Prerequisites & Notation
Before You Begin
Integrated sensing and communications (ISAC) is a 6G cornerstone: one waveform, one hardware, two services. Adding RIS to ISAC expands both the sensing and the communication footprint. This chapter assumes fluency with the joint optimization framework (Ch. 5-7) and basic radar concepts (matched filter, CFAR). It develops the ISAC-specific optimization with a RIS in the loop and culminates in the CommIT RIS-ISAC beamforming framework.
- Joint active-passive beamforming (Ch. 5-7)(Review ch05)
Self-check: Recall the AO framework and its outer-inner structure for MU-RIS.
- Radar fundamentals: matched filter, CFAR, ambiguity function(Review ch29)
Self-check: Derive the matched-filter output SNR for a target with radar cross-section (RCS).
- ISAC waveform design(Review ch29)
Self-check: State the key tradeoff between radar-ambiguity-function sidelobes and communication-spectral-efficiency.
- Cramér-Rao bound (CRB) for parameter estimation(Review ch11)
Self-check: For Gaussian observation , what is the CRB on ?
- Semidefinite relaxation and manifold optimization(Review ch06)
Self-check: Recall the SDR lift for unit-modulus QCQP.
Notation for This Chapter
ISAC-specific notation on top of the single-RIS conventions. Sensing-side metrics (beampattern, CRB) coexist with communication-side metrics (SINR, rate).
| Symbol | Meaning | Introduced |
|---|---|---|
| Radar target position (Cartesian coords) | s01 | |
| Radar cross-section (RCS) of the target | s02 | |
| Received sensing power (radar return) | s02 | |
| Sensing SNR: | s02 | |
| Per-user communication SINR | s02 | |
| Desired radar beampattern (power as function of angle) | s03 | |
| Communication QoS threshold (minimum SINR) | s03 | |
| Sensing beampattern MSE threshold | s03 | |
| Steering vector at radar angle | s02 |