HK1202013B - Methods and devices for random access power control in a communications network - Google Patents

Description

Method and apparatus for random access power control in a communication network

Technical Field

The present invention relates to methods and apparatus in a communication network, and more particularly, to methods and apparatus for designing random access transmission power settings for a communication device.

Background Art

In modern cellular radio systems, the radio network has strict control over the behavior of user equipment (UE). Uplink transmission parameters such as frequency, timing and power are regulated via downlink (DL) control signaling from the base station to the UE.

At power-up or after a long standby time, the UE is not synchronized in the uplink. Therefore, the first step to access the network is to obtain synchronization to the network. This is usually done by the UE by listening to the downlink signal and obtaining downlink timing synchronization, frequency error estimation and DL path loss estimation from such signal. Even if the UE is time synchronized to the DL at this time, the signal transmitted by the UE is still not aligned with the expected reception timing at the base station due to the unknown round trip timing. Therefore, before starting traffic, the UE must perform a random access (RA) procedure to the network. After the RA, the eNodeB can estimate the timing misalignment of the UE uplink and send a correction message. The random access procedure can also be used by a synchronized UE in the absence of a valid uplink allocation for data transmission in order to request such an allocation.

A physical random access channel (PRACH) is typically provided for UEs to request access to the network. Access bursts are used, which contain a preamble with a specific sequence with good autocorrelation properties. The PRACH can be orthogonal to traffic channels. For example, in GSM, special PRACH time slots are defined. Since multiple UEs can request access simultaneously, collisions can occur between requesting UEs. Therefore, LTE defines multiple RA preambles. A UE performing RA randomly selects a preamble from a pool and transmits it. The preamble represents a random UE ID, which is used by the eNodeB when granting a UE access to the network.

The eNodeB receiver can resolve RA attempts performed using different preambles and send a response message to each UE using the corresponding random UE ID. If multiple UEs use the same preamble simultaneously, a collision occurs and the RA attempt is likely to be unsuccessful because the eNodeB cannot distinguish between two users with the same random UE ID. In LTE, 64 preambles are provided in each cell. The preambles assigned to adjacent cells are usually different to ensure that RA in one cell does not trigger any RA events in adjacent cells. Therefore, the information that must be broadcast is the set of preambles that can be used for RA in the current cell.

The power used by the UE to transmit the RA preamble is typically calculated via open-loop power control. The UE measures the power of some downlink signal with known transmit power, such as a reference signal or synchronization signal, and calculates the DL path loss. The power of the signal used to estimate the path must be known, so this information must be signaled to the UE via broadcast at initial access or possibly dedicated signaling during handover.

The path loss is calculated as:

PL＝P _RS，RX -P _RS，TX

Wherein, P _RS,RX and P _RS,TX are the received and transmitted powers of the signal used for path loss estimation, respectively, in dBm.

To maintain a certain quality standard for RA reception, a minimum signal-to-noise (or interference) ratio is required at the base station. The base station knows the current interference conditions and can therefore calculate the minimum required signal power P _0,RACH that the RA signal must have at the base station to meet the required quality standard. This power level is also signaled to the UE. Using this power level together with the previously calculated path loss, the UE now calculates:

P _RACH =min{P _{0, RACH} -PL+(N-1)Δ _RACH , P _max }

This is the transmit power required to achieve power level P0 _,RACH at the base station. This means that the path loss—which is already calculated in the DL—is the same for the UL, which is typically not the case for FDD systems. Therefore, open-loop power control is a rather crude mechanism. To overcome this limitation, very frequent power ramping is applied. Here, each subsequent attempt is performed with a transmit power increased by _ΔRACH . In the above formula, this is reflected by the term (N-1)· _ΔRACH , where N is the number of transmission attempts.

The interference level at the eNodeB and hence the required target received power P0 _,RACH depends on many factors and can vary over a wide range. Typically, P0 _,RACH is encoded and transmitted using a fairly low number of bits, such as 4 bits, and spans a range of approximately 30 dB.

LTE systems are expected to be deployed in a wide range of scenarios, from picocells to very large cells up to 100 km and beyond. Since RA is the first procedure performed by a UE to access the network, it is crucial that random access works in all expected scenarios. If RA fails, the UE cannot access the network.

To ensure satisfactory RA performance, the LTE standard defines multiple preamble formats. For FDD mode, four preambles are defined, and TDD mode even specifies an additional fifth preamble. Some of these preambles are designed for larger cells and are therefore longer than others. The received power, and therefore the performance of the random access procedure, is affected by the RA configuration.

