Radio communication system, radio transmission device, and RACH transmission method
View Patent ↗Disclosed are a radio communication system, a radio transmission device, and a Random Access Channel (RACH) transmission method capable of reducing the important information conflict probability and improving the communication system throughput in a channel transmitted at a random timing such as RACH. In a frame configuration used by the communication system, the number of slots of RACH is reduced by one and the resource for the slot is equally allocated as a resource for a pilot/User Equipment-Identification (UE-ID) of other slots. This increases the resource amount of the pilot/UE-ID. Furthermore, the resource of the pilot/UE-ID is divided into a plurality of sub slots, which are allocated as resource blocks for respective mobile stations.
1. A radio communication apparatus in which resource blocks for a channel transmitted between the radio communication apparatus and a plurality of other radio communication apparatuses at random timings comprise a first resource block and a second resource block, the radio communication apparatus comprising:
a transmission slot selecting section that selects one transmission slot from a plurality of transmission slots on a random basis;
a subslot selecting section that selects a subslot from a plurality of subslots forming a first part of the selected transmission slot on a random basis;
a first allocation section that allocates data to be prevented from collision to the first resource block allocated to the selected subslot;
a second allocation section that allocates data other than the data to be prevented from collision to the second resource block allocated to a second part of the selected transmission slot; and
a transmission section that transmits the first resource block and the second resource block to which the data is allocated.
2. The radio communication apparatus according to claim 1 , wherein a proportion of the first resource blocks with respect to all of the resource blocks for the channel is set to be greater than a proportion of the second resource blocks.
3. The radio communication apparatus according to claim 2 , wherein a number of the radio communication apparatuses allocated to the first resource blocks is set greater than a number of the radio communication apparatuses allocated to the second resource blocks.
4. The radio communication apparatus according to claim 1 , further comprising a changing section that adaptively changes a proportion of the first resource blocks with respect to all of the resource blocks for the channel.
5. The radio communication apparatus according to claim 4 , wherein the changing section adaptively changes the proportion of the first resource blocks in accordance with an access condition of the plurality of other radio communication apparatuses.
6. The radio communication apparatus according to claim 4 , wherein the changing section changes the proportion of the first resource blocks based on information received from the plurality of other radio communication apparatuses.
7. The radio communication apparatus according to claim 6 , wherein the information received from the plurality of other radio communication apparatuses is information related to access conditions of the plurality of other radio communication apparatuses.
8. The radio communication apparatus according to claim 7 , wherein the changing section changes the proportion of the first resource blocks to be greater when the information related to the access conditions shows an access increase.
9. The radio communication apparatus according to claim 1 , further comprising:
a first attaching section that attaches a first cyclic prefix to the first resource block; and
a second attaching section that attaches a second cyclic prefix to the second resource block,
wherein the first attaching section sets a signal length of the first cyclic prefix to be greater than a signal length of the second cyclic prefix.
10. The radio communication apparatus according to claim 1 , wherein the first allocating section allocates an identification of the radio communication apparatus to the first resource block.
11. The radio communication apparatus according to claim 1 , wherein the first resource block comprises a plurality of frequency division blocks dividing a common time slot in a frequency direction.
12. The radio communication apparatus according to claim 1 , wherein the first resource block is further divided into resource blocks for the radio communication apparatuses.
13. The radio communication apparatus according to claim 1 , wherein identification information and a pilot for each of the radio communication apparatuses are used as the data to be prevented from collision.
14. The radio communication apparatus according to claim 1 , wherein a random access channel is used for the channel.
15. The radio communication apparatus according to claim 1 , wherein a contention based channel is used for the channel.
16. The radio communication apparatus according to claim 1 , further comprising a transmission slot type setting section that selects a transmission slot type used for transmission from a plurality of transmission slot types, proportions of the plurality of transmission slot types being different between the first resource block and the second resource block,
wherein the transmission section transmits the first resource block and the second resource block to which the data is allocated, using the selected transmission slot type.
17. The radio communication apparatus according to claim 16 , wherein in the transmission slot type setting section, the plurality of transmission slot types are associated per frequency, and the transmission slot type setting section selects a transmission slot type in which a proportion of the first resource blocks is high when a number of retransmissions of the channel is high, or selects a transmission slot type in which the proportion of the first resource blocks is low when a number of retransmissions of the channel is low.
18. A communication terminal apparatus comprising the radio communication apparatus according to claim 1 .
19. A base station apparatus comprising the radio communication apparatus according to claim 1 .
20. A random access channel transmission method performed by a radio communication apparatus in which resource blocks for a channel transmitted between the radio communication apparatus and a plurality of other radio communication apparatuses at random timings comprise a first resource block and a second resource block, the random access channel transmission method comprising:
selecting one transmission slot from a plurality of transmission slots on a random basis;
selecting a subslot from a plurality of subslots forming a first part of the selected transmission slot on a random basis;
allocating data to be prevented from collision to the first resource block allocated to the selected subslot;
allocating data other than the data to be prevented from collision to the second resource block allocated to a second part of the selected transmission slot; and
transmitting the first resource block and the second resource block to which the data is allocated.