WO2009072957A1

WO2009072957A1 - Method for use of random access resources

Info

Publication number: WO2009072957A1
Application number: PCT/SE2008/051035
Authority: WO
Inventors: Huaisong Zhu; Jie Mao; Lei Xiao
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2007-12-06
Filing date: 2008-09-16
Publication date: 2009-06-11
Also published as: CN101933380A; CN101933380B

Abstract

The invention discloses methods and arrangements for use of random access resources in a wireless communication system. At a service request from the UE, the base station will assign a random access resource (a SYNC_UL code) to the UE. The UE will send a signal using the assigned resource, upon which the base station will measure signal strength, time of arrival or location of the user equipment. The invention thus solves the problem of inefficient use of spreading factor codes as resources for sending signals intended for measuring.

Description

Method for use of random access resources

TECHNICAL FIELD

The present invention relates to a method and arrangement in a user equipment and to a method and arrangement in a base station. More particularly, the present invention relates to an improved mechanism for initiating a random access procedure to a wireless communication system via the base station.

BACKGROUND Currently, standardized and commercially deployed radio access technologies are proliferated, for use in wireless communications systems. Such radio access technologies include cellular communication systems which operate on the Time Division Duplex (TDD) principle. An example of a cellular wireless communications system operating on TDD is Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems.

In a TD-SCDMA system, as well as in other cellular wireless communication systems, there will be a first transceiver, a so called base station, or in this instance a NodeB, which serves to control the traffic to and from user terminals within a geographical area, a cell, of the system.

The traffic for the user terminals to the NodeB is referred to as uplink traffic, and traffic from the NodeB to the user terminals is referred to as downlink traffic.

The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations, to make a globally applicable third generation mobile phone system specification.

The 3GPP TD-SCDMA standard introduces an uplink synchronization code (SYNC_UL). SYNC_UL codes are used for doing random access and TD-SCDMA allocates a special timeslot called Uplink Pilot Timeslot (UpPTS) with a duration of 125 μs for the SYNCJJL code. A user terminal can randomly select one SYNC_UL code, and send the SYNC_UL code in this timeslot to request access to the network. The 3GPP TD-SCDMA standard defines max 8 SYNC_UL codes which can be allocated for each carrier, which means that simultaneously 8 user terminals can access the radio access network on one carrier. The SYNC_UL code resource is quite large; for example, for a 6 carrier-cell, which may be assumed to be the most commonly used in future networks, there is a total of 8 (SYNC_UL code number in a carrier) ^* 6 (carrier number in a cell), meaning that 48 user terminals can access the network simultaneously in one cell.

4-8 SYNC_UL codes is OK for random access requirement of a cell, so the current TD- SCDMA N-carrier cell standard defines only SYNC_UL codes in the primary carrier, which is used for carrying system broadcasting information, which can be used for random access. SYNC_UL codes are not used in other carriers.

So, 8/48 = 16.7% of SYNC_UL code capacity can be used in a real network according to the current standard.

TDD systems are normally code-limited system for traffic. Thus, if High Speed Downlink Packet Access (HSDPA), sometimes referred to as "Turbo 3G", and/or High-Speed Uplink Packet Access (HSUPA) are introduced into the radio access network, a substantial amount of uplink and/or downlink codes must be allocated for HSDPA/HSUPA. Consequently, the problems associated with code limitation in a TDD based communication system will aggravate.

The above discussed standard defines an Associated Dedicated CHannel (A-DCH, for both HSDPA and HSUPA) or non-schedule resource (for HSUPA only) for each HSDPA/HSUPA service.

One purpose of A-DCH/non-schedule resource is to transmit some service with Guaranteed Bit Rate (GBR) or to keep Quality of Service (QoS) requirements.

Another purpose of A-DCH/non-schedule resource is to keep synchronization, power control and beam forming with the help of A-DCH/non-schedule resource. This means that although there is no data to send, a user terminal must periodically send special bursts, a pre-defined fix sequence with no user terminal data information. Thus 2 spreading factor codes (SF16) must be allocated for this user terminal. To keep synchronization/power control and beam forming is the key to sustaining traffic between a user terminal and the radio access network. As an example, correct beam forming is the key to enlarge the cell capacity and cell range. Consequently A-DCH/non- schedule resource is very important and cannot be replaced by a shared HSDPA/HSUPA resource.

Thus, currently, A-DCH/non-schedule resource is mandatory for HSDPA/HSUPA according to the standard.

Another problem with existing solutions is that HSDPA/HSUPA can improve cell throughput and support a larger number of user terminals, but with the restriction that each user terminal must have A-DCH/non-schedule resource. Thus the cell will still be code limited.

For example if one carrier configures 16 SF16 codes for HSUPA, for which the max throughput limit is about 512 kbps and 48 SF16 codes for HSDPA for which the max throughput is about 1.5 Mbps, it can fully support 7-10 user terminals with Packet Switched (PS) services. With A-DCH requirements however, if also common channel requirements are considered, as they will consume some codes from the left codes, one carrier can support 4-6 user terminals' A-DCH, at the most.

Also, it is to be noticed that some codes must be reserved for user terminals which does not support HSDPA/HSUPA. Those user terminals must use dedicated resources to transmit traffic. So from an A-DCH point of view, at the most 3-4 user terminals can be supported for HSDPA/HSUPA.

On the other hand, user terminals can use SYNC_UL codes to keep synchronization, power control and beam forming. However, SYNC_UL code is not dedicated to any user terminal, so the real-time requirement cannot be fulfilled, and can only be used for random access procedure, thus causing a general degrading of the system performance.