Summary of the Invention

One object of embodiments herein is to implement an efficient random access procedure.

Embodiments relate to a method in a first communication device within a communication network for designing a random access transmit power setting of the first communication device.

A first communication device receives data indicating a random access receive power from a second communication device over a radio channel. The first communication device then determines an expected random access receive power for the second communication device based on the received data and a random access configuration parameter that affects random access detection performance at the second communication device. Furthermore, the first communication device determines a random access transmit power to be used based on the expected random access receive power, and designs a random access transmit power setting for the first communication device according to the determined random access transmit power to be used.

To perform the method, a first communication device is provided. The first communication device includes a receiving arrangement configured to receive data indicating a random access receive power from a second communication device over a radio channel to detect a random access transmission. The first communication device also includes a control unit configured to determine an expected random access receive power of the second communication device based on the received data and a random access configuration parameter that affects random access detection performance at the second communication device. The control unit is further configured to determine a random access transmit power design setting based on the expected random access receive power.

In some embodiments, a method in a second communication device within a communication network for transmitting data over a radio channel is provided.

The second communication device determines an expected random access received power from the first communication device, enabling the second communication device to detect a random access request from the first communication device using a random access configuration parameter. The second communication device then determines data based on the expected random access received power and the random access configuration parameter, and transmits the data to the first communication device via a radio channel.

To perform the method, a second communication device is provided. The second communication device includes a control unit configured to determine an expected random access received power from the first communication device, enabling the second communication device to detect a random access request from the first communication device. The control unit is further configured to determine data based on the expected random access received power and a random access configuration parameter. The second communication device also includes a transmission arrangement configured to transmit the data to the first communication device via a radio channel.

Embodiments are directed to methods and apparatus in which the power setting of a transmission takes into account the preamble format and the subsequent random access procedure will be more efficient.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described in more detail with respect to the accompanying drawings, in which:

FIG1 shows a schematic overview of a communication device in a communication network,

FIG2 shows the missed detection performance of the signal-to-noise ratio for the five preamble formats defined in LTE.

FIG3 shows a schematic combination method and signaling scheme,

FIG4 shows a schematic flow chart of a method in a first communication device,

FIG5 shows a schematic diagram of a first communication device,

FIG6 shows a schematic flow chart of a method in a second communication device, and

FIG7 shows a schematic overview of a second communication device.

DETAILED DESCRIPTION

Embodiments of the present invention are described more fully below with reference to the accompanying drawings, which illustrate embodiments of the present invention. However, the present invention may be embodied in many different forms and should not be considered 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. Like reference numerals represent like elements throughout.

The terms used herein are for describing specific embodiments only and are not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is also to be understood that the terms "include" and/or "comprising" when used herein indicate the presence of the recited 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.

Unless otherwise defined, all terms (including technical terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It is also understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art, and will not be understood in an idealized or overly formal sense unless explicitly defined herein.

The present invention is described below with reference to block diagrams and/or flowchart illustrations of methods, devices (systems) and/or computer program products according to embodiments of the present invention. It is to be understood that the blocks of the block diagrams and/or flowchart illustrations and the combination of blocks in the block diagrams and/or flowchart illustrations can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer and/or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer and/or other programmable data processing device create components for implementing the functions/actions specified in the block diagrams and/or flowchart illustrations.

The present invention is described herein as being used in and in conjunction with a communication device, also denoted as a mobile device. In the context of the present invention, a mobile device may be, for example, a mobile phone, a PDA (Personal Digital Assistant), a base station or any other type of portable computer, for example a laptop computer.

The communication network may be, for example, a cellular mobile communication network, such as a GPRS network, a third generation WCDMA network, LTE, etc. Given the rapid development of communications, there are of course future types of wireless communication networks that may be used to embody the present invention.

The communication apparatus includes user equipment, base stations, controller nodes, combinations thereof, and the like.

The control unit may comprise a single processing unit or a plurality of processing units. Similarly, the memory unit may comprise a single or a plurality of memory units, such as internal and/or external memories.

In Figure 1, a schematic overview of a communication device 10, such as a UE, is shown in a communication network 1. Upon power-up or after a long standby period, the UE 10 is not synchronized in the uplink 4 to the base station 20. Therefore, the first step in accessing the network is to obtain synchronization with the network 1. This is typically done by the UE 10 listening to signaling on the downlink 3 and deriving downlink timing synchronization, frequency error estimates, and DL path loss estimates from such signals.

