date: 1998-10-20
Publication date: 1999-05-06
Also published as: DE19747455C1; AU1482299A

Abstract

The invention relates to a method and a base station for providing user signals for measuring power in a radiocommunications system, the radio interface being organised according to a CDMA user separation method. At least two user signals which are spread with individual spread codes are overlaid to give a sum signal. The user signals are transmitted by a base station. The transmission power for the individual user signals may vary, however the transmission power for the sum signal is kept constant at certain times so that the power can be measured by a receiving radio station.

Description

description

Method and base station for providing subscriber signals for power measurement in a radio communication system

The invention relates to a method and a base station for providing subscriber signals for power measurement in a radio communication system, in particular in a mobile radio system.

The construction of digital radio networks is described in J. Oudelaar, "Evolution towards UMTS", PIMRC 94, 5th IEEE International Symp. On Personal, Indoor and Mobile Radio Communications, The Hague, NL, Sept. 18-22 1994, pp. 852-856, and M. Lenti, H. Hageman, "Paging in UMTS", RACE Mobile Telecommunications orkschop, Vol. 1, Amsterdam, NL, 17th-19th May 1994, pp.405-410.

The currently existing second generation mobile radio system GSM (Global System for Mobile Communications) is a mobile communication system with a TDMA component for subscriber separation (Time Division Multiple Access). According to a frame structure, user information of the subscriber connections is transmitted in time slots. The user information is transmitted in blocks. Channels adapted to the time structure of the frame structure (BCCH - Broadcast Control Channel) for transmitting organizational information are also known from the GSM mobile radio system. This organizational information can provide information about the

Location area, radio cell, radio channel configuration and services that are supported within the radio cell. These channels with the organizational information are transmitted with a constant, maximum transmission power, so that a mobile station can perform power measurements and a most suitable base station in the area can determine the location for the transmission of the useful information in the upward direction.

A mobile communication system is known from DE 195 49 148.3, which uses CDMA subscriber separation (CDMA - Code Division Multiple Access) and uses a JD method (JD - Joint Detection) at the receiving end in order to use a spreading code of several subscribers to make improved detection of the transmitted useful information. ^'

DE 44 30 349 C2 discloses a method for measuring the power of an interferer signal which is received together with a carrier signal in a radio channel of a mobile radio network and forms an aggregate signal there. Here, a power of the interferer signal in the selected time slot is determined from a ratio formed between an average power of a time slot and an average power of a compressed network-specific signal section.

The invention is based on the object of specifying a method and a base station for a power measurement by a radio station that is as simple and flexible as possible for a radio communication system with a CDMA subscriber separation method.

The object is achieved according to the invention by the method according to the features of claim 1 and by the base station according to the features of claim 9. Advantageous developments of the invention can be found in the subclaims.

According to the invention, the method for providing subscriber signals for power measurement in a radio communication system, in which the radio interface according to a

CDMA participant separation process is organized, at least two participants spread with individual spreading codes mersignale superimposed to a sum signal. The subscriber signals are transmitted by a base station, the transmission power for the respective subscriber signals may vary, but the transmission power of the sum signal is kept constant at certain times for the power measurement to be carried out by a receiving radio station.

The method according to the invention advantageously enables the transmission power of the subscriber signals to be varied individually, for example depending on the distance of the radio station from the base station and / or on the transmission conditions on the radio interface. For power measurements by the radio station, therefore, no special channels need to be provided, which are transmitted with a constant, maximum transmission power. Due to the prerequisite according to the invention that the total power of the subscriber signals is kept constant at certain times, the radio station can evaluate these subscriber signals during these times and perform a power measurement to determine the most suitable base station for transmitting information in the vicinity of the radio station.

In a first embodiment of the invention, the radio interface is additionally organized according to a TDMA subscriber separation method, the sum signal being transmitted in a time slot. This embodiment advantageously enables the method according to the invention to be implemented in a simple manner in a third-generation mobile radio system based on the known GSM system. Furthermore, the structure of the transmission of user and organizational information can advantageously be adopted by this system.

