Method for realizing contention resolution in mobile communication system

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a mobile communication system and, more particularly, to a method for realizing contention resolution in a mobile communication system.

Discussion of Related Art

The contention is not the collision of physical parameters such as access slot, preamble signature and spreading code but the collision of mobile IDs of mobile stations. In a mobile communication system, mobile stations are divided from one another according to physical parameters. The contention that is the synchronization of mobile IDs of mobile stations occurs when the mobile stations use the same preamble signature in the same slot. A conventional method for realizing contention resolution in the mobile communication system is explained below with reference to the attached drawing. Fig. 1 is a flow chart showing the conventional method for realizing contention resolution in the mobile communication system.

Referring to Fig. 1, a first mobile station attempt at random access to a base station with a first random mobile ID through a common channel in order to request multi-service. A second mobile station tries random access to the base station with the first random mobile ID used by the first mobile station through a random access channel, having a predetermined time difference from the random access of the first mobile station. The first and second random mobile IDs of the first and second mobile stations are used when their physical parameters of preamble signals and access slots are identical or different to/from each other.

The base station performs the following operation according to the random access of the first and second mobile stations. When the first random mobile ID and random access from the first and second mobile stations collide with each other so that the base station cannot receive any signal, the base station transmits no signal to the first and second mobile stations. Then, the mobile stations retried the random access after the lapse of a predetermined time of their inner timers. When the base station received a signal according to the random access of the first random mobile ID from the first mobile station but did not receive a signal according to the random access of the first random mobile ID from the second mobile station, it broadcasts an access grant signal ACK of the first random mobile ID, informing that it received the random access from the first mobile station. Accordingly, dedicated channels are assigned to the first and second mobile stations according to the access grant signal ACK of the first random mobile ID, which is broadcasted by the base station, resulting in generation of contention.

Specifically, because the second mobile station received the access grant signal ACK from the base station using the first random mobile ID which was random-accessed by itself although the random access of the first random mobile ID was not received by the base station, the second mobile station misrecognizes that its random access is successful. Thus, the dedicated channel contained in the acknowledge signal ACK of the first random mobile ID is assigned to the second mobile station. Accordingly, the first and second mobile stations transmit signals including directory numbers, which are their identities, through the dedicated channels assigned thereto.

Then, the base station searches the directory numbers included in the signals received through the dedicated channels from the first and second mobile stations, duplicates a signal including the directory number of the first mobile station to the first mobile station having the mobile ID, which succeeded in the random access, and then broadcasts it. The first mobile station compares the signal including its directory number, which has been broadcasted by the base station, with the signal which has been transmitted by itself, and continuously performs communication because the two signals are identical to each other. The second mobile station compares the signal ACK including its directory number, which has been transmitted from the base station, with the signal which has transmitted by itself. Then, the second mobile station tries random access again or stops it after the lapse of a predetermined time of its inner timer because the two signals are different from each other. By doing so, resolution of the contention generated between the first and second mobile stations is realized.

The base station makes resolution of the contention generated between the first and second mobile stations through the aforementioned procedure when it received the signal according to the random access of the first random mobile ID from the second mobile station but did not receive the signal according to the random access of the first random mobile ID from the first mobile station.

However, the conventional method for realizing contention resolution in the mobile communication system unnecessarily consumes electric power, deteriorates the performance of the system or generates interference when contention resolution due to attempt at random access of the same mobile ID occurs because the base station receives random access signal and transmits the access grant message in case that a plurality of mobile stations try the random access with the same mobile ID that has identical or different physical parameters.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for realizing contention resolution in a mobile communication system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method for realizing contention resolution in a mobile communication system, in which a plurality of mobile stations construct different mobile identities of physical parameters of different preamble signal regions and access slot regions, to attempt at random access, thereby resolving contention.

To accomplish the object of the present invention, there is provided a method for realizing contention resolution in a mobile communication system, in which a plurality of mobile stations try random access to a base station, the method including the steps of the mobile stations generating different mobile IDs according to physical parameters, the mobile stations trying random access using the generated mobile IDs, and the base station including the mobile IDs in access grant signals and broadcasting them.

Each of the mobile IDs consists of a preamble signature region, an access slot region, and a random number region. The preamble signature region, access slot region, and random number region are 4-bit, 3-bit and 9-bit, respectively.