SUMMARY

It is therefore an object of the present invention to obviate at least some of the above disadvantages and provide an improved mechanism for initiating a random access procedure in a wireless communication system. According to a first aspect, the object is achieved by a method in a base station for communicating with first user equipment. The base station and the user equipment are comprised within a wireless communication system. The base station and the user equipment are adapted to exchange wireless signals and to use a code selected from a plurality of codes, in order for the user equipment to initiate a random access procedure. The wireless communication system is adapted to operate according to the Time Division Duplex, TDD, principle. The method comprises receiving a service request from the user equipment. Also, a first code is selected from the plurality of codes and dedicated to the user equipment based on the received service request. Further, the information concerning the dedicated code is sent to the user equipment. A signal based on the dedicated code is then received from the user equipment. Still further, the received signal is measured with respect to at least one of the parameters signal strength, time of arrival and/or location of the user equipment.

According to a second aspect, the object is also achieved by an arrangement in a base station for communicating with a first user equipment. The base station and the user equipment are comprised within a wireless communication system. The base station and the user equipment are adapted to exchange wireless signals and to use a code selected from a plurality of codes, in order for the user equipment to initiate a random access procedure. The wireless communication system is adapted to operate according to the Time Division Duplex, TDD, principle. The arrangement comprises a receiving unit. The receiving unit is adapted to receive a service request from the user equipment. The arrangement also comprises a dedicating unit. The dedicating unit is adapted to dedicate a first code selected from the plurality of codes to the user equipment, based on the received service request. Further, the arrangement comprises a sending unit. The sending unit is adapted to send information concerning the dedicated code to the user equipment. Further yet, the arrangement comprises a receiving unit. The receiving unit is adapted to receive a signal based on the dedicated code from the user equipment. In addition, the arrangement comprises a measuring unit. The measuring unit is adapted to measure the received signal with respect to at least one of the parameters signal strength, time of arrival and/or location of the user equipment.

According to a third aspect, the object is achieved by a method in a user equipment for communicating with a base station. The base station and the user equipment are comprised within a wireless communication system. The base station and the user equipment are adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment to initiate a random access procedure. The wireless communication system is adapted to operate according to the Time Division Duplex, TDD, principle. The method comprises sending a service request to the base station. Thereafter, information concerning a dedicated code from the base station is received. Finally a signal based on the received dedicated code is sent to the base station.

According to a fourth aspect, the object is also achieved by an arrangement in a user equipment for communicating with a base station. The base station and the user equipment are comprised within a wireless communication system. Also, the base station and the user equipment are adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment to initiate a random access procedure. The wireless communication system is adapted to operate according to the Time Division Duplex, TDD principle. The arrangement comprises a sending unit. The sending unit is adapted to send a service request to the base station. The arrangement further comprises a receiving unit. The receiving unit is adapted to receive information concerning a dedicated code from the base station. The sending unit is further adapted to send a signal based on the received dedicated code, to the base station.

By changing the SYNC_UL code usage, instead of a shared code resource which can be used by a user equipment who want to do random access, some SYNC_UL codes are reserved by the radio access network, and will be dedicatedly allocated to the user equipment.

If a particular user equipment only need to do uplink synchronization, beam forming etc; and no /seldom need code to transmit traffic, then the radio access network can dedicatedly allocate one SYNC_UL code to this user equipment, and the particular user equipment can period send self-dominated SYNC_UL code to the radio access network.

Thus, by utilizing un-used SYNC_UL code the limited traffic code is saved. Thereby an improved mechanism for initiating a random access procedure in a wireless communication system is provided. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more in detail in relation to the enclosed drawings, in which:

Figure 1 is a schematic block diagram illustrating a wireless communication system according to some embodiments.

Figure 2 is a schematic block diagram illustrating exemplary components of a base station according to some embodiments.

Figure 3A is a schematic block diagram illustrating exemplary components of a user equipment according to some embodiments.

Figure 3B is a schematic block diagram illustrating a user equipment according to some embodiments where the user equipment is embodied as a cellular telephone.

Figure 4 is an illustration over an embodiment of the present method.

Figure 5 is a combined block- and signalling diagram depicting at least parts of the signalling between the user equipment and the base station according to an embodiment.

Figure 6 is a schematic flow chart illustrating an embodiment of the present method in a base station.

Figure 7 is a schematic block diagram illustrating an arrangement in a base station according to some embodiments.

Figure 8 is a schematic flow chart illustrating an embodiment of the present method in a user equipment.

Figure 9 is a schematic block diagram illustrating an arrangement in a user equipment according to some embodiments. DETAILED DESCRIPTION

The invention is defined as a method and an arrangement in a base station and a method and an arrangement in a user equipment, which may be put into practice in the embodiments described below. This invention may, however, be embodied in many different forms and should not be considered as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It should be understood that there is no intent to limit the present method and arrangement in a base station and method and arrangement in a user equipment, to any of the particular forms disclosed, but on the contrary, the present methods and arrangements are to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the claims.

Still other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

Figure 1 is a schematic block diagram illustrating an exemplary wireless communication system 100, according to some embodiments. The wireless communication system 100 comprises a base station 1 10 defining a cell 120, a first user equipment 130, and a control node 140. The wireless communication system 100 may further, according to some embodiments comprise a second user equipment 132.

