Obviousness

Obviousness Analysis of US Patent 8411557 Under 35 U.S.C. § 103

This analysis addresses the obviousness of US Patent 8411557 ("Mobile station apparatus and random access method") under 35 U.S.C. § 103, considering the provided prior art references and a priority date of March 20, 2006.

Claims for Analysis:
The independent claims of US8411557 are Claim 1 (mobile station apparatus) and Claim 10 (random access method). Both claims share the same core inventive concepts. For brevity, the analysis will primarily focus on Claim 1, with the understanding that the reasoning applies equally to the method claim.

Claim 1 recites:

A mobile station apparatus comprising:
a receiving unit configured to receive control information;
a selecting unit configured to randomly select a sequence from a plurality of sequences contained in one group of a plurality of groups, into which a predetermined number of sequences that are generated from a plurality of base sequences are grouped and which are respectively associated with different amounts of data or reception qualities, wherein the predetermined number of sequences are grouped by partitioning the predetermined number of sequences, in which sequences generated from the same base sequence and having different cyclic shifts are arranged in an increasing order of the cyclic shifts; and
a transmitting unit configured to transmit the selected sequence,
wherein a position at which the predetermined number of sequences are partitioned is determined based on the control information, and a number of sequences contained in each of the plurality of groups varies in accordance with the control information.

Combinations of Prior Art and Motivation:

A person having ordinary skill in the art (PHOSITA) in the field of radio communication systems (specifically 3GPP LTE random access) would have found the claimed mobile station apparatus and method obvious based on a combination of:

• Non-patent Document 2 (NPT2): NTT DoCoMo, NEC, Sharp, “Orthogonal Pilot Channel Structure in E-UTRA Uplink,” R1-060046, Jan. 2006.
• Non-patent Document 3 (NPT3): Qualcomm, “Principles of RACH,” R1-060480, Feb. 2006.
• WO2006019710A1 (Qualcomm): “Efficient signaling over access channel,” published Feb. 23, 2006.
• US20020041578A1 (Samsung): “Method for selecting RACH in a CDMA mobile communication system,” published Apr. 11, 2002.

Detailed Obviousness Argument:

1. Receiving Control Information and Transmitting a Selected Sequence:
The "receiving unit configured to receive control information" and "transmitting unit configured to transmit the selected sequence" are fundamental elements of a mobile station involved in random access, as widely known in the prior art. The background of US8411557 itself states that mobile stations transmit RACH signals by selecting unique signatures. NPT3 describes that random access channels (RACH) are used to report "control information including the mobile station ID, the reason for RACH transmission, bandwidth allocation request information (QoS information, the amount of data, and so on), and downlink received quality information". Thus, a mobile station would inherently receive or determine the control information it needs to report and then transmit a corresponding random access sequence.

2. Generating Sequences from Base Sequences with Cyclic Shifts and Associating with Control Information:
NPT2 teaches the use of CAZAC (Constant Amplitude Zero Auto-Correlation) sequences, which are a type of GCL (Generalized Chirp-Like) sequence, as signatures in the E-UTRA Uplink. NPT2 explicitly discusses generating "a plurality of derived code sequences C k,m (n) of respective numbers of cyclic shifts" from a base code sequence. These derived sequences possess "lowest cross-correlation among GCL sequences", making them ideal for distinguishing signals from multiple mobile stations.

WO2006019710A1 teaches that "preambles can be utilized to convey information such as channel quality indication (CQI), a scheduling request, a power headroom, or other control information". Similarly, NPT3 states that RACH preambles can carry information such as "amount of data" or "downlink received quality information".

A PHOSITA would be motivated to combine NPT2 and WO2006019710A1/NPT3. The robust, orthogonal sequences generated by cyclic shifts from base sequences (as described in NPT2) provide an excellent set of "predetermined number of sequences" that can be used as preambles to efficiently signal the various types of control information (e.g., amounts of data or reception qualities) as suggested by WO2006019710A1 and NPT3. This combination addresses the problem of efficiently reporting control information in the RACH while maintaining good detection performance. The selection of one of these sequences for transmission would be random among available sequences to reduce collision in a contention-based RACH environment, a well-known principle in wireless communication, also acknowledged in the background of US8411557.

3. Grouping by Partitioning Sequences with Different Cyclic Shifts and Varying Group Size Based on Control Information:
The unique aspects of Claim 1 relate to:

• "a predetermined number of sequences... are grouped by partitioning the predetermined number of sequences, in which sequences generated from the same base sequence and having different cyclic shifts are arranged in an increasing order of the cyclic shifts"
• "a position at which the predetermined number of sequences are partitioned is determined based on the control information, and a number of sequences contained in each of the plurality of groups varies in accordance with the control information."

Given the disclosure of NPT2, a PHOSITA would inherently understand that sequences derived from a base sequence via cyclic shifts can be logically "arranged in an increasing order of the cyclic shifts" for management. The next step is "grouping" these sequences and associating them with control information. WO2006019710A1 and NPT3 already teach associating sequences with control information like "amount of data" or "reception qualities." The grouping is a logical consequence of this association.

The key lies in varying the number of sequences in each group based on the control information. US20020041578A1 provides the motivation for this. It describes a method for selecting a RACH based on the current load status of available RACHs or based on quality of service (QoS) requests. "Load status" is directly correlated with the "rate of occurrence" of requests for certain types of control information.

Motivation for Combining with US20020041578A1:
A PHOSITA would be motivated to combine the sequence generation and information-carrying mechanisms (from NPT2 and WO2006019710A1/NPT3) with the load-aware RACH selection of US20020041578A1. The problem of RACH collisions, particularly when many mobile stations attempt to report similar control information (e.g., a specific QoS requirement or low reception quality, which might have a high rate of occurrence in certain cell areas), is a known issue. US20020041578A1 identifies "load status" as a factor for RACH selection to mitigate such problems.

Therefore, it would have been obvious to a PHOSITA to dynamically adjust the resources (i.e., the number of available sequences) allocated to different types of control information. If a particular "amount of data" or "reception quality" (control information) is frequently reported (high load/rate of occurrence), a PHOSITA would naturally allocate a larger "group" of unique sequences (generated from base sequences with cyclic shifts from NPT2) to that specific control information type. This "partitioning" of the predetermined number of sequences would result in a "number of sequences contained in each of the plurality of groups" that "varies in accordance with the control information" (e.g., higher occurrence rate leads to a larger group size). The "position at which the predetermined number of sequences are partitioned" would consequently be determined by these dynamic allocation decisions based on the control information and its associated load/occurrence probability. This adaptive allocation directly addresses the problem of reducing collisions and improving the efficiency of control information reporting, as highlighted in US8411557 itself (e.g., in paragraph regarding reducing collisions for high-occurrence control information).

Conclusion:
Considering NPT2, NPT3, WO2006019710A1, and US20020041578A1, a PHOSITA would have possessed the necessary knowledge and motivation to combine these references. The combination would lead to a mobile station apparatus and method that generates sequences using cyclic shifts, associates these sequences with different types of control information (like data amount or reception quality), and dynamically adjusts the number of sequences allocated to each control information type based on factors like load or rate of occurrence. This combination would achieve the advantageous effects of efficient control information reporting and reduced RACH collisions, as claimed by US8411557, making Claim 1 and Claim 10 obvious.