According to a further development, the sum signal is sent with a maximum transmission power. As a result, the radio station can advantageously use the strongest signal on the radio Determine the interface and use it to carry out the power measurement.

Based on the TD / CDMA subscriber separation method according to the first embodiment, in a third embodiment a group of subscriber signals is assigned to time slots in such a way that the transmission power of the sum signal in each time slot results in a specific desired transmission power. This embodiment of the invention advantageously enables largely the transmission power for the individual

Varying subscriber signals freely without keeping the transmission power of the sum signal constant at certain times and thereby possibly negatively influencing the reception conditions on the radio station side.

By assigning the subscriber signals to the time slots after the requirement of fulfilling a specific target transmission power, the radio station can carry out a power measurement at practically any time in each time slot. According to a continuation of the previous embodiment of the invention, the target transmission power is defined by the limited maximum reception dynamics of the reception path of the radio station. The nominal transmission power does not have to correspond to the maximum transmission power, as a result of which the transmission device in the base station can be operated with a constant transmission power, and the components m of the transmission device can be designed and dimensioned in an optimal manner for this transmission power.

In a further embodiment of the invention, the

Subscriber signals formed from at least one data part, in which at least one midamble is embedded, useful information for the radio station or organizational information about the radio cell illuminated by the base station, the channel structure and / or options supported within the radio cell being transmitted in the data part. This structure of the subscriber signals corresponds to below the requirement for the transmission of the subscriber signals in time slots, the known structure in the GSM mobile radio system. Compatibility with this globally widespread mobile radio system can thereby advantageously be ensured, the structure of the organizational information being able to be adopted without major changes.

Based on this organizational structure of the subscriber signals, in a further embodiment of the invention only the transmission power of the sum signal of the midamble can be kept constant at certain times. With this configuration, the transmission power for the transmission of the data part can be varied freely by the radio station, regardless of the power measurement. The radio station only performs the power measurements when the midamble is being transmitted.

A further solution to the regulation of the transmission power includes a further embodiment of the invention, in which a correction factor is transmitted in the middle that indicates the respective transmission power for the subscriber signals. This correction factor enables the radio station to calculate the transmission power sent by the base station for the sum signals and to carry out a power measurement based on this calculation. In this case, for example, the transmission power of the sum signals can advantageously vary in the individual time slots, as a result of which an assignment of the subscriber signals to the time slots can be dispensed with, provided that a certain desired transmission power is used, in accordance with a described embodiment of the invention.

Embodiments of the invention are explained in more detail with reference to the accompanying drawings.

Show 1 shows a block diagram of a radio communication system, in particular a mobile radio system, FIG. 2 shows a schematic representation of the structure of the radio interface, FIG. 3 shows a schematic representation of the structure of a radio block in a time slot, FIG. 4 shows a schematic representation of the transmission power for the subscriber signals in the time slots of a Time frame, and FIG 5 is a schematic representation of the allocation of the subscriber signals to the time slots.

The structure of the radio communication system shown in FIG. 1 corresponds to a known GSM mobile radio network which consists of a multiplicity of mobile switching centers MSC which are networked with one another or which provide access to a fixed network PSTN. Furthermore, these mobile switching centers MSC are each connected to at least one base station controller BSC. Each base station controller BSC in turn enables a connection to at least one base station BS. These base stations BS are radio stations which can establish communication connections to further radio stations, in the case shown, to a mobile radio station MS via a radio interface. The functionality of this structure can be transferred to other mobile communication systems in which the invention can be used.

1 shows, by way of example, two radio connections for the transmission of subscriber signals tsigl and tsig2 between the base station BS and two radio stations MS. A third receiving radio station MS, for example, would like to set up a radio connection for a communication connection to a base station BS in the vicinity of their location and for this purpose carries out a power measurement based on the subscriber signals tsigl, tsig2 sent by the base station BS to the two further radio stations MS in order to select the most suitable base station BS for the connection establishment.