To accomplish the object of the present invention, there is also provided a method for realizing contention resolution in a mobile communication system, in which a plurality of mobile stations generate mobile IDs in order to try random access to a base station, the method including the steps of generating the mobile IDs using at least two physical parameters, and trying the random access using the generated mobile IDs.

Each of the mobile IDs consists of a preamble signature region, an access slot region, and a random number region.

According to the present invention, a plurality of mobile stations construct different mobile identities of physical parameters of different preamble signal regions and access slot regions, to try random access, thereby preventing unnecessary power consumption, deterioration of the performance of the system and interference due to the contention resolution.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention:

In the drawings: <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 is a flow chart showing a conventional method for realizing contention resolution in a mobile communication system;</li><li>Fig. 2 shows an example of a format of a mobile identity applied to a method for realizing contention resolution in a mobile communication system according to the present invention; and</li><li>Fig. 3 is a flow chart showing a method for realizing contention resolution in a mobile communication system according to the present invention.</li></ul>

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Fig. 2 shows an example of a format of a mobile identity applied to a method for realizing contention resolution in a mobile communication system according to the present invention. Referring to Fig. 2, the mobile identity consists of a 4-bit preamble signature region, a 3-bit access slot region and a random number region. Fig. 3 is a flow chart showing a method for realizing contention resolution in a mobile communication system according to the present invention. There is described below the method for realizing contention resolution in a mobile communication system according to the present invention with the reference to the attached drawings.

In case that first and second mobile stations try random access to a base station, they assign mobile IDs different from each other to attempt at random access in order to prevent contention. Specifically, radio resource controls (RRCs) of the first and second mobile stations generate random numbers in the physical parameters of the preamble signature region and access slot region and in the random number region, to assign different mobile IDs, and then attempt at random access. The preamble signature region, access slot region and random number region are 4-bit, 3-bit and 9-bit, respectively.

The mobile ID is divided into several sections, and each bit is determined by the physical parameters. The number of bits can be changed, and the mobile ID of the mobile station can be varied when the physical parameters are changed. For example, the RRC of the first mobile station generates random numbers in the physical parameters of the "0110" preamble signature region and "110" access slot region and the random number region, to assign a first mobile ID (ID1), and then attempts at random access. The RRC of the second mobile station generates random numbers in the physical parameters of the "1110" preamble signature region and "010" access slot region and the random number region, to assign a second mobile ID (ID2), and then attempts at random access.

Then, the base station searches a reception state of the random access received from the first and second mobile stations, to detect a mobile ID of the received random access signal, and then transmits access grant signals ACK to the mobile station having the mobile ID. That is, when only the random access of the first mobile ID (ID1) is received from the first mobile station, the base station broadcasts the access grant signals ACK to the first mobile station having the first mobile ID (ID1). Accordingly, the first mobile station searches the access grant signals ACK, which are broadcasted from the base station, to receive the access grant signal ACK of its first mobile ID, and then performs communication through a dedicated channel which is assigned by the base station to be contained in the access grant signal ACK. The second mobile station attempts at random access again using another mobile ID or stops it after the lapse of a predetermined time of its inner timer because it did not receive the access grant signal ACK of its second mobile ID from the base station.

In case that the base station has received only the random access of the second mobile station, it broadcasts access grant signals ACK to the second mobile station having the second mobile ID (ID2). Accordingly, the second mobile station searches the access grant signals ACK, which are broadcasted from the base station, to receive the access grant signal ACK of its second mobile ID, and then performs communication through a dedicated channel which is assigned by the base station to be contained in the access grant signal ACK. The first mobile station attempts at random access again using another mobile ID or stops it after the lapse of a predetermined time of its inner timer because it did not receive the access grant signal ACK of its first mobile ID from the base station.

According to the method for realizing contention resolution in a mobile communication system of the present invention, a plurality of mobile stations construct different mobile identities of physical parameters of different preamble signal regions and access slot regions, to attempt at random access, thereby preventing unnecessary power consumption, deterioration of the performance o system and interference due to the contention resolution.

It will be apparent to those skilled in the art that various modifications and variations can be made in the method for realizing contention resolution in a mobile communication system of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.