The wireless communication system 100 may sometimes be referred to as a wireless cellular communications system.

The base station 110 may also be referred to as e.g. an access point, a Node B, a controlling transceiver, an evolved Node B (eNode B) and/or a base transceiver station, Access Point Base Station, base station router, etc depending e.g. of the radio access technology and terminology used. In the rest of the description, the term "base station" will be used for denoting the base station 1 10, in order to facilitate the comprehension of the present methods and arrangements.

The base station 1 10 serves to control the traffic to and from the first user equipment 130 and/ or the second user equipment 132, within a certain geographic area such as the cell 120 in the wireless communication system 100.

The first user equipment 130 and/ or the second user equipment 132 may be represented by e.g. a wireless communication terminal, a mobile cellular telephone, a user terminal, a

Personal Communications Systems terminal, a Personal Digital Assistant (PDA), a laptop, a computer or any other kind of device capable of managing radio resources may communicate wirelessly with the base station 110 within the wireless communication system 100. A Personal Communication System terminal may combine a cellular radiotelephone with data processing, facsimile and data communications capabilities. A

PDA may comprise a radiotelephone, a pager, an Internet/intranet access device, a web browser, an organizer, calendars and/or a global positioning system (GPS) receiver. The user equipment 130 may be referred to as a "pervasive computing" device. However, in the rest of the description, the term "user equipment" will consistently be used for denoting the user equipment 130, 132 in order to facilitate the comprehension of the present methods and arrangements.

The wireless communication system 100 also comprises a control node 140. The control node 140 may be e.g. a Radio Network Controller (RNC). The Radio Network Controller 140 is a governing element in the wireless communication system 100, responsible for control of base stations e.g. the base station 1 10, which are connected to the Radio Network Controller 140. The Radio Network Controller 140 may carry out radio resource management; some of the mobility management functions and may be the point where encryption may be done before user data is sent to and from the at least one user equipment 130, 132.

The first user equipment 130 may communicate with other user equipments such as e.g. the second user equipment 132, or other devices not shown, via the base station 1 10 comprised within the wireless communication system 100. The traffic from the user equipment 130, 132 to the base station 1 10 is referred to as uplink traffic (UL), and traffic from the base station 1 10 to the user equipment 130, 132 is referred to as downlink traffic (DL), as indicated in Figure 1.

The wireless communication system 100 may comprise one or more networks of any type, including a Local Area Network (LAN); a Wide Area Network (WAN); a Metropolitan Area Network (MAN); a telephone network, such as a Public Switched Telephone Network (PSTN) or a Public Land Mobile Network (PLMN); a satellite network; an intranet, the Internet; or a combination of these or other networks. The PLMN may further comprise a packet-switched sub-network, such as, for example, General Packet Radio Service (GPRS), Cellular Digital Packet Data (CDPD), or Mobile IP network.

The wireless communication system 100 may be based on technologies such as e.g. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Wideband Code Division Multiple Access (WCDMA), CDMA 2000, High Speed Packet Access (HSPA), including Enhanced UpLink (EUL) and High Speed Downlink Packet Data Access (HSDPA), EVDO version of CDMA 2000 etc, just to mention some examples.

However, the present solution may be used with particular advantage in wireless communication systems 100 which operate on the Time Division Duplex (TDD) principle.

The invention may be applied to a wide range of TDD systems, but will in the following be explained with reference to a so called TD-SCDMA system, Time Division Synchronous Code Division Multiple Access.

TD-SCDMA, is a 3G mobile telecommunications standard, being pursued in the People's Republic of China by the Chinese Academy of Telecommunications Technology (CATT).

TD-SCDMA uses TDD, in contrast to the Frequency Division Duplex (FDD) scheme used by e.g. WCDMA. By dynamically adjusting the number of timeslots used for downlink and uplink, the system 100 may more easily accommodate asymmetric traffic with different data rate requirements on downlink and uplink than FDD schemes. Since it does not require paired spectrum for downlink and uplink, spectrum allocation flexibility is also increased. Also, using the same carrier frequency for uplink and downlink means that the channel condition is the same on both directions, and the base station 110 may deduce the downlink channel information from uplink channel estimates, which is helpful to the application of beam forming techniques.

TD-SCDMA also uses TDMA in addition to the CDMA used in WCDMA. This may reduce the number of users in each timeslot, which reduces the implementation complexity of multi-user detection and beam forming schemes.

Further, in TD-SCDMA, uplink signals may be synchronized at the base station 110, achieved by continuous timing adjustments. This may reduce the interference between user equipments 130, 132 of the same timeslot using different codes by improving the orthogonality between the codes, therefore increasing system capacity.

It will be appreciated that the number of components illustrated in Figure 1 is purely exemplary. Other configurations with less, more, or a different arrangement of components may be implemented. Moreover, in some embodiments, one or more components in Figure 1 may perform one or more of the tasks described as being performed by one or more other components in Figure 1. To just mention one example, the functionality of the Radio Network Controller 140 may be distributed to the base station 110 in some embodiments, and vice versa.

Figure 2 illustrates one exemplary implementation of the base station 110. The base station 1 10 may comprise e.g. a transceiver 205, a processing unit 210, a memory 215, an interface 220, a bus 225 and an antenna 230. The control node 140 may also be similarly configured; however, the control node 140 may not comprise the transceiver 205, according to some embodiments.

The transceiver 205 may comprise transceiver circuitry for transmitting and/or receiving symbol sequences using radio frequency signals via one or more antennas 230. The one or more antennas 230 may comprise a single antenna 230 or an antenna array and may comprise directional and/or omni-directional antennas 230.