The base station 20 signals an indication of the expected random access reception power to the UE 10 so that the base station 20 can detect the random access request from the UE 10 .

The UE 10 determines a random access transmission power to be used according to the determined expected random access reception power of the second communication device. The expected random access reception power is based on the received indication and a random access configuration parameter that affects random access detection performance at the second communication device.

For example, the random access configuration parameter that affects the random access detection performance at the second communication device may be the preamble format. With a longer preamble, the eNodeB receiver can accumulate the received signal power for a longer time and thus operate at a lower signal-to-noise ratio than required with a shorter preamble.

On the other hand, the additional fifth preamble in TDD mode is very short and therefore requires a higher signal-to-noise ratio.

Even if existing solutions allow P0 _,RACH to be selected from an interval approximately 30 dB wide, the useful interval for a particular preamble is still low. For example, short TDD preambles will not work with P0 _,RACH values from the lower end of the interval, while long preambles generally do not require the highest P0 _,RACH values.

Different RA configurations require different signal powers at the eNodeB receiver to achieve the same detection performance, and embodiments calibrate the transmit power to account for these different levels. This means that the range of values for the required receive power is better adapted to the individual preamble formats/basic cyclic shift values, etc., than without calibration. The cyclic shift value is a parameter used to derive the cyclic shift unit in the root sequence, and subgroups can be sorted by cyclic shift value.

Figure 2 shows the missed detection performance of the signal-to-noise ratio for the five preamble formats defined in LTE. Preamble formats 0 and 1 are shown by curves L0 and L1. Preamble formats 2 and 3 are shown by curves L2 and L3, and short preamble format 4 is shown by curve L4. It can be seen that preamble format 3 requires a signal-to-noise ratio that is 9 dB lower than that of preamble format 4 to achieve a missed detection rate of 1e-3.

It is recommended to add a preamble format dependent correction term to the formula describing the required transmit power. This shifts the expected receive power range up or down to a power interval more appropriate for the preamble used.

Since the preamble format is signaled to the UE anyway, the UE knows which preamble to use and thus also the preamble-related offset. This offset can be 0 for preamble formats 0 and 1 (normal long), negative for preamble formats 2 and 3 (long preamble), and positive for preamble format 4 (very short preamble).

Another explanation is that the bit pattern signaling P _0,RACH is interpreted differently according to the preamble format.

Another possibility is to use different offsets for different P _RACH transmission purposes. For example, a (time critical) P _RACH transmission in the target cell after handover may use a positive offset compared to other P _RACH transmissions.

Formula for calculating RA transmit power

P _RACH =min{P _{0, RACH} -PL+(N-1)Δ _RACH , P _max }

This is then modified by an offset that depends on the preamble format:

P _RACH =min{P _{0, RACH} -PL+(N-1)Δ _RACH +Δ _Preamble , P _max }.

For normal long preamble (formats 0, 1), long preamble (formats 2, 3), and short preamble (format 4), possible settings for ΔPreamble might be, for example, 0 dB, -3 dB, and 8 dB, respectively. For a range of [-120, -90] dBm for P0 _,RACH , the valid range for P0 _,RACH -ΔPreamble now becomes [-120, -90], [-123, -93], and [-112, -82] for normal, long, and short preamble formats, respectively. These intervals better suit the typical required signal power levels for different preambles.

Another interpretation is to keep the original formula unchanged, which is:

P _RACH =min{P _{0, RACH} -PL+(N-1)Δ _RACH , P _max }

But the bit pattern signaling P _0,RACH is interpreted differently.

Table 1 shows a possible mapping of signaled P _0,RACH indices to actual P _0,RACH values.

Table 1: Signaled P0 _,RACH index mapping to different P0 _,RACH values depending on preamble format. In this example, configuration-wise preamble formats 0, 1 and 2, 3 have the same mapping.

In some embodiments, the formula for RA transmit power is modified with a further correction term based on the NCS value used to construct the RA preamble. Depending on the NCS value, different thresholds are required to maintain a certain false alarm rate. Higher threshold values improve the false alarm rate but have a negative impact on missed detections.

Here, alternative interpretations of the signaled P0 _,RACH index mapping to different P0 _,RACH values according to the NCS are possible.

