The upstream channel of 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) employs contiguous band transmission in which a data signal of each terminal is allocated to contiguous frequency band to reduce CM/PAPR (Cubic Metric/Peak to Average Power Ratio). Each terminal transmits data according to frequency allocation resource information notified from a base station. The frequency allocation resource information means two pieces of information that include a start RB (Resource Block) number and an end RB number where the term “RB” indicates a frequency allocation unit formed of twelve subcarriers.
In an LTE network, the base station notifies the terminals of the frequency allocation resource information using information referred to herein as RIV (Resource Indication Value). RIV indicates the allocation resource information with a tree structure as shown in FIG. 1. FIG. 1 shows the RIV tree structure that indicates contiguous band allocation within RB#0 to RB#5. When the base station designates RIV=6, for example, the allocation resource information for the terminal includes RB#0 and RB#1 that are the base of the tree. Similarly, when the base station designates RIV=14, allocation resource information for the terminal includes RB#2 to RB#4 that are the base of the tree. RB#0 to RB#5 located at the base of the tree correspond to RIVs=0 to 5, respectively.
Assuming that RIVs=0 to 5 at the base of the tree are the first step, RIVs=6 to 10, RIVs=12 to 15, RIVs=18 to 20, RIVs=17 to 16, and RIV=11 correspond to the second, third, fourth, fifth, and sixth steps, respectively. Utilization of the first to sixth RIVs enables the contiguous band with twenty-one patterns to be indicated out of RB#0 to RB#5 located at the base of the tree.
It is studied that the upstream channel of LIE-Advanced as an evolved form of LTE employs non-contiguous band transmission in addition to the contiguous band transmission to improve sector throughput performance (see Non-Patent Literature 1).
The non-contiguous band transmission is a transmission method of allocating data signals and reference signals to non-contiguous bands that are distributed over a wide band. The non-contiguous band transmission can allocate the data signals and the reference signals to discrete frequency bands as shown in FIG. 2. Thus, the non-contiguous band transmission can increase the degree of freedom of frequency band allocation of the data signal and the reference signal at each terminal to have a larger frequency scheduling effect compared to the contiguous band transmission.
A conventional method of sending the non-contiguous band allocation resource information from the base station to the terminals is to notify any terminal of the non-contiguous band allocation by sending a plurality of RIVs (contiguous band allocation information) to the terminal (see Non-Patent Literature 2).
As shown in FIG. 3, NPL 2 discloses that RBG numbers (RBG#) are assigned by allocation granularity (4 RB in FIG. 3) referred to herein as RBG (Resource Block Group) and the scheduled terminal is notified of RIV indicating a start RBG# and an end RBG#. The base station notifies the terminal of two RIVs (RIV#1 and RIV #2) as shown in FIG. 3, thereby enabling allocation of two clusters (each being a contiguous band block), i.e., non-contiguous bands to the terminal. Thus, specifying RBG by taking advantage of RIVs themselves used in conventional LTE enables non-contiguous band allocation to be easily introduced into LTE-Advanced.
An RBG size is determined according to a system bandwidth as shown in FIG. 4. For the system bandwidth of 20 MHz, for example, the RBG size will be 4 RB as shown in FIG. 3. The number of signaling bits of the allocation resource information is thus reduced by increasing RBG size according to the magnitude of the system bandwidth.