The processing unit 210 may comprise a processor, microprocessor, or processing logic that may interpret and execute instructions. Further, the processing unit 210 may perform all data processing functions for the base station 1 10. The memory 215 may provide permanent, semi-permanent, or temporary working storage of data and instructions for use by the processing unit 210 in performing device processing functions. Also, the memory 215 may comprise a primary storage memory unit such as a processor register, a cache memory, a Random Access Memory (RAM) or similar. The memory unit 215 may however in some embodiments comprise a secondary memory unit such as a Read Only Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), programmable read-only memory (PROM) or erasable programmable read-only memory (EPROM) or a hard disk drive. The memory unit 215 may however in some embodiments comprise an off-line storage memory unit, a flash memory, a USB memory or a memory card. The memory unit 215 may further in some embodiments comprise a Network- attached storage (NAS) or in fact any other appropriate medium such as and/or optical recording medium and its corresponding drive, or any other disk, tape or media that can hold machine readable data.

The interface 220 may comprise circuitry for interfacing with a link that connects e.g. to the base station 110. The bus 225 may interconnect the various components 205, 210, 215, 220, 230 of the base station 1 10 to permit the components to communicate with one another.

The configuration of components of the base station 1 10 illustrated in Figure 2 is for illustrative purposes only. Other configurations with less, more, or a different arrangement of components may be implemented.

Figure 3A illustrates the user equipments 130, 132 consistent with an exemplary embodiment. The user equipment 130, 132 may comprise a transceiver 305, a processing unit 310, a memory 315, an input device 320, an output device 325, and a bus 330.

The transceiver 305 may comprise transceiver circuitry for transmitting and/or receiving symbol sequences using radio frequency signals via one or more antennas.

The processing unit 310 may comprise a Central Processing Unit (CPU), processor, microprocessor, or processing logic that may interpret and execute instructions. The processing unit 310 may perform all data processing functions for inputting, outputting, and processing of data, comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

The memory 315 may provide permanent, semi-permanent, or temporary working storage of data and instructions for use by the processing unit 310 in performing device processing functions. The memory 315 may comprise ROM, RAM, large-capacity storage devices, such as a magnetic and/or optical recording medium and its corresponding drive, and/or other types of memory units. The input device 320 may comprise mechanisms for entry of data into the user equipment 130, 132. The key pad may permit manual user entry of data into the user equipment 130, 132. The microphone may comprise mechanisms for converting auditory input into electrical signals. The display unit may comprise a screen display that may provide a user interface, e.g., a graphical user interface that can be used by a user for selecting device functions. The screen display of the display unit may comprise any type of visual display, such as, for example, a Liquid Crystal Display (LCD), a plasma screen display, a Light-Emitting Diode (LED) display, a Cathode Ray Tube (CRT) display, an Organic Light-Emitting Diode (OLED) display, etc.

The output device 325 may comprise mechanisms for outputting data in audio, video and/or hard copy format. For example, the output device 325 may comprise a speaker (not shown) that includes mechanisms for converting electrical signals into auditory output. The output device 325 may further comprise a display unit that displays output data to the user. For example, the display unit may provide a graphical user interface that displays output data to the user. The bus 330 may interconnect the various components of the user equipment 130, 132 to permit the components to communicate with one another.

The configuration of components of the user equipment 130, 132 illustrated in Figure 3A is for illustrative purposes only. Other configurations with more, fewer, or a different arrangement of components may be implemented. For example, in some implementations, the user equipment 130, 132 may comprise, or be connected to, a Global Positioning System (GPS) position measuring device.

Figure 3B illustrates an exemplary implementation of the user equipment 130, 132 in which the user equipment 130, 132 comprises a cellular radiotelephone. As shown in Figure 3B, the user equipment 130, 132 may comprise a microphone 335, e.g., of input device 320 for entering audio information into the user equipment 130, 132, a speaker 340, e.g., of output device 325 for providing an audio output from the radiotelephone, a keypad 345, e.g., of input device 320 for manual entry of data or selection of telephone functions, and a display 350, e.g., of input device 320 or output device 325 that may 5 visually display data to the user and/or which may provide a user interface that the user may use to enter data or to select telephone functions, in conjunction with keypad 345.

Some signalling and processing steps according to some embodiments of the present solution will now be explained.

10

Just as Discontinuous Transmission (DTX) techniques may be used in TD-SCDMA, transmissions to keep synchronization, beam forming etc do not with necessity need to be scheduled and transmitted every frame. To mention just one non limiting example, a 40 ms interval in between may be OK. Then radio access system can use one SYNC_UL

15 code to support eight user equipments 130, 132. The synchronization between each user equipment 130, 132 with the same SYNC_UL code may be done by signalling controlled by the radio access network.

An example of a detailed procedure, according to some embodiments, may be as follows: 20 In system information, the radio access network may broadcast SYNC_UL code for random access. Thus the radio network may decide how many and which SYNC_UL code can be used in a cell 120.

The Radio network may consider the radio resource consumption; whether a user 25 equipment's 130 traffic can be carried on HSUPA/HSDPA. The radio access network may then allocate a dedicated SYNC_UL code to that user equipment 130 through the signalling instead of allocation of dedicated traffic codes.