We also note that the above invention is applicable even in the case where multiple preamble formats are permitted in a single cell. Depending on which preamble the UE selects to perform RA, it applies the appropriate correction term.

During the description, we assume preambles of different lengths, and they have different detection capabilities depending on the length. However, even other differences between preambles can lead to different detection capabilities. In this case, the above-mentioned invention is also applicable.

Different RA preambles require different signal powers at the eNodeB receiver to achieve the same detection performance. Embodiments propose adding a correction term to the signaled value of the required RA receive power to account for these different levels. This means that the range of values for the required receive power is better adapted to the individual preambles than without the correction.

Since the preamble format is signaled to the UE anyway, no additional signaling is required.

Referring to Figure 3, a schematic combined method and signaling scheme is shown. Signaling is performed between a first communication device 10 and a second communication device 20. In the illustrated example, the first communication device 10 comprises a user equipment, and the second communication device 20 comprises a base station. The expected receive power of the base station is based on a random access configuration parameter, which in the illustrated example is a random access preamble format. However, it should be understood that such parameters may include random access, a basic cyclic shift value, or a combination thereof.

In step S1 , the base station 20 calculates the expected received power Pdesired based on the quality standard, RA parameters, and the like.

In step S2, the base station 20 determines a pointer value indicating a power value according to Pdesired and a random access preamble format that affects detection performance of a random access operation of a user equipment at the base station.

In some embodiments, Psignaled is a calculated value from Pdesired taking into account an offset value associated with the random access preamble format. In the next step, the base station searches a table for the value Psignaled or the value closest to Psignaled. The index value corresponding to the matching/closest value is determined from the table and used as the pointer value.

In some embodiments, Pdesired is looked up in a table containing a plurality of columns each corresponding to a random access configuration parameter value. An index value corresponding to Pdesired or a value closest to Pdesired is determined from the table and used as a pointer value.

In step S3, the base station 20 transmits the pointer value to the user equipment 10 over a radio channel, for example as unicast, broadcast and/or multicast.

In step S4, the user equipment 10 receives the pointer value, reads the pointer value, and determines the random access transmit power to be used.

In some embodiments, the user equipment 10 uses the pointer value in the table to look up Psignaled. Pdesired is determined based on Psignaled and the random access preamble format known from previous signaling or determined by the user equipment based on a received signal carrying the pointer value. For example, an offset power value based on the preamble format is added to Psignaled. Pdesired is then used to determine the random access transmit power to be used.

In some embodiments, the user equipment 10 determines Pdesired using the pointers in the rows and columns of the table together with the random access preamble format, the pointer value defining the row and the random access preamble format defining the column.

In step S5, the user equipment sets itself in an operation mode configured to use the determined random access transmission power.

In step S6, the user equipment performs a random access procedure and transmits random access data to the base station using the determined random access transmission power through a radio channel.

Figure 4 shows a schematic flow chart of a method in a first communication device for designing a transmit power setting for the first communication device that takes into account random access configuration parameters that affect random access detection performance at a second communication device. These parameters may include a preamble format, a basic cyclic shift value, and the like.

The first communication device receives data indicating the expected random access reception power from the second communication device over the radio channel in step 42. The data may be a pointer value to be used in a table or the like.

In step 44 , the first communication device determines the expected random access reception power of the second communication device according to the received data and a random access configuration parameter that affects the random access detection performance of the second communication device.

In some embodiments, the received data includes a pointer value indicating a signaled random access received power in a random access received power table, and determining the expected random access received power is based on the signaled random access received power and a random access configuration parameter. Determining the expected random access received power may further include calculating the expected random access received power by adding or subtracting an offset value from the signaled random access received power, wherein the offset value is based on the random access configuration parameter.

In some alternative embodiments, the received data includes a pointer value indicating an expected random access received power in a table of expected random access received powers, and the step of determining the expected random access received power includes using the pointer value in the table together with a random access configuration parameter. In some embodiments, the table may include rows and columns defined by the pointer value and the random access configuration parameter value.

In step 46, the first communication device determines the random access transmission power to be used according to the expected random access reception power.

In some embodiments, the step of determining the expected random access transmission power to be used further comprises taking into account a power path loss between the first communication device and the second communication device.

In step 48, the first communication device sets itself in an operation mode using the determined random access transmission power.

In optional step 50, the first communications device performs a random access procedure using the determined random access transmit power.

In order to perform the method, a first communication device is provided. The first communication device may be: user equipment, such as a mobile phone, a PDA, a laptop computer; a base station; a controller; or a combination thereof.

