Obviousness

Obviousness Analysis of US Patent 8311040 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US patent 8311040 obvious to a person having ordinary skill in the art (PHOSITA). The analysis is grounded in the explicit descriptions of prior art within US8311040B2 itself, and the content of the patent documents for the cited related applications.

1. Claims at Issue

The independent claims of US8311040B2 are Claim 1 (method) and Claim 9 (system), which describe:

• Receiving a plurality of service data units (SDUs) of different lengths.
• Packing these SDUs and fragments of SDUs into at least one protocol data unit (PDU).
• Forming packing subheaders that reflect the length of at least some of the SDUs.
• Including at least two fragmentation control bits in the PDU header, indicating the absence or presence and orientation of fragments of SDUs in the PDU.

2. Person Having Ordinary Skill in the Art (PHOSITA)

A PHOSITA in the field of US8311040B2 would be a professional with a background in telecommunications, networking, or computer engineering, possessing experience in packet data communication systems, network protocols (e.g., ATM, IP, MAC), and wireless communication technologies. This individual would understand concepts such as SDUs, PDUs, frames, physical layer mapping, modulation, and error correction. They would be motivated by the constant pursuit to efficiently utilize the finite capacity of communication links and increase data throughput, as articulated in the background of US8311040B2.

3. Prior Art References

The following prior art references are explicitly mentioned or incorporated by reference in US8311040B2 and are relevant for this analysis:

• General Knowledge (GK): The background of US8311040B2 itself acknowledges that data communication systems typically transfer data in packets (SDUs and PDUs), that links have physical bandwidth limits, and that efficient utilization is a constant pursuit. It also states that "Fragmenting is a method of partitioning a packet of data into two or more smaller pieces to be conveyed over a communications link that utilizes packets; and it is accomplished when the packet is too large for the existing bandwidth of a current frame or communications cycle." This indicates that the concepts of packing (for efficiency) and fragmentation were generally known.
• US7075953B2 (the '293 application): Titled "COMPRESSION OF OVERHEAD IN LAYERED DATA COMMUNICATION LINKS," this patent (filed Oct. 30, 2000) describes a method and system for data communication where a service data unit (SDU) is converted into a protocol data unit (PDU). The primary focus is on "reducing redundant SDU header information" when converting the SDU to the PDU to minimize overhead. US8311040B2 states that the methods described therein "may be employed with the system modules described in the '293 application to form an improved system for transporting data across a communications link."
• WO2001054366A2 (the '687 application): Titled "METHOD AND APPARATUS FOR DATA TRANSPORTATION AND SYNCHRONIZATION BETWEEN MAC AND PHYSICAL LAYERS IN A WIRELESS COMMUNICATION SYSTEM," this PCT application (filed Oct. 27, 2000) describes forming PDUs at the MAC layer, assigning them to Physical Layer Information Elements (PIs) at the Physical Layer, and transmitting the PIs. It specifically discloses that "a plurality of PDUs can be assigned to a single PI or a single PDU can be assigned to a plurality of PIs" and that "The PDU can be segmented into a plurality of PDU segments and assigned to a plurality of PIs." US8311040B2 notes that "The mapping from PDU to PHY in the '687 application discloses a means of converting PDUs to a form appropriate for transmission by a wireless link."

4. Obviousness Analysis

A PHOSITA, motivated by the recognized need to "maximize the efficiency of communications links having a finite bandwidth" and effectively handle "data in various formats" (i.e., variable-length SDUs), would find it obvious to combine the general knowledge of packing and fragmentation with the specific teachings of US7075953B2 and WO2001054366A2 to arrive at the claimed invention of US8311040B2.

Motivation to Combine:
The '293 application (US7075953B2) directly addresses the efficiency of SDU-to-PDU conversion by reducing overhead. The '687 application (WO2001054366A2) demonstrates efficient data handling (segmentation and packing) at a lower layer (PDU to PI). A PHOSITA would logically extend these established principles of efficiency, segmentation, and packing to the SDU-to-PDU conversion layer to achieve comprehensive bandwidth optimization for varied SDU sizes. The problem of fitting variable-length data into fixed or flexibly sized transport units, while minimizing overhead, is a persistent one in networking, thus providing a strong motivation for a PHOSITA to combine known solutions.

Combination Rationale:

1. Receiving variable-length SDUs and Packing SDUs and fragments of SDUs into a PDU:

   • General knowledge (GK) teaches that both packing (to utilize available space efficiently) and fragmentation (to handle data larger than the available space) are techniques for efficient data transmission. The background of US8311040B2 explicitly recognizes the need to efficiently utilize bandwidth for variable-length SDUs.
   • US7075953B2 focuses on efficient SDU-to-PDU conversion. WO2001054366A2 demonstrates that data units can be segmented and packed at a lower layer (PDUs into PIs). A PHOSITA would logically apply these concepts at the SDU-to-PDU layer. If an SDU is too large for a PDU, it must be fragmented. If a PDU has remaining capacity after accommodating an SDU or fragment, packing additional (potentially fragmented) SDUs is a straightforward and predictable step to maximize payload efficiency, driven by the goal of "maximizing the efficiency of communications links."

2. Forming packing subheaders, at least some of which reflect the length of at least some of the SDUs:

   • When multiple, variable-length data units are packed into a single transport unit, it is a fundamental and well-known engineering practice to include length indicators for each sub-unit. This allows the receiver to accurately parse the packed data and reconstruct the original units. A PHOSITA, aiming for the efficient SDU-to-PDU conversion taught by US7075953B2, would predictably employ such length indicators. Using "packing subheaders" (or any in-band length field associated with each packed SDU/fragment) is a common and obvious method to convey this necessary length information.

3. Including at least two fragmentation control bits in a PDU header, indicating absence or presence and orientation of fragments of SDUs:

   • GK acknowledges fragmentation as a known method. When fragmentation is employed, the receiving end requires information about the status of each fragment to correctly reassemble the original data unit. Standard packet fragmentation protocols (e.g., IP fragmentation) use flags and offset fields to indicate if a packet contains a fragment (presence), if it's the first, middle, or last fragment (orientation), and if more fragments are expected. A PHOSITA, integrating fragmentation into the SDU-to-PDU conversion, would find it obvious to include such control bits in the PDU header. "At least two" bits enable signaling multiple states (e.g., no fragment, first fragment, continuing fragment, last fragment), which is a common and predictable design choice for conveying comprehensive fragmentation status.

The "coordination" of packing and fragmentation, emphasized in US8311040B2, is the natural and obvious outcome of applying these known techniques simultaneously to achieve the stated goal of maximizing link efficiency for variable-length SDUs. A PHOSITA, facing the known challenges of bandwidth limitations and diverse SDU formats, would be motivated to leverage both packing and fragmentation, and implement the necessary signaling (length indicators and fragmentation control bits) through conventional means.