If a SYNC_UL code is dedicated to a certain user equipment 130, and the user equipment 30 130 sends this SYNC_UL code to its base station 110, the base station 110 may only use this SYNC_UL code to do beam forming etc, and not perform any random access procedure, such as sending Fast Physical Access Channel (FPACH) and/or receiving on Physical Random Access Channel (PRACH) etc. If current radio resource consumption result in that the user equipment's 130 traffic cannot be carried on HSUPA/HSDPA any more, then A-DCH may be allocated to this user equipment 130, and the dedicated SYNC_UL code may be released from the user equipment 130, according to some embodiments.

For user equipments 130, 132 which do not support the present methods, the radio network 100 may still allocate A-DCH to such user equipments 130, 132, as per current standards.

Periodically sending SYNC_UL code to the radio access network may be OK for the user equipment 130 and the base station 110 to keep uplink synchronization, beam forming, and power control. The Radio access network can select making user equipment 130 sending SYNC_UL code continuously or discontinuously with consideration of whether SYNC_UL code resource is sufficient or not.

Figure 4 illustrates how discontinuous sending of SYNC_UL, sending per 20ms in the example, can make one SYNC_UL code shared by four user equipments 130, 132, UE 1 - 4. SYNC_UL code 5 is used as a non limiting example only.

Thus each user equipment 130, 132, UE1-4, may use the SYNC_UL code 5 to do uplink synchronisation and beam forming for 5 ms, repeatedly every 20 ms, as illustrated in Figure 4.

Figure 5 illustrates some signalling and processing steps according to some embodiments of the present solution. It is thus illustrated in Figure 5 how the SYNC_UL codes may be reused in the TD-SCDMA system, according to some embodiments.

In order to further facilitate the reader's understanding of the present methods and arrangements, another example will now be given.

510

When the user equipment 130 wants to establish some service, for example File Transfer Protocol (FTP), then the user equipment 130 may tell the base station 1 10 what kind of service the user equipment 130 wants to use. For example, what maximum bit rate is set for this user equipment applied service. This user equipment information may be transmitted to the base station 1 10 through standard signalling.

520

5 When the base station 110 knows what the user equipment 130 wants, the base station 110 may decide several parameters, such as e.g. whether to allocate or not allocate resources for the particular user equipment 130 and how to allocate the resources for this user equipment 130. For example, for a requested packet service from the user equipment 130, the base station 1 10 may allocate this service on a common channel, 10 such as HSDPA/HSUPA; or allocate this service on a dedicated channel. Further, other physical resources may be allocated to this user equipment 130, such as timeslot, code, Transmission power etc.

Several algorithms may be introduced and used, such as Dynamic Channel Allocation 15 (DCA) and Admission Control (AC) etc.

The base station 1 10 may inform the user equipment 130 concerning which allocated resources to use by sending a message to the user equipment 130.

20 530

The user equipment 130 may use the allocated resources and initiate a session according to the requested service.

540

25 Optionally, the base station 1 10 may detect that congestion occurs, or that the user equipment 130 does not fully use the allocated resources etc. The base station 110/or RNC 140 may then adjust its allocation decision automatically. For example, all resource may be occupied by user equipment 130 with packet services; then, a voice call may be requested by a second user equipment 132. In such a scenario, the base station 1 10 may

30 attempt to release some resource from packet service, which is with low priority, to support voice service, which is with high priority. Several algorithms may be introduced, such as e.g. congestion control and Channel switching. Thus, in an example with ten user equipments 130, 132 in the cell 120, and the base station 110/or RNC 140 decides to allocate dedicated SYNC_UL codes to five of those user equipments 130, 132, this may be done e.g. in the manner described above.

For example, in step 520 above, a user equipment 130 may request an Uplink max bit rate 64 Kbits per second, and a downlink max bit rate 512 Kbits per second. The base station 110/or RNC 140 may then decide how to allocate resource to this user equipment 130. For example, the base station 1 10 may be configured so that packet service may be in high priority to be allocated in HSDPA/HSUPA. Then the base station 1 10/or RNC 140 may check the current HSDPA/HSUPA resource consumption condition. If free resource is OK for this new service, then the base station 110/or RNC 140 may allocate this user equipment 130 to HSDPA/HSUPA. Further, the base station 110/or RNC 140 may also check SYNC_UL resources. If still free resource is OK, the base station 1 10 /or RNC 140 may allocate SYNC_UL to this user equipment 130. Then all these allocation results may be informed to user equipment 130 through standard defined signalling.

Similarly to step 540, for example, if SYNC_UL code is not enough for the first user equipment 130 when a call is setup; then the first user equipment 130 may be allocated with a dedicated channel instead of SYNC_UL code; but when some other user equipment 132 releases a call, then a SYNC_UL code is released. The base station 1 10 /or RNC 140 may then reallocate the SYNC_UL code to the first user equipment 130, and release dedicated channel of the first user equipment 130 to save resources, according to some embodiments.

Figure 6 is a flow chart illustrating a method in the base station 110 for communicating with a first user equipment 130. The base station 110 and the user equipment 130 are comprised within a wireless communication system 100 and adapted to exchange wireless signals. Further, the base station 110 and the user equipment 130 are configured to use a code selected from a plurality of codes, in order for the user equipment 130 to initiate a random access procedure. The wireless communication system 100 is adapted to operate according to the Time Division Duplex, TDD, principle.