FIG5 shows a schematic overview of a first communication device, shown as a user equipment. The first communication device 10 is configured to communicate with a second communication device to set a transmit power setting design for the first communication device that takes into account random access configuration parameters that affect random access transmission detection performance at the second communication device. Such parameters may include a preamble format, a basic cyclic shift value, and the like.

The first communication device 10 comprises a receiving arrangement 103 configured to receive a signal indicating a random access reception power from a second communication device on a radio channel in order to detect a random access transmission from the first communication device.

The first communication device 10 further includes a control unit 101 configured to determine an expected random access receive power of the second communication device based on the received data and a random access configuration parameter that affects the random access transmission detection performance of the second communication device. The control unit 101 is further configured to determine a random access transmit power design setting based on the expected random access receive power. In some embodiments, the control unit 101 is further configured to consider a power path loss between the first communication device and the second communication device in order to determine the random access transmit power.

In some embodiments, the received data may include a pointer value configured to indicate a signaled random access received power in a random access received power table stored in the memory unit 107 of the first communication device. The control unit 101 is then configured to determine the expected random access received power based on the signaled random access received power pointer and the random access configuration parameter.

In addition, the control unit 101 may be further configured to calculate the expected random access received power by adding/subtracting an offset value to the signaled random access received power, wherein the offset value is based on a random access configuration parameter.

In some alternative embodiments, the received data includes a pointer value indicating an expected random access received power in a table of expected random access received powers stored in the memory unit 107 of the first communication device. The control unit 101 is then configured to use the pointer value in the table together with the random access configuration parameter to determine the expected random access received power. The table may include rows and columns defined by the pointer value and the random access configuration parameter value.

In some embodiments, the memory unit 107 has data and/or tables stored thereon and an application program arranged to run on the control unit 101 to perform a method.

In some embodiments, the control unit 101 may be arranged to perform a random access operation using a random access transmission power design and transmit the random access request to the second communication device or a different communication device via the transmission arrangement 105 of the first communication device.

The first communication device includes a UE, a base station, a base station controller, etc.

In FIG6 , a schematic overview of a method for transmitting data via a radio channel in a second communication device is shown.

In step 52, the second communication device determines the expected random access reception power from the first communication device, so that the second communication device can detect the random access request from the first communication device using random access configuration parameters that affect random access detection performance at the second communication device.

In step 54, the second communication device determines data according to the expected random access reception power and the random access configuration parameters. The random access configuration parameters include the preamble format, the basic cyclic shift value of the random access configuration, and the like.

In some embodiments, the second communication device further determines a signaled random access received power based on the expected random access received power and the random access configuration parameter, and then retrieves a pointer value from the signaled random access received power table based on the determined signaled random access received power, and then includes it in the data.

In some embodiments, the signaled random access received power may be calculated from the expected random access received power and an offset value, wherein the offset value is based on a random access configuration parameter.

In some embodiments, the second communications device further determines a pointer in a table of expected random access received power. The pointer value is determined based on the determined expected random access received power and a random access configuration parameter. The data includes the pointer value, and the table may be an expected random access received power table comprising rows and columns defined by the pointer value and the random access configuration parameter value.

In step 56, the second communication device transmits the data to the first communication device over the radio channel.

In order to perform the method, a second communication device is provided, which may include a base station, a controller, a user equipment, a combination thereof, etc.

In FIG. 7 , a schematic overview of the second communication device 20 is shown.

The second communication device 20 comprises a control unit 201 arranged to determine an expected random access reception power from the first communication device such that the second communication device can detect a random access request from the first communication device.

The control unit 201 is further configured to determine data based on the expected random access reception power and random access configuration parameters that affect the random access detection performance of the second communication device. The random access configuration parameters may include a preamble format, a basic cyclic shift value of the random access configuration, and the like.

In some embodiments, the control unit 201 is further configured to determine a signaled random access received power based on the expected random access received power and the random access configuration parameters stored in the memory unit 207. Furthermore, the control unit 201 is configured to determine a pointer value from a signaled random access received power table based on the determined signaled random access received power. The transmitted data then includes the determined pointer value.

It should be noted here that the control unit 201 may be configured to calculate the expected signaling random access transmit receive power by using the expected random access receive power and an offset in the calculation, wherein the offset value is related to the random access configuration parameter.