The base station BS is connected to an antenna device AE which e.g. consists of three individual emitters. Each of the individual radiators radiates in a sector of the radio cell supplied by the base station BS. However, it is alternatively also possible to use a larger number of individual radiators (according to adaptive antennas), so that spatial subscriber separation using an SDMA method (SDMA - Space Division Multiple Access) can also be used.

In the base station BS, among other things, a signal processing device SVE is implemented, in which the subscriber signals tsigl, tsig2, which are spread by individual spreading codes cl or c2 according to a CDMA subscriber separation method and superimposed to form a sum signal, are implemented. The signal processing device SVE makes the coded subscriber signals tsigl, tsig2 available to a transmission device SE which is connected to the antenna device AE. A control device ST for controlling the transmission powers with which the subscriber signals tsigl, tsig2 are transmitted is connected to the transmission device SE. The control device ST controls the transmission device SE in such a way that the transmission power E of the sum signal is kept constant at certain times so that the radio station MS can perform a power measurement.

The structure of the radio interface is shown in FIG 2. According to a TDMA component, a division of a frequency range into several time slots ts, for example 8 time slots tsl to tsδ, is provided. In the example, the radio interface has, in addition to the time division multiplex (TDMA), a code division multiplex component (CDMA). In addition, according to an FDMA (Frequency Division Multiple Access) component, the radio communication system has several frequency ranges with one oc MI- ¹

Cn o Cπ O Cπ o Cπ

Values of the correction factor kf from 0 to 10 are represented. This correction factor kf can be a defined multiplication factor which specifies with which transmission power or with how many times the smallest transmission power level the radio blocks are transmitted in the respective time slot tsl by the base station BS. Taking this correction factor kf into account, the radio station MS can determine the precise transmission power E of the radio blocks in the time slot tsl and incorporate them into the power measurement in order to achieve a more precise result. In the example in FIG. 3, the base station BS sends the data part dt spread with the spreading code cl with useful information d of the subscriber signal tsigl with a transmission power El that corresponds to a correction factor kf-5. The data parts dt with the useful information d transmitted to the radio block of the subscriber signal tsιg2 and spread with the spreading code c2, on the other hand, are transmitted with a transmission power E2, which corresponds to a correction factor kf = 2, and the data part dt spread with the spreading code c3 Organization information oi with a transmission power Eoi, which corresponds to a correction factor kf = 7, is sent.

The transmission of a radio block with a data part dt with organization information oi m a time slot tsl can also be used for the transmission power Eoi for this radio block to be so large that the transmission power of the sum signal is summed, consisting of, for example, the subscriber signals tsigl and tsιg2 and the Radio block with the organizational information oi, m corresponds to the time slot tsl a maximum transmission power Emax. If the transmission power for the subscriber signals tsigl and tsιg2 changes, the transmission power for the radio block is varied and adapted accordingly with the organizational information oi. Additional identification of the transmission power E used for the individual radio blocks by means of a correction factor kf can thus be omitted. The radio station MS determines, as already described above, the signal co cυ IΌ NJ P ¹ P ¹

Cπ o Cπ O Cπ o cn rt cn o

P d et

Φ l-i

-3

Φ

P cn

Φ

N d

"> et

PJ

EP et

P

Φ

CΛ d

3

Φ et

Φ

H

CΛ

Φ d

ct

Φ

P cn rt d d

LP

Φ d w

P>

E2, ... E8 of the subscriber signals each corresponds to a nominal transmission power Esoll. Since the transmission powers El, E2, ... E8 of the subscriber signals tsigl, tsig2, ... tsigδ due to the movement of the participants, respectively. of the radio stations MS, are constantly updated, the control device ST and the signal processing device SVE must dynamically change the assignment of the subscriber signals tsigl, tsig2, ... tsigδ to the time slots tsl, ts2 and ts3 while fulfilling the target transmission power Esoll. The radio station MS can thus access all time slots in the time frame tf in order to carry out a power measurement. A radio block with organizational information oi can be transmitted indiscriminately in a time slot tsl, ts2, ... ts8 of the time frame tf.