To appropriately communicate with the first user equipment 130, the method may comprise a number of steps 601-609. It is however to be noted that some parts of the described method steps are optional and only comprised within some embodiments. Further, it is to be noted that the method steps 601-609 may be performed in any arbitrary chronological order and that some of them, e.g. step 602 and step 603, or even all steps may be performed simultaneously or in an altered, arbitrarily rearranged, decomposed or even completely reversed chronological order. The method comprises the following steps:

Step 601

A service request is received from the user equipment 130.

Step 602 A first code is selected from the plurality of codes and is dedicated to the user equipment 130, based on the received service request.

Step 603

Information concerning the dedicated code is sent to the user equipment 130.

Step 604

A signal based on the dedicated code from the user equipment 130 is received.

Step 605 The received signal is measured with respect to at least one of the parameters signal strength, time of arrival and/or location of the user equipment 130.

Step 606

This method step is optional and only performed within some embodiments.

The at least one antenna 230 of the base station 110 may be beam formed, based on the location of the user equipment 130 when transmitting signals to/from the user equipment 130, according to some embodiments.

Step 607

This method step is optional and only performed within some embodiments.

An adjustment command for adjusting the transmission power of signals sent from the user equipment 130 may be sent, based on the measured signal strength. Step 608

This method step is optional and only performed within some embodiments.

The signal transmission of the user equipment 130 may, according to some embodiments be synchronized with the signal transmission of other user equipments, based on the measured time of arrival.

Step 609 This method step is optional and only performed within some embodiments.

The same code may be dedicated to a second user equipment 132, which code has previously been dedicated to the first user equipment 130.

To perform the method steps above, the base station 110 comprises an arrangement 700, depicted in Figure 7. The arrangement 700 is configured for communicating with a first user equipment 130. The base station 110 and the user equipment 130 are comprised within a wireless communication system 100. Further, the base station 110 and the user equipment 130 are adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment 130 to initiate a random access procedure. The wireless communication system 100 is adapted to operate according to the Time Division Duplex, TDD, principle.

The arrangement 700 comprises a receiving unit 710. The receiving unit 710 is adapted to receive a service request from the user equipment 130. Further, the arrangement 700 comprises a dedicating unit 720. The dedicating unit 720 is adapted to dedicate a first code selected from the plurality of codes to the user equipment 130, based on the received service request. Also, the arrangement 700 comprises a sending unit 730. The sending unit 730 is adapted to send information concerning the dedicated code to the user equipment 130. Additionally, the arrangement 700 comprises a measuring unit 740. The measuring unit 740 is adapted to measure the received signal with respect to at least one of the parameters signal strength, time of arrival and/or location of the user equipment 130. According to some optional embodiments, the arrangement 700 further may comprise a beam forming unit 760. The beam forming unit 760 may be adapted to beam form at least one antenna 230 of the base station 110 based on the location of the user equipment 130 when transmitting signals to/from the user equipment 130.

Also, according to some optional embodiments, the arrangement may comprise a synchronization unit 780. The synchronization unit 780 may be adapted to synchronise the signal transmission of the user equipment 130 with the signal transmission of other user equipments, based on the measured time of arrival.

It is to be noted that any internal electronics of the base station 110 not completely necessary for performing the present method according to the method steps 601-609, such as e.g. some of the internal electronics of the base station depicted in Figure 2 has been omitted from Figure 7, for clarity reasons.

It is further to be noted that the described units 710-780 comprised within the arrangement 700 in the base station 110 are to be regarded as separate logical entities but not with necessity separate physical entities. Any, some or all of the units 710-780 may be comprised or co-arranged within the same physical unit. However, in order to facilitate the understanding of the functionality of the arrangement 700 in the base station 110, the comprised units 710-780 are illustrated as separate physical units in Figure 7.

Thus the receiving unit 710 and e.g. the sending unit 730 may, according to some embodiments, be comprised within one physical unit, a transceiver, which may comprise a transmitter circuit and a receiver circuit, which respectively transmits outgoing radio frequency signals to the user equipment 130 and receives incoming radio frequency signals from the user equipment 130 via an antenna. The antenna may be an embedded antenna, a retractable antenna or any antenna known to those having skill in the art without departing from the scope of the present invention. The radio frequency signals transmitted between the user equipment 130 and the base station 1 10 may comprise both traffic and control signals e.g., paging signals/messages for incoming calls, which may be used to establish and maintain a voice call communication with another party or to transmit and/or receive data, such as SMS, e-mail or MMS messages, with another remote user equipment 130. Figure 8 is a flow chart illustrating a method in the user equipment 130, for communicating with a base station 110. The base station 110 and the user equipment 130 are comprised within a wireless communication system 100. The base station 110 and the user equipment 130 are adapted to exchange wireless signals. Further, the base station 5 110 and the user equipment 130 are adapted to use a code selected from a plurality of codes in order for the user equipment 130 to initiate a random access procedure. The wireless communication system 100 is adapted to operate according to the Time Division Duplex, TDD, principle. 0 To appropriately communicate with the base station 110, the method may comprise a number of steps 801-804. It is however to be noted that some parts of the described method steps are optional and only comprised within some embodiments. Further, it is to be noted that the method steps 801-804 may be performed in any arbitrary chronological order and that some of them, e.g. step 801 and step 802, or even all steps may be5 performed simultaneously or in an altered, arbitrarily rearranged, decomposed or even completely reversed chronological order. The method comprises the following steps:

Step 801

A service request is sent to the base station 110. 0

Step 802

Information concerning a dedicated code is received from the base station 110.

Step 803 5 A signal based on the received dedicated code is sent to the base station 110. According to some optional embodiments, the signal may be sent to the base station 110 with a certain periodicity.