In some alternative embodiments, the transmitted data includes a pointer value, and the control unit 201 is configured to determine the data by determining a pointer value in a table of expected random access received power. The pointer value is configured to be determined based on the determined expected random access received power and a random access configuration parameter. The table includes rows and columns defined by the pointer value and the random access configuration parameter value.

The second communication device 20 further comprises a transmitting arrangement 205 configured to transmit data to the first communication device over the radio channel.

The second communication device includes a base station, a base station controller, a UE, etc.

In some embodiments, the memory unit 207 has data and/or tables stored thereon and an application arranged to run on the control unit 201 to perform the method. The second communication device 20 may further comprise a network interface 209 for communicating with a communication network and a receiving arrangement 203 arranged to receive random access requests or the like.

In the drawings and the specification, exemplary embodiments of the present invention are disclosed. However, many variations and modifications may be made to these embodiments without departing substantially from the principles of the present invention. Therefore, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the present invention being defined by the appended claims.

Claims (12)

1. A method for random access in a user equipment (10) within a Long Term Evolution (LTE) network, comprising the following steps: -Receive data from base station (20) (42) on the radio channel, specifying the random access receive power. - Random access data is transmitted (50) using random access transmit power, which is determined based on the received data and random access configuration parameters affecting the random access detection performance at the base station (20), and also based on a power ramp set to increase the random access transmit power based on the number of transmit attempts and the power path loss between the user equipment (10) and the base station (20), wherein the parameters include the preamble format and/or the basic cyclic shift value of the preamble. 2. The method of claim 1, further comprising: Based on the received data and the parameters, the expected random access receive power of the base station (20) is determined (44), and The random access transmit power to be used is calculated based on the expected random access receive power and the power ramp, and also taking into account the power path loss. 3. The method of claim 2, wherein the random access transmit power is based on an offset value of the parameters including the preamble format. 4. The method of any one of claims 1-3, wherein the random access transmit power is based on the preamble format correlated offset. 5. The method of any one of claims 1-3, wherein the power path loss includes the difference between the received power and the transmitted power for one or more reference signals having a known transmit power. 6. The method of any one of claims 1-3, wherein the random access transmit power is determined based on the following formula: P _RACH =min {P _{0, RACH} -P _L + (N-1)Δ _RACH +Δ _Preamble , P _max } in: P _RACH includes random access transmit power. P0 _,RACH includes the specified random access receive power. PL includes power path loss. _ΔRACH includes power ramp-up, N includes the number of launch attempts. _ΔPreamble includes offset values for the parameters, including the preamble format and/or the basic cyclic shift values of the preamble, and _Pmax includes the maximum random access transmit power. 7. A user equipment (10) configured to be included in a Long Term Evolution (LTE) network, the user equipment comprising: Receiver (103) is configured to receive data indicating random access reception power from base station (20) on a radio channel to detect random access transmissions, and The transmitter is configured to transmit random access data using random access transmit power, which is determined based on the received data and random access configuration parameters affecting the random access detection performance at the base station (20), and also based on a power ramp that is set to increase the random access transmit power based on the number of transmit attempts and the power path loss between the user equipment (10) and the base station (20), wherein the parameters include the preamble format and/or the basic cyclic shift value of the preamble. 8. The user equipment (10) as claimed in claim 7, further comprising a control unit (101), the control unit (101) being configured to: The expected random access receive power of the base station (20) is determined based on the received data and the parameters, and The random access transmit power to be used is calculated based on the expected random access receive power and the power ramp, and also taking into account the power path loss. 9. The user equipment (10) of claim 8, wherein the random access transmit power is based on an offset value of the parameters including a preamble format. 10. The user equipment (10) as claimed in any one of claims 7-9, wherein the random access transmit power is based on the preamble format correlated offset. 11. The user equipment (10) of any one of claims 7-9, wherein the power path loss includes the difference between the received power and the transmitted power for one or more reference signals having a known transmit power. 12. The user equipment (10) as claimed in any one of claims 7-9, wherein the random access transmit power is determined based on the following formula: P _RACH =min{P _{0, RACH} -PL+(N-1)Δ _RACH +Δ _Preamble , P _max } in: P _RACH includes random access transmit power. P0 _,RACH includes the specified random access receive power. PL includes power path loss. _ΔRACH includes power ramp-up, N includes the number of launch attempts. _ΔPreamble includes offset values for the parameters, including the preamble format and/or the basic cyclic shift values of the preamble, and _Pmax includes the maximum random access transmit power.