In FIG 5 following this assignment rule are the

Time slot tsl is assigned to subscriber signals tsigl and tsig2 with transmission powers E1 and E2, whereas time slot ts2 is assigned to subscriber signals tsig3, tsig5 and tsigδ with respective transmission powers E3, E5 and E8. In contrast, the subscriber signals tsig4, tsigβ and tsig7 with the transmission powers E4, E6 and E7 are transmitted in the time slot ts3. The sum of the transmission powers E1, E2 or E3, E5, Eδ or E4, E6, E7 corresponds to the target transmission power Esoll.

Claims

claims

1. Method for providing subscriber signals (tsigl, tsig2, .. tsign) for power measurement in a radio communication system, in which the radio interface is organized according to a CDMA subscriber separation method, at least two being spread with individual spreading codes (cl, c2) Subscriber signals (tsigl, tsig2) are superimposed into a sum signal (sumsig), the subscriber signals (tsigl, tsig2) are sent by a base station (BS), the transmission power for the respective subscriber signals (tsigl, tsig2) being able to vary, the transmission power (E) of the sum signal (summed), however, is kept constant at certain times for performing the power measurement by a receiving radio station (MS).

2. The method according to claim 1, wherein the radio interface is additionally organized according to a TDMA subscriber separation method, the sum signal (sumsig) being transmitted in a time slot (tsl).

3. The method of claim 1 or 2, wherein the transmission power of the sum signal (sumsig) corresponds to a maximum transmission power (Emax) of the base station (BS).

4. The method according to claim 2 or 3, in which a group of subscriber signals (tsigl, tsig2, .. tsign) is assigned to time slots (tsl, ts2, .. ts8) such that the sum of the individual transmission powers (El, E2, .. En) results in a certain target transmission power (Esoll) in each time slot (tsl, ts2, .. tsδ).

5. The method according to claim 4, wherein the target transmission power (Esoll) is defined by a processable E p- fangsdyna_mik of the radio station (MS).

6. The method according to any one of the preceding claims, wherein the subscriber signals (tsigl, tsig2, .. tsign) are each formed from at least one data part (dt), in which at least one middle amble (a) with known symbols is embedded, in which Data part (dt) useful information (d) and / or organizational information (oi) are transmitted via the radio cell illuminated by the base station (BS), via the radio channel configuration and / or via services supported within the radio cell.

7. The method according to claim 6, wherein only the transmission power (E) of the sum signal (su sig) of the midamble (ma) is kept constant at certain times.

8. The method according to claim 6 or 7, in which a correction factor (kf) is transmitted in the midamble (ma), which corrects the respective transmission power (El, E2, .. En) for the subscriber signals (tsigl, tsig2, .. tsign) indicates.

9. base station (BS) for providing subscriber signals (tsigl, tsig2, .. tsign) for power measurement in a radio communication system, with

- an assigned antenna device (AE) for directional radiation, - a signal processing device (SVE) for superimposing at least two subscriber signals (tsigl, tsig2) spread with individual spreading codes (cl, c2) into a sum signal (sumsig),

- a transmitting device (SE) for transmitting the subscriber signals (tsigl, tsig2), and

- A control device (ST) for controlling the transmission power (E1, E2) of the subscriber signals (tsigl, tsig2) and for controlling a constant transmission power (E) for the sum signal (sumsig) to determine times for performing the power measurement by a radio station (MS ).

10. Base station (BS) according to claim 9, in which the signal processing device (SVE) is designed in such a way that the subscriber signals (tsigl, tsig2) are fitted in blocks into a time slot (tsl) for subscriber separation.

11. Base station according to claim 9 or 10, in which the signal processing device (SVE) assigns a group of subscriber signals (tsigl, tsig2, .. tsign) to the time slots (tsl, ts2, .. ts8) such that the sum of the individual Transmitting powers (El, E2, .. En) in each time slot (tsl, ts2, .. ts8) result in a certain target transmitting power (Esoll).