Step 804 0 This method step is optional and may only be performed within some embodiments. An adjustment command for adjusting the transmission power of signals sent to the base station 110 may be received.

To perform the method steps above, the first user equipment 130 comprises an5 arrangement 900, depicted in Figure 9. The arrangement 900 is configured for communicating with a base station 110. The base station 110 and the user equipment 130 are comprised within a wireless communication system 100. Further, the base station 110 and the user equipment 130 are adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment 130 to initiate a random access procedure. The wireless communication system 100 is adapted to operate according to the Time Division Duplex, TDD principle.

The arrangement 900 comprises a sending unit 910. The sending unit 910 is adapted to send a service request to the base station 110. The arrangement 900 also comprises a receiving unit 920. The receiving unit 920 is adapted to receive information concerning a dedicated code from the base station 110. The sending unit 910 is further adapted to send a signal based on the received dedicated code, to the base station 110. According to some optional embodiments, the sending unit 910 may be adapted to send the signal to the base station 110 with a certain periodicity. The receiving unit 920 may according to some embodiments be further adapted to receive an adjustment command for adjusting the transmission power of signals sent to the base station 110.

It is to be noted that any internal electronics of the user equipment 130 not completely necessary for performing the present method according to the method steps 801-804, such as e.g. some of the internal electronics of the user equipment depicted in Figure 3A and 3B, has been omitted from Figure 9, for clarity reasons.

A calculating unit 930 may be comprised within the arrangement 900 in the user equipment 130. The optional calculating unit 930 may be e.g. a processing unit, a CPU or any logic machine with ability to execute a computer program.

It is to be noted that the described units 910-930 comprised within the arrangement 900 in the user equipment 130 are to be regarded as separate logical entities but not with necessity separate physical entities. Any, some or all of the units 910-930 may be comprised or co-arranged within the same physical unit. However, in order to facilitate the understanding of the functionality of the arrangement 900 in the user equipment 130, the comprised units 910-930 are illustrated as separate physical units in Figure 9.

Thus the sending unit 910 and e.g. the receiving unit 920 may, according to some embodiments, be comprised within one physical unit, a transceiver, which may comprise a transmitter circuit and a receiver circuit, which respectively transmits outgoing radio frequency signals to the base station 110 and receives incoming radio frequency signals from the base station 1 10 via an antenna. The antenna may be an embedded antenna, a retractable antenna or any antenna known to those having skill in the art without departing from the scope of the present invention. The radio frequency signals transmitted between the user equipment 130 and the base station 1 10 may comprise both traffic and control signals e.g. paging signals/messages for incoming calls, which may be used to establish and maintain a voice call communication with another party or to transmit and/or receive data, such as SMS, e-mail or MMS messages, with another, remote, user equipment which is different from the first user equipment 130.

Some particular embodiments

The present methods for communication may be implemented through one or more processors in the base station 110 and/or the user equipment 130, together with computer program code for performing the functions of the present methods. The program code mentioned above may be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the methods according to the respective method steps when being loaded into the processor units comprised within the base station 110 and/or the user equipment 130, respectively. The data carrier may be e.g. a CD ROM disc, a memory stick, or any other appropriate medium such as a disk or tape that can hold machine readable data. The computer program code may furthermore be provided as pure program code on a server and downloaded to the base station 110 and/or the user equipment 130 remotely.

A computer readable medium encoded with a computer program for communication may perform the method according to at least some of the described method steps 601-609, when loaded into the base station 110. Thus a computer program comprising instruction sets for performing the method according to at least some of the method steps 601-609 may be used for implementing the previously described method.

Further, a computer readable medium encoded with a computer program for communication may perform the method according to at least some of the described method steps 801-804, when loaded into the user equipment 130. Thus a computer program comprising instruction sets for performing the method according to at least some of the method steps 801-804 may be used for implementing the previously described method.

The invention is not limited to the examples of embodiments described above and shown in 5 the drawings, but may be freely varied within the scope of the appended claims. Thus, the invention may be applied to other TDD systems than the TD-SCDMA system, which system has been used in the description above and in the drawings in order to facilitate the reader's understanding of the present invention.

10 Yet some particular embodiments

According to some particular embodiments, a method for use in a cellular communications Time Division Duplex system 100, a TDD-system, is provided. The TDD-system 100 may comprise at least one Radio Base Station 110 which serves to control traffic to and from user equipments 130, 132, in a cell 120 in the system 100, in which system 100 user equipments

15 130, 132 can use one of a first plurality of codes in order to initiate a random access procedure to the system 100 via the Radio Base Station 110. The method is characterized in that a first sub-set of said plurality of codes is dedicated to a first number of user equipments 130, 132 which fulfil certain criteria regarding their transmissions to and/or from the Radio Base Station 110. Thus said first number of user equipments 130, 132 can use said first sub-

20 set of codes for transmissions to the Radio Base Station 110. Further, the Radio Base Station 110 can use those transmissions for at least one of the following purposes: measurements on uplink signals, for locating user equipments 130, 132, measurements of uplink signal strength and/or measurement of uplink signal arrive times.

25 According to some optional embodiments, the location of the user equipments 130, 132 may be used for beam forming transmission towards the user equipments 130, 132.

According to some optional embodiments, the measurements of uplink signal strength may be used for power control of transmissions to the user equipments 130, 132. Further, the 30 measurements of uplink signal arrive times may be used for synchronization between the Radio Base Station 110 and the user equipment 130, according to some embodiments.

According to some embodiments, said first number of user equipments 130, 132 may make transmissions with the dedicated codes with a certain periodicity.

35 According to yet some optional embodiments, a group of user equipments 130, 132 may have one and the same code dedicated to them, and the user equipments 130, 132 may use this code in a manner which is controlled by the system 100.

According to some optional embodiments, said certain criteria may include the fact that the first number of user equipments 130, 132 use an up and/or down link payload traffic method which does not enable the Radio Base Station 110 to carry out one of the following: beam forming transmission towards the user equipments 130, 132, Power control of transmissions to the user equipment 130, 132 and/or Synchronization between the Radio Base Station 110 and the user equipment 130, 132.

The up and/or down link payload traffic methods may, according to some embodiments, include High Speed Down Link Packet Access and HSUPA, High Speed Up Link Packet Access.

The terminology used in the detailed description of the particular exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms "includes," "comprises," "including" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or

"coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Claims

1. Method in a base station (110), for communicating with a first user equipment (130), the base station (110) and the user equipment (130) are comprised within a wireless communication system (100) and adapted to exchange wireless signals and to use a code selected from a plurality of codes, in order for the user equipment (130) to initiate a random access procedure, the wireless communication system (100) is adapted to operate according to the Time Division Duplex "TDD" principle, the method comprises the steps of: receiving (601 ) a service request from the user equipment (130), dedicating (602) a first code selected from the plurality of codes to the user equipment (130), based on the received service request, sending (603) information concerning the dedicated code to the user equipment (130), receiving (604) a signal based on the dedicated code from the user equipment (130), and measuring (605) the received signal with respect to at least one of the parameters signal strength, time of arrival and/or location of the user equipment (130).

2. Method according to claim 1 , wherein the base station (110) further comprises at least one antenna (230) and the method comprises the further step of: beam forming (606) the at least one antenna (230) of the base station (110) based on the location of the user equipment (130) when transmitting signals to, or receiving signals from, the user equipment (130).

3. Method according to claim 1 or 2, further comprising the step of: sending (607) an adjustment command for adjusting the transmission power of signals sent from the user equipment (130) based on the measured signal strength.

4. Method according to any of the previous claims 1-3, further comprising the step of: synchronizing (608) the signal transmission of the user equipment (130) with the signal transmission of other user equipments, based on the measured time of arrival.

5. Method according to any of the previous claims 1-4, wherein the step of receiving (604) a signal is performed with a certain periodicity.

6. Method according to any of the previous claims 1-5, further comprising the step of: dedicating (609) the same code to a second user equipment (132), which code has previously been dedicated to the first user equipment (130).

7. Method according to any of the previous claims 1-6, wherein the step of dedicating (602) a first code selected from the plurality of codes to the first user equipment (130), based on the received service request, is performed if the service request received from the user equipment (130) concerns an up and/or down link payload traffic method which does not enable the base station (110) to perform any of: beam forming transmission towards the user equipment (130), power control of transmissions to the user equipment (130) or synchronization between the base station (110) and the user equipment (130).

8. Method according to claim 7, wherein the up and/or down link payload traffic method comprises either High Speed Down Link Packet Access "HSDPA", or High Speed Up Link Packet Access "HSUPA".

9. Arrangement (700) in a base station (110), for communicating with a first user equipment (130), the base station (110) and the user equipment (130) are comprised within a wireless communication system (100) and adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment (130) to initiate a random access procedure, the wireless communication system (100) is adapted to operate according to the Time Division Duplex "TDD" principle, the arrangement (700) comprises: a receiving unit (710), adapted to receive a service request from the user equipment (130), a dedicating unit (720) adapted to dedicate a first code selected from the plurality of codes to the user equipment (130), based on the received service request, a sending unit (730) adapted to send information concerning the dedicated code to the user equipment (130), a receiving unit (740) adapted to receive a signal based on the dedicated code from the user equipment (130), and a measuring unit (750) adapted to measure the received signal with respect to at least one of the parameters signal strength, time of arrival and/or location of the user equipment (130).

10. Method in a first user equipment (130), for communicating with a base station (110), the base station (110) and the first user equipment (130) are comprised within a wireless communication system (100) and adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment (130) to initiate a random access procedure, the wireless communication system (100) is adapted to operate according to the Time Division Duplex "TDD" principle, the method comprises the steps of: sending (801 ) a service request to the base station (110), receiving (802) information concerning a dedicated code from the base station (110), sending (803) a signal based on the received dedicated code to the base station (110).

11. Method according to claim 10, further comprising the step of: receiving (804) an adjustment command for adjusting the transmission power of signals sent to the base station (110).

12. Method according to any of the previous claims 10 or 11 , wherein the step of sending (803) a signal to the base station (110) is performed with a certain periodicity.

13. Arrangement (900) in a first user equipment (130), for communicating with a base station (110), the base station (110) and the user equipment (130) are comprised within a wireless communication system (100) and adapted to exchange wireless signals and to use a code selected from a plurality of codes in order for the user equipment (130) to initiate a random access procedure, the wireless communication system (100) is adapted to operate according to the Time Division Duplex "TDD" principle, the arrangement (900) comprises: a sending unit (910), adapted to send a service request to the base station (110), a receiving unit (920), adapted to receive information concerning a dedicated code from the base station (110), and wherein the sending unit (910) is further adapted to send a signal based on the received dedicated code, to the base station (110).